Organic Chemistry II
Laboratory Manual
By
Stephen Anderson
and
Robert Shine
Edited by
Sarah Carberry and Jay Carreon
Ramapo College of New Jersey
Mahwah, New Jersey
January 2010
© 2010 Anderson, Shine, Carberry, and Carreon
Organic Chemistry II
Laboratory Manual
Dr. Stephen Anderson
Dr. Robert Shine
Ramapo College of New Jersey
Contents and Schedule:
Lab 1
Check In, Safety and Procedures
Lab 2
Acid-Catalyzed Dehydration of Cyclohexanol
Lab 3
Williamson Ether Synthesis
Lab 4
Sodium Borohydride Reduction
Lab 5
Hypochlorite Oxidation  Green Chemistry
Lab 6
Grignard Reaction
Lab 7
Diels-Alder Reaction
Lab 8
Nitration of Methyl Benzoate
Lab 9
Friedel-Crafts Alkylation
Lab 10
Qualitative Organic Analysis and Sim-Org
Lab 11
Aldol Condensation Reactions
Lab 12
Hydrolysis of Methyl Benzoate Green Metrics
Lab 13
Analysis of Carbohydrates
Lab 14
Review – Checkout and Laboratory Final Examination
© 2010 Anderson, Shine, Carberry, and Carreon
2
Organic Chemistry II
Laboratory Manual
Appendices
Appendix List:
Appendix A: Qualitative Organic Analysis and Sim-Org
Appendix B: Safety Issues
Appendix C: Comments About Writing Style
Appendix D: Measurements and Significant Figures
Appendix E: Percent Yield Calculation Method
Appendix F: Green Metrics
Appendix G: Chemical Data
Acknowledgements: The Authors wish to thank the following people for their assistance with
this manual: Carol Ichinco (Laboratory Coordinator), Thomas Drwiega (Laboratory Technician),
Gurpreet Kaur (Honors Research Student), Benjamin Barrios (Research Student), and all the
other Instructors who have taught Organic Chemistry Laboratory sections for the past few years.
Dr. Scott Frees and Jeffrey Ludwig are acknowledged for their work in writing and developing
the Sim-Org qualitative organic analysis simulation program.
© 2010 Anderson, Shine, Carberry, and Carreon
3
LAB 1: LABORATORY PROCEDURES
ORGANIC CHEMISTRY LABORATORY PROCEDURES
SCOPE OF THE COURSE
This course offers a comprehensive introduction to laboratory techniques in organic
chemistry for science majors. Chemistry is a mature science that continues to expand and evolve
in step with recent developments in science and technology. Students will perform experiments
that put into practice the ideas discussed in lecture.
E-MAIL AND INTERNET USE
Use will be made of e-mail (Luminis) and the Internet to provide important instructions
to students concerning laboratory material. Students are encouraged to contact the Instructor in
person or by e-mail for additional help, if needed. Information about the course may be
transmitted periodically by the Instructor via a web site for the course. Students should check this
web site at least once a week. Students may not submit lab reports via e-mail or e-mail
attachments or by fax. Lab reports must be submitted as paper copy.
ATTENDANCE
Each lab session will begin at the scheduled time. Attendance at all laboratory sessions is
mandatory and will be recorded. If you are late, it will be noted and recorded. A missed
laboratory experiment cannot be made up at another time and any missed laboratory session will
result in a grade of zero (0) for that experiment unless an alternate library report is completed.
During the course of the semester you will be allowed to substitute one alternate report for any
one lab period you cannot attend. You must discuss the content and deadline of the alternate
report with the Instructor as soon as possible after your absence.
SPECIAL NEEDS
Students with special needs who are registered with the Office of Specialized Services
and require special accommodations should notify the Instructor as soon as possible.
GRADING
Each laboratory session will be graded by a procedure explained to you by your
laboratory instructor. Your in-lab work and your report will be used to determine your grade.
The final laboratory exam will account for about 20% to 30% of your final laboratory course
grade. In grading laboratory sessions, the following will be considered: meeting deadlines,
submitting the necessary forms and reports on time and in good order, being on time for lab, and
working in a safe and efficient manner. Your practical bench skills and laboratory results will
also be analyzed, along with your ability to effectively explain and discuss them in your lab
report.
SAFETY
As with many activities in daily life, working in the organic chemistry laboratory poses
some hazards that you must recognize. Many of the chemicals used can be toxic if not used
correctly. Also, many substances you will use are flammable and must be kept away from
sources of heat that could cause them to ignite and start a fire. Glassware can be broken and
cause cutting hazards. You must always come to the laboratory prepared so that you will be
4
aware of the unique hazards you will confront. You must consult the MSDS forms for the
chemicals you will use so that you will know their toxic and flammability properties. You can
find MSDS data on the Internet by typing the chemical name, a space followed by MSDS in a
Google search box (for example: acetone MSDS). If you have any questions about the
experiment you are performing or the chemicals you are using, please ask the Instructor before
you begin work. When you are done with the experiment, the chemicals you have should be
discarded as hazardous waste or reclaimed material and placed in the proper containers. If you
are pregnant or expect that you may become pregnant, you should consult with a medical doctor
about the potential hazards involved with exposure to organic chemicals. See Appendix B for
more information about safety.
EYE PROTECTION
Students are required to have department approved lab goggles that must be worn at all
times in the laboratory when experimental work is being done. Students who fail to wear eye
protection could be asked to leave the lab by any employee of the College. It is not
recommended that you wear contact lens in the laboratory.
PRE-LABORATORY PREPARATION
It is imperative that students be prepared to perform the scheduled experiments. An
unprepared student is a hazard in a chemistry laboratory. In order to prepare for the experiment,
students are expected to read the appropriate laboratory experiment prior coming to the lab.
Students may be tested at the beginning of the lab period to ensure they are prepared to begin
work. The Instructor also may require students to answer pre-laboratory questions in the lab
notebook.
LABORATORY NOTEBOOK
Students should have a notebook that will be used in the lab for recording all
experimental data. A title should appear at the top of the page for each new experiment. Data
obtained during an experiment should always be neatly and clearly recorded in this notebook.
You should use the department approved notebook for this course. You will be required to turn
in a copy of your experimental data sheet before you leave the lab at the end of the period. You
must include your name, the name of the experiment, and the date of the lab period on the data
page you submit which will graded as part of your report grade. Any measurement data must
have the numerical value recorded to the correct number of significant figures and the units of
that measurement, such as 1.234 g for a weight measurement.
LAB REPORTS
Before leaving the laboratory, each student must submit a laboratory data sheet as
described above. Lab reports can only be submitted for labs that have been attended and must be
submitted at the beginning of the lab session following the lab that is being reported. Points will
be deducted for lateness or for an incomplete lab report. No lab report for a given experiment
will be accepted after graded reports for that lab have been returned to the class. Generally,
graded lab reports will be returned in the next class meeting after the report is submitted. A score
of zero is assigned for a report if the lab report is not submitted.
5
FORMAT OF LAB REPORT
Laboratory reports must be typed on 8.5  11-inch white paper. The report should have a
professional appearance and it must demonstrate that much thought and care went into its
preparation. Some comments about report writing style appear in Appendix C. Spelling and
grammar count. All laboratory reports must be written in the following format that conforms to
the guidelines set forth by the American Chemical Society:
COVER PAGE
Place the following information in the upper right hand corner of the title page or first
page of the report:
Title of the experiment, your name, date of submission
ABSTRACT
The abstract consists of two to five sentences that concisely inform the reader of the
nature of the experiment that was performed and a brief summary of your final results. Note that
the abstract is read immediately after the title and hence need not repeat any information that
already appears in the title. Though the abstract appears at the beginning of the lab report, it
should be the last section of the report that is composed. The abstract should be about 50 to 100
words and should give a concise description of the experiment and the important results that
were obtained. It should not be too general or too specific.
INTRODUCTION
The introduction consists of three to five paragraphs that relate only the most essential
elements of theory to the reader. Consult other sources such as a chemistry textbook for this
information. Include only enough theory so that the reader is made to understand the basic
physical and chemical principles involved in this experiment. If applicable, any pertinent
mathematical and chemical equations must be given in this section. The introduction should
conclude with a one- or two-sentence paragraph that explains the objective or goal of the
experiment.
SAFETY
Students shall describe all relevant safety precautions that were observed during the
course of the experiment. Information about the hazards that may be encountered is particularly
important. Material Safety Data Sheet information should be included. You should give a
summary of the pertinent data (such as: toxicology, flammability, and physical properties) and
not just a copy of the MSDS.
EXPERIMENTAL
For our purposes, the experimental section will consist of a short paragraph that includes
a sentence that refers the reader to some source for the procedure. For example, the student may
write: "The procedure for this experiment appears in the web page for the course (#)." The
number in brackets refers to the citation number. This number is used to refer the reader to the
citation in the References section where the full reference (including information such as the
name of the author, title of book or web site, date of publication, and page number or exact web
address) will appear next to the appropriate number. In addition to the reference citation, any
deviations from the published procedure and any experimental hints or tips that may aid the
6
reader in understanding and repeating the experiment should be included. For example, ‘In this
experiment, the instructor requested that 0.05M HCl be used instead of 0.10M as specified in the
module.’
RESULTS
This section consists of a written paragraph that refers the reader to tables, graphs, data
sheets, and figures that contain your data. It is especially important to inform your reader how
your experimental data were used to calculate your final results. You must explain how you
determined your final results. Include sample calculations with an accompanying explanation.
The use of a spreadsheet program (such as Microsoft Excel) for calculations, tabulation of
results, and graphing is encouraged.
DISCUSSION
This section is used to indicate to the reader how the results relate to the theory and
whether or not the objective was met. In addition, the final results must be compared to literature
values, if available. Reasonable sources of error should be listed and discussed with respect to
their contribution to the final results. The discussion provides a good indication of the student's
comprehension of the material. A good discussion should show that the student was able to
correctly interpret the data and to relate the results to the scientific principles being tested by the
experiment. If the experiment was not successful, then the discussion is equally important in
stating the reasons for the outcome. A good discussion can be written regardless of the success
of the experiment.
CONCLUSION
This section should include a summation of the Results and Discussion sections. It should
only be about 1 paragraph long and is intended to draw together all the pertinent information that
has been determined from the experiment.
REFERENCES
This section consists of a numbered listing of literature or Internet references that were
used to perform the experiment and that were used to write the lab report. This includes a full
reference to the lab module and any other publications or correct web page URLs that you may
have used to obtain literature values and supplemental theory. Note that the reference numbers
must correspond to the reference citations used in the text of the report.
© 2010 Anderson, Shine, Carberry, and Carreon
7
LAB 2: ACID-CATALYZED DEHYDRATION OF CYCLOHEXANOL
PURPOSE:
You will run a synthesis reaction using the techniques of reflux and distillation. An
infrared spectrum of the product will be obtained to assess the success of the reaction.
BACKGROUND INFORMATION:
Organic synthesis is very important in that it allows the experimenter to make new
compounds from compounds that might be more readily available. Sometimes a synthesis
reaction is easy to do and other times great effort and care must be given. This experiment will
require good technique as the cyclohexene product is volatile and can be easily lost by
evaporation thus lowering your yield. The reaction to be done in this laboratory period will be
the acid-catalyzed dehydration of cyclohexanol to give cyclohexene, which is an example of an
E1 reaction.
OH
Cyclohexanol
MW 100.16 g/mol
bp 160-161°C
H3PO4
H2O
Cyclohexene,
MW 82.14 g/mol
bp 83°C
(distilled from the mixture)
Cyclohexanol is a secondary alcohol, which can be protonated by a strong acid. The
protonated alcohol then loses a water molecule to form a secondary carbocation. Loss of a
hydrogen atom on an adjacent carbon atom results in the formation of cyclohexene. It is possible
that a substitution reaction could compete in this synthesis. To minimize this, a strong acid is
used so that the accompanying anion is a weak nucleophile. The acids of choice for this
dehydration reaction are concentrated sulfuric acid and concentrated phosphoric acid. We will
use concentrated phosphoric acid in this experiment as it causes less charring of the organic
materials. Recall that this reaction is a reversible one in that water can be added to an alkene in
the presence of an acid to give an alcohol. Hence, we should be mindful of LeChatelier’s
principle in order to move the equilibrium in the direction we want. If you look at the balanced
equation it becomes obvious that water must be avoided to minimize the undesired reverse
reaction. This is why concentrated acids are used. Concentrated phosphoric acid is 85% pure
whereas concentrated sulfuric acid can be obtained in 100% purity. So, phosphoric acid may be
slightly less advantageous than sulfuric acid.
Since this reaction is not immediate, the reagents must be heated for a period of time to
allow significant amounts of product to form. Reaction times are shortened as the temperature is
increased. So the higher the temperature we can use, the shorter the reaction time. The limit we
are able to achieve is the boiling point of the solution. In order to allow the reaction to proceed at
its boiling point, we must condense and collect the distillate back into the reaction vessel. This is
called reflux. We will do a modified reflux by using a fractional distillation setup. At the
beginning of the heating process, the distillate will condense and flow back into the reaction
vessel. Over time, the hot vapors will reach the thermometer and side arm of the distilling head
and begin to distill over. The success of this method lies in the fact that cyclohexene has a low
8
boiling point (83°C) compared to cyclohexanol (bp of 160-161°C) and will distill over first. If
the mixture is not overheated, no cyclohexanol will distill.
While this is a good method theoretically, significant cyclohexene is lost (as mechanical
loss) in the fractionating column, which will lower the yield substantially. To correct this
problem, a chaser solvent of toluene (bp of 110°C) will be used near the end of the fractional
distillation to push cyclohexene over into the collection vessel.
This experiment has many facets that demonstrate concerns and compromises that must
be considered in the synthesis of a desired compound.
EXPERIMENTAL PROCEDURE:
Place 10.0 mL of cyclohexanol (density = 0.948 g/mL) in a 50 mL round bottom flask
along with 2.0 mL of 85% phosphoric acid and a few black boil easers. Use care in handling the
phosphoric acid. Carefully swirl the flask to ensure the liquids mix. Place the flask in a 50 mL
heating mantle and arrange a fractional distillation apparatus on the flask. Be sure the receiving
vessel is well immersed in an ice bath. Also try not to have much of the receiving vessel opening
exposed to air as the cyclohexene product is very volatile and could be easily lost. If you smell
cyclohexene, which has a characteristic odor, you are losing product and your percent yield will
be lower.
Heat the mixture and note the temperature as the distillation proceeds. You may need to
wrap the fractionating column in aluminum foil so that the hot vapors do not become too cool to
distill over. Also, be sure that you do not pass water through the fractionating column as this will
certainly destroy the fractional distillation. The water should only circulate through the distilling
condenser near the receiving vessel.
Cyclohexanol has a boiling point of 160-161°C and cyclohexene has a boiling point of
83°C. After the cyclohexene that has formed is distilled, you should observe the temperature rise
to distill the unreacted cyclohexanol (which is not desired) or the temperature may drop if no
liquid is distilling over. You should observe that there are a few mL of liquid in the distilling
vessel (unreacted cyclohexanol and phosphoric acid). Turn off the heat and, when possible,
remove the thermometer and its adapter and carefully add 10 mL of toluene, which boils at
110°C (as a chaser solvent) to drive over the cyclohexene that is held up in the fractionating
column. Continue distilling until there is very little liquid in the distilling flask or the temperature
has risen to 110°C.
The material that has distilled over must now be purified. During these procedures keep
the product mixture cold and covered as much as possible. Do all work in the hood. Pour the
product mixture into a separatory funnel and use a small amount of toluene to thoroughly remove
all the liquid from the distillation product vessel. About 3 mL of toluene should be sufficient.
Extract the organic layer in the separatory funnel with an equal volume of saturated sodium
chloride solution to remove some of the dissolved water. Drain off and discard the lower layer
keeping the upper organic layer in the separatory funnel. Now place the organic layer in a
suitable container and add some solid anhydrous drying agent such as calcium chloride or
sodium sulfate. This will remove the last traces of dissolved water from the cyclohexene-toluene
solution. After about 5 minutes, quickly filter this mixture using gravity filtration and a glass
wool or cotton plug to catch the solid drying agent. The filtrate should be collected into a suitable
round bottom flask for the final distillation.
9
While the above work-up procedures are being done, the fractionating apparatus should
have been carefully cleaned and dried using acetone. Now do a final fractional distillation
collecting the distillate that boils below 90°C. Weigh your product and be sure to report your
percent yield calculation in your report. The final distillate should be clear. If it is cloudy, the
water was not completely removed. Your Instructor may wish to take an infrared spectrum of
your product.
IMPORTANT INFORMATION ABOUT THE REPORT:
This will be another report that will require a percent yield calculation. Be sure to
carefully show how you calculate the percent yield and use the proper number of significant
figures. Draw a mechanism using the curved arrow formalism for the conversion of cyclohexanol
to cyclohexene in the presence of catalytic phosphoric acid.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
10
LAB 3: WILLIAMSON ETHER SYNTHESIS
PURPOSE:
This experiment is an example of the Williamson ether synthesis which follows the S N2
mechanism. Here, one analgesic will be converted into another analgesic.
IMPORTANT REACTION:
H
N
HO
Me
O
Acetaminophen
MW 151.16 g/mol
mp 168-172°C
H
N
K2CO3
CH3CH2I
2-butanone
Ethyl Iodide
MW 155.97 g/mol
bp 69-73ºC
EtO
Me
O
Phenacetin
MW 179.22 g/mol
mp 133-136°C
BACKGROUND INFORMATION:
There are many over-the-counter non prescription medications to reduce pain (analgesic),
reduce fever (antipyretic) and reduce inflammation. Salicylic acid, obtained from willow tree
bark, was used more than 100 years ago for its medicinal properties. Since it had undesirable side
effects, much early research was done to find a better alternative. The Bayer Company in
Germany found that, by acetylating salicylic acid, a better pain reliever was obtained. This
compound, acetylsalicylic acid, is well known as aspirin.
Over the years, many different kinds of NSAIDs (non-steroidal anti-inflammatory drugs)
were developed. These include aspirin, acetaminophen, ibuprofen and naproxen sodium.
While much research has been done in developing these profitable drugs, much still
needs to be done to fully understand the biochemical cause of pain and how pain can be relieved.
Pain relief and drug dependence is another area of active research.
EXPERIMENTAL PROCEDURE:
Add 1.300 g of acetaminophen, 2.500 g of powdered anhydrous potassium carbonate,
15.00 mL of 2-butanone, and 1.800 g of ethyl iodide carefully to a 50 mL round bottom flask.
Heat the mixture under reflux for 1 hour. After cooling, add 15 mL of diethyl ether to the flask
and transfer the reaction mixture to a separatory funnel. Extract with two 10 mL portions of 5%
NaOH to remove unreacted acetaminophen. Dry the organic layer with anhydrous sodium
sulfate. Separate the drying agent from the solution by decantation or gravity filtration through a
cotton plug. Evaporate the solvent. Weigh the crude product, calculate the percent yield and
obtain its melting point.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will follow the usual format for synthesis experiments.
Show the complete mechanism of the reaction. Be sure the percent yield calculation is carefully
done. Record the melting point range of the final product and compare the experimental value to
the reported melting point of phenacetin. Using these data, discuss the relative success of the
experiment. Draw a mechanism for the conversion of acetaminophen to phenacetin in the
presence of potassium carbonate using the curved arrow formalism.
© 2010 Anderson, Shine, Carberry, and Carreon
LAB 4: SODIUM BOROHYDRIDE REDUCTION
PURPOSE:
You will use a reduction reaction in the synthesis of hydrobenzoin from benzil using
sodium borohydride as the reducing agent and you will characterize the product by melting
point. Your Instructor may substitute benzophenone for hydrobenzoin in this experiment.
Benzophenone (MW 182 g/mol, mp 47°C) would give benzhydrol (MW 184 g/mol, mp 6567°C) as the reduction product.
IMPORTANT REACTIONS:
O
Ph
HO
H
Ph
NaBH4
Ph
OH
H
Ph
O
Benzil
MW 210.23 g/mol
HO
H
Ph
(1R,2S)-(meso)-Hydrobenzoin
MW 214.26 g/mol
mp 137-139°C
O
Ph
Benzophenone
MW 182.22 g/mol
mp 47-51°C
Ph
H
(1R,2R)-Hydrobenzoin
mp 146-149°C
HO
Ph
H
OH
H
Ph
(1S,2S)-Hydrobenzoin
mp 146-149°C
OH
NaBH4
Ph
OH
Ph
Ph
Benzhydrol
MW 184.23 g/mol
mp 65-67°C
BACKGROUND INFORMATION:
Oxidation and reduction reactions are very important in organic chemistry in the
synthesis of desired compounds. There are many oxidizing and reducing agents that can be used
to achieve the desired product. Some of these redox reagents are general in that they can react
with a large number of functional groups. Other redox reagents are very specific and have
limited but specific reactivity and can cleanly do the conversion that is desired. Sodium
borohydride is such a specific reducing reagent. It can be safely used to reduce an aldehyde or
ketone to an alcohol. Hydride type reagents are rather basic and can often be vigorously
decomposed in water or alcohol. Extreme care should be exercised whenever you work with any
type of hydride. However, sodium borohydride is reasonably safe to use. It does not undergo the
decomposition as vigorously as other hydrides. Further, the reaction can be run in alcohol and
yields are very good. The reaction that will be done in this experiment is generally fast and
almost quantitative.
EXPERIMENTAL PROCEDURE:
Dissolve 0.5 g of benzil (or benzophenone) in a 25 mL Erlenmeyer flask using 5 mL of
95% ethanol. Slight heating may be required but cool to room temperature before adding 0.12 g
of sodium borohydride. In about 3 minutes the reaction is complete as noted by the
disappearance of the yellow color of benzyl (if that reactant were used). After about 5 more
minutes, add 5 mL of water and heat the solution to decompose the large excess of sodium
borohydride. While still warm, add approximately 10 mL of water. Let the solution cool to allow
the product to crystallize. Suction filter the product, dry and weigh it and take its melting point.
IMPORTANT INFORMATION ABOUT THE REPORT:
This experiment is another example of a synthesis reaction. You must calculate the
percent yield as you did before. Be sure to use the correct number of moles from the balanced
equation in your calculation to determine the theoretical yield. Be sure to record both the
observed and reported melting point ranges for your product. Draw a mechanism using the
curved arrow formalism for the conversion of the ketone to the corresponding alcohol in the
presence of sodium borohydride in ethanol.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
13
LAB 5: OXIDATION OF BENZALDEHYDE-GREEN CHEMISTRY
PURPOSE:
This experiment will introduce the student to the new area of Green Chemistry. Green
Chemistry tries to use new reagents or less toxic familiar reagents to be more environmental
friendly. In this experiment, dilute hydrogen peroxide and Clorox (which both present some
hazards) will be used in place of the more usual, more toxic dichromate reagents.
IMPORTANT REACTIONS:
O
O
H
[O]
OH
H2O2 or NaClO
Benzoic acid
MW 122.12 g/mol
mp 121-125°C
Benzaldehyde
MW 106.12g/mol
bp 178-179°C
O
OH
bleach
Benzhydrol
MW 184.23 g/mol
bp 65-67°C
Benzophenone
MW 182.22 g/mol
mp 47-51°C
BACKGROUND INFORMATION:
Green chemistry is that new aspect of chemistry in which environmentally friendly
reagents are used in place of more hazardous traditional reagents. A great deal of research is
currently being done in this area and major success stories have been written. Links to green
chemistry web sites can be found on Robert Shine’s web page for this course (see
http://phobos.ramapo.edu/~bshine/).
One difficulty with green chemistry is finding reagents that perform as well as the older
reagents. It is our hope that we will be able to introduce better experiments in this course as
future studies are done.
We can start with a simple reaction such as the oxidation of benzaldehyde to benzoic
acid. Aldehydes are very easy to oxidize so it was thought that simple household oxidants could
be used in place of the traditional hazardous dichromate reagents. Our study is investigating the
use of dilute hydrogen peroxide and Clorox. In the past few years at Ramapo College, there has
been success using these reagents but the yields have been low. Your data in this experiment will
be used to find the optimum conditions for future classes to use.
In place of benzaldehyde, your Instructor may use benzohydrol or acetophenone in this
experiment. The green advantage of using benzohydrol would be that it may have been the
product from the prior experiment (if your Instructor chose that starting material) and we would
be recycling reagents. Acetophenone should be easily oxidized to benzoic acid by hypochlorite
via a haloform reaction.
14
Clorox, a mild oxidant, is a dilute solution of sodium hypochlorite (NaOCl). Clorox
should never be mixed with ammonia solutions or ammoniated cleansers as a reaction that
releases deadly chlorine gas occurs.
The other oxidant that will be tried is dilute hydrogen peroxide. We have found that a 3%
solution that can be purchased in a drug store is too dilute to give a meaningful reaction. When a
10% solution was used, results were better but still not adequate. In addition, if the 10% solution
comes in contact with the skin, it turns it white for a few hours. More concentrated solutions
exist but the hazard level rises as the concentration is increased.
Your careful observations and well written laboratory reports for this experiment will be
very useful in determining if this experiment could be successful in the future.
EXPERIMENTAL PROCEDURE:
The entire synthetic procedure should be carried out in the fume hood. Although these are
household chemicals, you still need to be careful handling them. If you get any on your hands,
you will not feel it immediately, but white patches will soon appear.
PART 1: Oxidation using Household Bleach
A: Oxidation of Benzaldehyde
Place benzaldehyde (2 mL) and glacial acetic acid (1 mL) in a 125 mL Erlenmeyer flask,
add a magnetic stirrer bar and gently heat on a stirrer-hotplate. To the reaction mixture add
household bleach (30 mL) in approx. 5 mL portions over a 2-3 min. period. After addition is
complete, heat the reaction to approximately 80-90°C (with stirring) for 45 minutes. It is very
important that you do not allow the solution to boil. Remove the flask from the stirrer-hotplate,
allow it to cool to room temperature. Then place it in an ice bath. Filter off the product using a
Buchner funnel, wash the product and reaction flask with ice-cold water, and allow the solid to
dry. Measure the mass of benzoic acid produced, calculate the percent yield, and record its
melting point range.
B: Oxidation of Benzhydrol
Place 1.00 g of benzhydrol, 15 mL of household bleach, 15 mL of ethyl acetate and 0.100
g of tetrabutylammonium hydrogen sulfate in a 125 mL beaker. Using a magnetic stirrer bar, stir
the mixture for 30 minutes. Remove the stir bar and the lower aqueous layer (using a Pasteur
pipette). Extract the organic layer with 10 mL of saturated sodium chloride and then 10 mL of
water. Dry the organic layer over anhydrous sodium sulfate. Decant or gravity filter to remove
the solid drying agent and then evaporate the organic solvent. Determine the melting point and
the percent yield of the benzophenone product.
PART 2: Oxidation using Hydrogen Peroxide
Place benzaldehyde (2 mL) and glacial acetic acid (1 mL) in a 125 mL Erlenmeyer flask,
add a magnetic stirrer bar and gently heat on a stirrer-hotplate. To the reaction mixture add 20%
hydrogen peroxide (30 mL) in approx. 5 mL portions over a 2-3 min. period. After addition is
complete, heat the reaction to approximately 80-90°C (with stirring) for 45 minutes. It is very
important that you do not allow the solution to boil. Remove the flask from the stirrer-hotplate,
allow it to cool to room temperature. Then place it in an ice bath. Filter off the product using a
Buchner funnel, wash the product and reaction flask with ice-cold water, and allow the solid to
15
dry. Measure the mass of benzoic acid produced, calculate the percent yield, and record its
melting point range.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will follow the usual format. Discuss the importance of
Green chemistry. Be sure the percent yield calculation for each method is carefully done. Also,
record the melting point range of the final products and compare the melting point data to the
reported melting point of benzoic acid. Using these data, discuss the relative success of each
experiment.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
16
LAB 6: GRIGNARD REACTION
PURPOSE:
This experiment will introduce the student to the synthesis of a sensitive organometallic
intermediate (the Grignard reagent) which is very useful in the synthesis of a large number of
different functional groups.
IMPORTANT REACTIONS:
Part 1:
Br
MgBr
Et2O
Mg
Phenylmagnesium bromide
Bromobenzene
MW 157.01 g/mol
bp 156°C
Part 2:
MgBr
O
H3O+
OH
Benzophenone
MW 182.22 g/mol
mp 47-51°C
Triphenylmethanol
MW 260.33 g/mol
mp 160-163°C
BACKGROUND INFORMATION:
The Grignard reaction was discovered and developed by a French Nobel laureate in the
early 1900’s. It is an example of an organometallic compound which has a carbon magnesium
bond. Grignard reagents have been extremely useful in the synthesis of a large number of classes
of organic functional groups for the past century. Although Grignard reagents are unstable and
decompose in air and moisture, they can be prepared and used immediately with moderate
difficulty in the undergraduate organic chemistry laboratory. Care will need to be exercised and
the equipment must be thoroughly dried before use to insure success. No water may enter the
reaction mixture until the final product has been synthesized.
Group IA metals (Li, Na, and K) form very basic organometallic compounds which are
very hazardous to handle. They can be spontaneously flammable in air and react explosively
with water to release hydrogen gas. In these cases, the C-M bond is very polar and the carbon
group is highly basic, especially in sodium and potassium compounds.
With the Group IIA metal magnesium, the C-Mg bond is not as polar and the compound
is not as difficult to handle. Yet they are reactive enough to be very useful in synthesis. The exact
17
nature of the bonding in Grignard reagents has been extensively studied in the past century and is
beyond the scope of this discussion. For the purposes of this experiment, one can consider the
bonding to be R-MgBr, where R is an alkyl or aryl group.
Organometallic compounds with transition metals (such as, iron, mercury, lead, tin,
cadmium, and many others) have an even more covalent carbon metal bond. Many of these
compounds are stable and often very toxic. Organic mercury compounds are often mentioned as
environmental hazards in the New Jersey area. One reason for the extreme toxicity of some
organometallic compounds is the volatility that the organic group imparts on the molecule which
makes it easier for entry into the body.
Returning to the chemistry of the organomagnesium (Grignard) compounds, they are
generally prepared by the reaction of an alkyl or aryl halide with magnesium metal turnings. The
magnesium turnings are crushed in a mortar and pestle just before use to expose a fresh surface
on the metal. Of the halides used, iodides are best, fluorides are the least reactive and bromides
are usually preferred for their good reactivity and reasonable cost. Grignard reagents are usually
prepared in anhydrous ether as the volatile ether solvent helps keep air away from the reaction.
It cannot be stressed enough that the ether must be very dry and kept that way if the reaction is to
be successful. Small traces of water will destroy the reagent or keep the reaction from starting.
Once formed, the Grignard reagent must be used immediately. One can combine this
reagent with a large number of different functional group compounds to give a wide variety of
possible products. The Grignard reagent can react with:
1.
2.
3.
4.
5.
6.
7.
Any active hydrogen (such as water, alcohols, carboxylic acids, etc.) to produce and
alkane or arene (usually this is not a desirable reaction).
Formaldehyde to form a primary alcohol.
An aldehyde (other than formaldehyde) to form a secondary alcohol.
A ketone to form a tertiary alcohol (which will be done in this experiment).
An ester to form a tertiary alcohol.
Carbon dioxide (as solid dry ice) to form a carboxylic acid.
Many other classes of compounds to form other useful products.
Due to the great reactivity of Grignard reagents, the alkyl or aryl halide starting material
cannot have any reactive function group as part of its molecule. This generally limits the halide
to be alkyl, alkenyl, alkynyl, or aryl. An ether group is also compatible and unreactive with the
Grignard reagent.
In today’s experiment, bromobenzene will react with magnesium turnings to form phenyl
magnesium bromide (the Grignard reagent). This intermediate will then be immediately treated
with benzophenone to prepare triphenylmethanol (a solid tertiary alcohol).
18
EXPERIMENTAL PROCEDURE:
In order to minimize the exposure of the Grignard reagent to water, the equipment and
reagents used in this experiment must be absolutely dry. All glassware (reaction glassware, two
sample vials and a stirring rod) must be pre-dried in an oven at 110°C for at least 30 minutes
prior to use. The anhydrous diethyl ether solvent and the bromobenzene will be stored over
molecular sieves to absorb any moisture they are exposed to and the magnesium metal will be
pre-dried in an oven and crushed in a mortar and pestle to give a fresh magnesium surface. The
above preparation work will be completed by the staff before you arrive at the laboratory.
PART 1: Generation of Grignard Reagent
The procedure for this experiment is still being developed and your Instructor may give
directions that are different from what follows.
Remove the first reaction vessel or test tube from the oven and cap it with a rubber
septum. Add magnesium powder or turnings (50 mg, 2 mmol) to the tube, minimizing the time
that the tube is un-capped. Carefully add anhydrous diethyl ether (0.5 mL) to the tube using a dry
syringe, injecting the needle through the rubber septum. If a glass syringe is not available a dried
disposable glass pipette can be used instead.
Remove a sample vial from the oven and cap it with a rubber septum. To this vial add
bromobenzene (330 mg, 2.1 mmol) and diethyl ether (0.7 mL) via the syringe as you did for the
first tube. After addition of the ether solvent, do not remove the needle from the septum. As soon
as the ether has been added to the vial, swirl the mixture and immediately remove the entire
bromobenzene-ether mixture by carefully sucking it up into the syringe. Once this has been done,
inject approximately one third of the bromobenzene-ether mixture into the first reaction tube
containing the magnesium metal in ether. Mix the contents and add a pressure release needle to
the septum. If the reaction does not appear to start at this point, first remove the syringe (if used)
containing the remaining bromobenzene-ether mixture. Carefully remove the septum and the
pressure release needle and quickly grind the magnesium metal using the oven dried glass stirrer
rod. Replace the septum and pressure release needle as soon as possible to minimize air-water
exposure. Once the reaction starts, the clear solution will become cloudy and the ether may begin
to boil. At this point, reattach the syringe containing the remaining bromobenzene-ether mixture
and add the rest of the solution drop wise at such a rate that the reaction does no get out of
control. Once the entire contents of the syringe has been added, continue to agitate the reaction
vessel until the reaction is complete, which will be visible when very little, if any, magnesium
metal remains. The synthesized phenylmagnesium bromide is not isolated, but will be used in
situ for part 2.
PART 2: Synthesis of Triphenylmethanol
Remove the second oven dried vial and cap it with a rubber septum. Add benzophenone
(0.364 g, 2.0 mmol) and diethyl ether (1.0 mL) in the same manner and using the same
precautions as you did in part 1. Shake the vial to dissolve the benzophenone and remove the
resulting solution by sucking it up into the dry syringe.
Carefully remove the syringe containing the benzophenone-ether solution and inject it
drop wise into the reaction tube containing the phenylmagnesium bromide. A red color should be
19
observed at this point. After all the benzophenone solution has been added, rinse the vial with a
few drops of ether and inject these washings into the reaction tube. The reaction is complete
when the red color disappears.
On completion, cool the reaction tube in ice, and very carefully add 3 M hydrochloric
acid (2 mL) drop wise with stirring. If there is any un-reacted magnesium metal in your reaction
tube be especially careful as acids react with metals to release hydrogen gas. This could lead to
your reaction solution bubbling out of your tube. On addition of the acid, a two-phase system
should result. Add more ether solvent if the white triphenylmethanol product begins to crystallize
out. Carefully remove the lower aqueous layer using a Pasteur pipette. To the remaining ether
layer add an equal volume of saturated aqueous sodium chloride solution, shake the tube, allow
the layers to settle and remove the lower aqueous layer as before. Dry the ether layer over
calcium chloride pellets for 5-10 minutes. Then carefully transfer the ether layer via pipette into
a pre-weighed beaker. Wash the solid drying agent with a small amount of ether and combine the
washings with the solution in the beaker. Remove the ether solvent by carefully blowing a stream
of air over the solution in the beaker. When it appears to be dry, re-weigh the beaker to record
the mass of triphenylmethanol produced. Then add ice-cold petroleum-ether (1 mL) to the white
residue and grind (triturate) the product with a glass rod. Filter the product using a Hirsch funnel
and air dry the solid. Weigh the solid to record the mass of purified triphenylmethanol obtained.
Calculate the percent yield of the final triphenylmethanol product and determine the melting
point.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will follow the usual format. Be sure the percent yield
calculation is carefully done. Also, record the melting point range of the final product and
compare that melting point to the reported melting point of triphenylmethanol. Using these data,
discuss the relative success of the experiment.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
20
LAB 7: DIELS-ALDER REACTION
PURPOSE:
This experiment will introduce the student to an important cycloaddition reaction. The
Diels-Alder reaction is reversible and the student will need to consider methods to increase the
yield, if possible.
IMPORTANT REACTIONS:
[4 + 2]
cycloaddition
Diene
Dienophile
O
O
O
-Phellandrene
MW 136.23 g/mol
bp 175-176°C
Maleic anhydride
MW 98.06 g/mol
mp 51-57°C
Adduct
H
H O
H
O
O
endo-7-isopropyl-4-methylbicyclo[2.2.2]
oct-4-ene-1,2-dioic anhydride
MW 234.29 g/mol
mp 126-127°C
BACKGROUND INFORMATION:
The Diels-Alder reaction is an example of a cycloaddition reaction discovered by two
German chemists (Otto Diels and Kurt Alder) in the 1950’s. This reaction is an example of a
concerted reaction in which bonds are being made as other bonds are being broken. Effective
overlap of all bonding orbitals is essential for the reaction to occur which leads to a specific
stereochemistry in the products. In this reaction, the endo isomer is formed.
The Diels-Alder reaction is an example of a [4+ 2] cycloaddition reaction in which an
alkene adds in a 1,4 addition to a diene. Neither Diels nor Alder fully understood the generality
or significance of cycloaddition reactions. This was left for Roald Hofmann (now at Cornell
University) and R. B. Woodward from Harvard University to discover in the late 1960’s. The
Woodward Hofmann rules for cycloaddition reactions (which are beyond the scope of this
discussion) were perhaps one of the major discoveries in organic synthesis in the 20th century.
In early work with this reaction, results were mixed and yields varied quite a bit. Later it
was found that this reaction is reversible. If one considers LeChatelier’s rule, it might be possible
to shift the equilibrium in the desired direction.
In the experiment that will be done here, alpha-phellandrene will react with maleic
anhydride. The alpha-phellandrene is a natural product derived from cedar wood and has a
characteristic cedar wood odor. It is not 100% pure so the directions call for an added amount to
be used to compensate for the impurity. Maleic anhydride is a white solid. It can hydrolyze with
water to give maleic acid so water should be avoided if possible. With prolonged exposure to
21
moisture, the anhydride group in the product may convert to the diacid which will have different
properties. The final bicyclic product is usually obtained without difficulty.
EXPERIMENTAL PROCEDURE:
This reaction must be done in a fume cupboard. Place maleic anhydride (0.527 g, 5.4
mmoles) and -phellandrene (1 mL, 85 % pure, 5.4 mmoles) into a 25 mL round bottomed flask
and attach a water-cooled condenser. Add anhydrous acetone (3 mL) through the top of the
condenser and swirl the reaction mixture. The reaction is exothermic and a yellow color should
appear at this point. Heat the reaction under reflux for 1 hour using a steam bath or hot water
bath. After this time, carefully remove the condenser, pour the reaction mixture into a 20 mL
beaker and allow the acetone solvent to evaporate to approximately half of its original volume.
Allow the reaction to cool to room temperature, then cool the reaction vessel in an ice bath to
induce crystallization of the Diels-Alder adduct (scratching with a glass rod may be required).
Filter off your product using a Hirsch funnel, washing the flask with a small amount of ice-cold
acetone. Dry and weigh the final product, record the melting point and determine the percent
yield.
If required, (i.e. if the melting point of the product is much lower than expected)
recrystallize the product using the minimum amount of warm methanol (be very careful to not
overheat as methanolysis of the anhydride group could occur).
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will follow the usual format. Discuss the mechanism of the
reaction and the stereochemistry of the product. Be sure the percent yield calculation is carefully
done. Also, record the melting point range of the final product and compare that melting point to
the reported melting point of the product given above. Using these data, discuss the relative
success of the experiment.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
22
LAB 8: NITRATION OF METHYL BENZOATE
PURPOSE:
This experiment will introduce the student to one of the important electrophilic aromatic
substitution reactions. The experiment uses concentrated nitric acid and concentrated sulfuric
acid so the student will need to use great care in handling these reagents.
IMPORTANT REACTIONS:
HNO3
2 H2SO4
O N O
2 HSO4
H3O
Nitronium ion
CO2Me
CO2Me
HNO3
H2SO4
Methyl Benzoate
MW 136.15 g/mol
bp 198-199°C
NO2
Methyl-3-nitrobenzoate
MW 181.15 g/mol
mp 78-80°C
BACKGROUND INFORMATION:
This experiment and the one next week are examples of electrophilic aromatic
substitution reactions. Aromatic systems such as the benzene ring have enhanced resistance
toward reactions due to the stability that resonance gives to the aromatic ring. Addition reactions
are highly unlikely as they would destroy the conjugated aromatic system. Substitutions can
occur and the best reagent to use should have electrophilic properties as the aromatic ring is rich
in electrons. The class of reactions known as electrophilic aromatic substitution reactions is
studied extensively in the lecture part of the course. These two experiments will show how they
can be performed in the laboratory.
There are five reactions that are normally presented when discussing electrophilic
aromatic substitution reactions. They include:
1.
Nitration using concentrated nitric acid and concentrated sulfuric acid to generate the
nitronium ion electrophile (which will be done in this experiment).
2. Halogenation using a halogen and a Lewis acid to generate the halonium ion
electrophile.
3. Sulfonation using sulfur trioxide as the electrophile. This is the only neutral electrophile
in this series of reactions and this reaction is reversible.
4. Friedel-Crafts alkylation using some source of a carbocation as the electrophile. This
reaction will be done next week and will use an alcohol and concentrated sulfuric acid to
generate the carbocation.
5. Friedel-Crafts acylation using an acyl halide and a Lewis acid to generate the acylium
ion electrophile.
In the experiment that will be done today, a substituted aromatic ring is used which will lead to
meta nitration of the ring. The substituent chosen will moderate the reaction to avoid di- and tri23
substitution of the ring which could lead to explosive products. Trinitrobenzene is explosive. It is
best not to heat the reaction too high or too long to avoid further undesired substitution.
Also note that this reaction often shows a delayed start. It is best to be patient. If the
mixture is heated highly or longer than directed, an uncontrolled reaction may ensue. And, if the
reaction is quickly quenched in an ice bath, it may be permanently stopped. If brown fumes start
to form, the reaction may be proceeding too quickly and should be moderated.
Concentrated nitric acid and concentrated sulfuric acid pose a hazard when being
handled. Gloves must be worn and care must be used. If any of the acid mixture gets on the skin,
it must be immediately washed with large amounts of cold water. Immediately wash the affected
area with water if you suspect that acid may be on your skin. Nitric acid destroys proteins and if
some of it (either as liquid or vapors) gets on the skin, the skin cells will die over a few hours to
days leaving an orange patch on the surface. This generally wears off in a few days.
This reaction usually goes well if care is exercised. The final product is a crystalline solid
with a low melting point.
EXPERIMENTAL PROCEDURE:
Carefully combine concentrated sulfuric acid (0.4 mL) and concentrated nitric acid (0.4
mL) in a suitable test tube or vial and place it in an ice bath. To a second test tube or vial, add
methyl benzoate (0.6 g, 4.4 mmoles) and concentrated sulfuric acid (1.2 mL), flick the container
to mix the components of this viscous mixture, and then cool it in an ice bath as well. Using a
glass Pasteur pipette, carefully add the sulfuric-nitric acid mixture drop wise to the methyl
benzoate solution, using a glass stirring rod to mix the reaction. On complete addition of the acid
mixture, remove the reaction from the ice bath, allow it to warm up to room temperature, and let
is stand for 15 minutes. After this time, in order to crystallize the product, pour the mixture into a
small beaker that contains approximately 5g of ice. Filter the resulting solid using a Hirsch
funnel and wash out the reaction tube with ice-cold water. When all the product has been
transferred to the filtration funnel, wash the product with ice-cold methanol (0.5 mL). Record the
mass and melting point of this crude product and calculate the percent yield. Recrystallize the
product using an equal mass of methanol and re-record the mass, melting point and percent yield
of the pure product.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will follow the usual format. Be sure the percent yield
calculation is carefully done. Also, record the melting point range of the final product and
compare that melting point to the reported melting point of methyl 3-nitrobenzoate. Using these
data, discuss the relative success of the experiment and discuss whether there is any evidence
polysubstitution occurred. Draw a mechanism for the conversion of methyl benzoate to methyl 3nitrobenzoate using the curved arrow formalism.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
24
LAB 9: FRIEDEL-CRAFTS ALKYLATION
PURPOSE:
This experiment will introduce the student to a Friedel-Crafts alkylation reaction, another
one of the important electrophilic aromatic substitution reactions. The experiment uses
concentrated sulfuric acid to generate an unstable carbocation.
IMPORTANT REACTION:
OMe
OMe
H2SO4
OH
MeO
1,4-dimethoxybenzoate
MW 138.16 g/mol
bp 54-56°C
MeO
2-methyl-2-propanol
MW 74.12 g/mol
bp 83°C
1,4-di-tert-butyl-2,5-dimethoxybenzene
MW 250.38 g/mol
mp 104-105°C
BACKGROUND INFORMATION:
The Friedel Crafts reaction, named in honor of its two founders, is another example of an
electrophilic aromatic substitution reaction. Two variations exist - an alkylation using a
carbocation and an acylation using an acylium ion. In this experiment, an alkylation will be
performed. Any source of a carbocation can be used in a Friedel Crafts alkylation reaction.
Historically, alkyl halides were treated with the Lewis acid, aluminum trichloride. The current
experiment will use an alcohol in concentrated sulfuric acid. One could also use an alkene with
sulfuric acid.
The Friedel Crafts alkylation reaction has many problems that make the acylation
reaction (followed by a Clemmensen or Wolff-Kishner reduction) a better choice. However, by
carefully choosing the reagents in this experiment the problems were minimized.
The three main difficulties involve the activity of the ring, the possibilities of carbocation
rearrangement, and further activation of the ring by the adding alkyl groups. By choosing tertbutyl alcohol in this experiment, rearrangement of the carbocation is not a factor as the tertiary
carbocation that is generated will not rearrange. The activity of the benzene ring is enhanced by
the addition of two methoxy groups. The bulky tert-butyl groups stop the polyaddition at
disubstitution. You may want to further ponder the choice of reagents in this reaction which
gives a good yield of only one isomer compared to many possible isomers in normal alkylation
reactions.
EXPERIMENTAL PROCEDURE:
Place 1,4-dimethoxybenzene (0.300 g, 2.2 mmoles) and acetic acid (1 mL) in a suitable
test tube or vial (not micro-scale) and, if needed, gently warm to dissolve. Add pre-melted t-butyl
alcohol (0.5 mL) to this tube and cool the entire mixture in an ice bath. Carefully add
concentrated sulfuric acid (1 mL) drop wise via a glass pipette, mixing the solution with a glass
rod after each drop. A solid product may be visible at this point, but in order to complete the
reaction, remove the reaction vessel from the ice-bath, allow it to warm to room temperature, and
25
let it stand for 10 minutes. After this time, re-cool the tube in ice in order to induce complete
crystallization. At this point, very carefully add water (5 mL) drop wise to the mixture in the
reaction vessel, stirring after the addition of each drop. Filter off the product using a Hirsch
funnel and wash the solid with ice-cold water. You could also further wash the crystals in the
Hirsch funnel with cold methanol to purify it. After drying, record the mass and melting point of
the crude product and determine the percentage yield. If needed, recrystallize the product in the
minimum amount of hot methanol, and determine the mass, melting point and percent yield of
the purified product.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will follow the usual format. Discuss the mechanism of
this reaction. Be sure the percent yield calculation is carefully done. Also, record the melting
point range of the final product and compare that melting point to the reported melting point of
1,4-di-tert-butyl-2,5-dimethoxybenzene. Using these data, discuss the relative success of the
experiment.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
26
LAB 10: QUALITATIVE ORGANIC ANALYSIS AND SIM-ORG
PURPOSE:
This experiment will introduce the student to qualitative organic analysis. A number of
test tube reactions will be done to identify an aldehyde and/or a ketone unknown in Part A and a
computer simulation program called Sim-Org will be used as a homework assignment in Part B.
IMPORTANT REACTIONS AND DATA:
Part 1: Tollen’s Test
O
R
O
2 Ag(NH3)2OH
H
O
R
NH4
2 Ag
H2O
3 NH3
Silver
Mirror
Aldehyde
Part 2: Iodoform Test
O
R
O
Me
4 HO
3 I2
O
R
Methylketone
3 I
CHI3
3 H2O
Iodoform
Part 3: 2,4-Dinitrophenylhydrazones
O2N
O
R
R'
N
O2N
R
H
H2N
N
R'
NO2
N
H
NO2
H
2,4-dinitrophenylhydrazone
2,4-dinitrophenylhydrazine
Part 4: Semicarbozones
Cl
R
N
R
R'
H
NH2
O
N
O
H3N
O
N
R'
N
H
NH2
-H2O
Semicarbazide
hydrochloride
N
H
Cl
Semicarbazone
27
LAB 10: Table of Unknown Aldehydes and Ketones
Compound
2-heptanone
3-heptanone
n-heptanal
n-butanal
Acetone
3-pentanone
Benzaldehyde
Acetophenone
Cinnamaldehyde
Hexane-2,5-dione
mp (°C)
of 2,4-DNP
89
81
108
123
126
156
237
238
255
257
mp (°C)
of Semicarbazone
123
101
109
95106
187
138
222
198
215
224
BACKGROUND INFORMATION:
This experiment will be the first of a few experiments that will explore qualitative
organic analysis. Analysis of unknown compounds is routinely done by chemists and occupies
much of the time expended by scientists. Analytical chemistry is an entire separate study which,
by its very nature, crosses into other branches such as organic chemistry. Analytical chemistry
can be qualitative (interested only in the identification of an unknown) or quantitative (interested
in the nature and percentage composition of unknowns). Of the two, qualitative is less
demanding. Qualitative analysis may use instruments or classical wet chemical test tube
reactions. Instrumental analysis was introduced last semester in the discussions on infrared and
proton magnetic resonance spectroscopy. Wet chemical analysis was also presented in the
experiment that studied SN1 and SN2 reactions. This experiment will expand on that brief
introduction last semester.
Wet chemical analysis usually involves using simple and quick test tube reactions that
have clear observations. However, since many factors can affect the result, the observer must
look beyond the observation and carefully interpret the data in making a decision about the
identity of an unknown. Reactions that quickly give a precipitate, color change or gas evolution
are ideally suited for qualitative tests.
Usually, in organic chemistry a qualitative test only identifies the functional group class
to which the unknown belongs. Further work must be done to fully determine the exact identity
of the unknown compound. This later aspect of qualitative organic analysis is called ‘making a
derivative’.
In today’s experiment there are four tests. The first two (Tollen’s test and iodoform
reaction) are used to get a general class of possibilities. The last two (2,4dinitrophenylhydrazone
formation and semicarbazone formation) are used to make derivatives. Actually, in the broader
scheme of qualitative organic analysis, the 2,4-dinitrophenylhydrazone reaction identifies the
class and makes a derivative. However, since we know that today’s unknowns are aldehydes or
ketones, this test does not supply any useful differentiation as it is positive for both these classes.
The Tollens test gives a precipitate of silver metal (either as a beautiful silver mirror on
the inside of the test tube or a black precipitate of colloidal silver) if the unknown is an aldehyde.
This mild oxidizing agent can also give a positive test for any very easily oxidized organic
28
compound such as some carbohydrates. Further note that an insoluble unknown aldehyde may
give a false negative test if the reagents are not mixed thoroughly.
The iodoform test gives a light yellow precipitate of iodoform if the unknown has a
methyl carbonyl group as part of the molecule. Since the reagent is also mildly oxidizing, a
methyl group next to a secondary alcohol group will give a positive test. The test is positive for
2-pentanone, acetone, 2-butanone, ethanol, 2-propanol and like compounds. The test is negative
for 3-pentanone, for example. The iodoform that forms has a melting point of 117°C but cannot
be used as a derivative as it is the same product no matter what the unknown is.
The formation of a 2,4-dinitrophenylhydrazone is a messy reaction. Sulfuric acid is one
of the ingredients in the test reagent. The precipitate is difficult to filter and dry. Some success in
cleaning the product can be achieved by washing the solid with cold ethanol. Since percent
yields of derivatives are never an issue, loss of material is acceptable if a purer solid results.
Sometimes, the color of the 2,4dinitrophenylhydrazone (2,4-DNP for short) can give some
information about the unknown. Highly conjugated carbonyl groups give deep red 2,4-DNP
derivatives while non conjugated carbonyl groups give yellow 2,4-DNP compounds.
The formation of a semicarbazone derivative is a nice second choice in identifying an
unknown. Since precipitation can be difficult it is usually not a first choice.
Considering the table of data above, if the unknown were 3-pentanone and a successful
2,4-DNP was prepared with a melting point of, say, 153°C, there would be no need to make a
second derivative as this melting point would uniquely identify the unknown from this list of
possibilities. However, if the unknown were acetone, the 2,4-DNP would not clearly rule out nbutanal as their 2,4-DNP derivatives have similar melting points. A semicarbazone would clearly
identify what the unknown would be in this case. However, other data would help distinguish
acetone from n-butanal. A Tollen’s test would be positive for n-butanal and the iodoform test
would be positive for acetone. So, the final identification of an unknown is achieved by an
analysis of the data available rather than following a rigid set of rules or procedures.
EXPERIMENTAL PROCEDURE:
Your goal is to identify the unknown aldehyde or ketone sample assigned to you from the
table. The tests in parts 1 & 2 will enable you to narrow your search to a particular type of
compound, and measuring the melting points of the derivatives you synthesize in parts 3 & 4 will
give the identity of a particular aldehyde or ketone.
PART 1: Tollen’s Test
This test must be performed on three samples: a known aldehyde (positive test), a known
ketone (negative test) and your unknown sample.
Clean three test tubes by adding sodium hydroxide solution (2 mL) to them and heating
them in a water bath.
To prepare the Tollens reagent, place a 0.03 M solution of silver nitrate solution (2 mL)
into a 10 mL volumetric flask and add a 3 M of sodium hydroxide solution (1 mL) to produce a
grayish suspension of silver oxide. To this, add a 2.8 % solution of ammonia (0.5 mL) dropwise
with shaking. If the precipitate does not dissolve, add more ammonia dropwise until it does to a
maximum of 3 mL. Then dilute the entire mixture to 10 mL total by addition of water. The
Tollens reagent can form explosive compounds on standing and should not be stored.
Remove the sodium hydroxide solution from your three test tubes, rinse them with water,
and add your freshly prepared Tollens reagent (1 mL) to each of the tubes. To the first tube add
29
one drop of your known aldehyde, to the second tube add one drop of your known ketone and to
the third tube add one drop of your unknown. Allow the tubes to stand for several minutes and
look for the appearance of a silver mirror coating on the inside of the tube. If no precipitate has
formed, heat the test tube in a warm water bath for a few minutes.
PART 2: Iodoform Test
This test must be performed on three samples: a known methyl ketone (positive test), a
non-methyl ketone (negative test) and your unknown sample.
Place the sample to be tested (approximately 50 mg or three drops) in a test tube and
dissolve it in water (2 mL). (If it does not dissolve in water, repeat the procedure and dissolve it
in 2 mL of 1,2-dimethoxyethane instead). Add 3 M sodium hydroxide solution (2 mL) followed
by the careful addition of the iodoform solution (3 mL). For a positive test with a known methyl
ketone, the iodoform reagent’s color should disappear and the yellow iodoform product
separates. Repeat the procedure for a known non-methyl ketone and your unknown.
PART 3: 2,4-Dinitrophenylhydrazone
Place the 2,4-Dinitrophenylhydrazine solution (5 mL) in a test tube and add
approximately 50 mg (or three drops) of your unknown sample. Heat the sample tube in a water
bath for several minutes until the presence of a precipitate is observed. Then cool the reaction
tube in an ice bath and filter off the product using a Hirsch (or perhaps a Buchner funnel would
be better) funnel. Wash the product and the test tube with ice-cold water, and then wash the
product with ice-cold ethanol and allow the solid to dry thoroughly. Record the melting point
range of your product.
PART 4: Semicarbazone
Place the semicarbazide hydrochloride solution (0.5 mL) in a test tube and add
approximately 100 mg of your unknown sample. To this add methanol (1 mL) and pyridine (10
drops, use in a fume hood), then heat the sample tube in a water bath for 10 minutes. Cool the
reaction tube in an ice bath and allow the product to crystallize (you may need to scratch the tube
with a glass rod to induce crystallization). Filter off the product using a Hirsch funnel and wash
the product and the reaction tube with ice-cold water. Finally, wash the product with ice-cold
methanol and allow it to dry thoroughly. Record the melting point range of your product.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will be different from the usual format of the past few
experiments. No percent yield calculation will be done. Melting point ranges of any derivatives
must be recorded and compared to the melting points given in the table to determine the identity
of any unknown. The identity of any unknown and its unknown number should be given along
with conclusive evidence that supports the claim that is made.
END OF LABORATORY EXPERIMENT PART A (SEE PART B ON NEXT PAGE)
© 2010 Anderson, Shine, Carberry, and Carreon
30
LAB 10: PART B: SIM-ORG SOFTWARE HOMEWORK ASSIGNMENT
PURPOSE:
The student will use a computer simulation program called Sim-Org developed at
Ramapo College to learn a great deal about qualitative organic chemistry. After some practice
with the software, the student will be asked to do a number of unknown analyses. This
assignment will be done on your own time in the next few weeks. The program may be run on
any computer on campus. It is not available on the internet. Exact instructions about this
assignment and how to run the program will be given to you. Also, see Appendix A at this time
to see a longer, more informative version of the Program Help section which appears below.
BACKGROUND INFORMATION:
QUALITATIVE ORGANIC ANALYSIS
SIM-ORG PROGRAM HELP SECTION
SHORT VERSION
SEE APPENDIX A FOR LONG VERSION
Dr. Scott Frees and Dr. Robert Shine and Jeffrey Ludwig
Ramapo College of New Jersey
Mahwah, NJ 07430
CONTENTS:
Introduction
Solubility Classification
Functional Group Classification Tests
Derivative Formation and Use
Final Identification of an Unknown Substance
INTRODUCTION
There are two methods for identifying the structure of an unknown organic compound.
The first and older method is to run classification tests to identify the functional group of the
compound followed by the production of one or more derivative compounds to confirm the exact
nature of the unknown. The second method is to determine the spectral properties of the
unknown using mainly infrared and proton magnetic resonance spectroscopy. The first method
will be covered in this simulation program. This program has 12 different functional group
classes and 500 different unknowns. There are 22 different classification tests to determine the
functional group of the unknown. There are 21 different derivatives to help identify the exact
name for the unknown. Since this program is still under development as this manual is being
printed, special instructions for the use of Sim-Org will be given as a handout when the
assignment is presented.
The general method to determine the identity of an unknown substance by classical
methods is to gather some introductory information about the compound. Note the odor, color,
and melting or boiling point of the material. Then find its solubility characteristics by doing a
31
solubility classification as described below. From the information obtained from the solubility
classification run appropriate functional group classification tests to identify the group to which
the unknown belongs. Then the unknown is converted into one or more different solids called
derivatives. Consulting tables of derivative melting points one can then identify the exact identity
of the unknown compound.
In order to intelligently conduct the functional group classification tests a solubility
classification is usually done first to narrow down the possible functional group possibilities.
A problem may arise when an unknown substance has two or more functional groups in
the molecule. This may lead to confusion when interpreting the functional group and could lead
one to the wrong table of derivatives. Such unknowns are more difficult to identify. There are a
few such compounds in this simulation program.
SOLUBILITY CLASSIFICATION
The solubility of an organic compound in various solvents can give valuable information
about the unknown. The general rule of 'like dissolves like' or 'polar compounds dissolve more
readily in polar solvents' is useful. Also, organic acids (such as carboxylic acids and phenols)
react with bases to form water soluble salts and organic bases (such as amines) react with acids
to form water soluble salts. It should be noted that the polarity of an organic compound is
increased by the kind and number of polar functional groups in the molecule and that the polarity
decreases as the size of the non polar aliphatic group in the molecule increases.
With this background, one begins the solubility classification by adding 3 drops or 3 mg
of the unknown to 3 mL of water and shaking the mixture. If the unknown dissolves, it is a polar
compound and is placed in solubility group S1. An unknown in class S1 is then tested as above
using ether as the solvent. If it dissolved in both water and ether it is then placed in class S2. For
unknowns that do not fall into either class S1 or S2, the unknown’s solubility in 5% sodium
bicarbonate is determined. If it is soluble, the unknown is placed in class A1. If it is not soluble,
the solubility in 5% sodium hydroxide is studied. If it is soluble at this point, the unknown
belongs in class A2. If an unknown is insoluble to this point it is next tested for solubility in 5%
hydrochloric acid. Compounds soluble in 5% hydrochloric acid are placed in solubility class B1.
For compounds insoluble to this point the next solvent to try is concentrated sulfuric acid.
Unknowns soluble in only this acid are placed in solubility class N1. A further distinction can be
made for compounds soluble in concentrated sulfuric acid by testing their solubility in 85%
phosphoric acid. Such compounds that are soluble in 85% phosphoric acid are placed in class
N2. Finally, for compounds insoluble to this point are paced in class IN.
These solubility classes and their consequences can be summarized below:
S1
These are very polar compounds which consist of salts of carboxylic acids or amines. It is
also possible the compound is of low molecular weight and has many polar functional groups
such as a carbohydrate.
S2
These compounds are low molecular weight (generally less than 5 carbons) with a polar
functional group such as carboxylic acid, amine, alcohol, aldehyde, or ketone.
A1
Higher molecular weight carboxylic acids fall into this class.
A2
Phenols show this kind of solubility.
B1
Primary, secondary and tertiary amines fall into this class. However, if there are two or
more phenyl groups on the nitrogen, the amine will probably not be basic enough to form the salt
and will, then, be insoluble.
32
N1
These are higher molecular weight compounds (generally more than 9 carbons)
containing an oxygen atom.
N2
These are medium size molecules (generally containing from 5 to 9 carbons) containing
an oxygen atom.
IN
These are neutral compounds. Alkyl halides and alkanes fall into this class.
The results of a solubility classification should not be strictly interpreted as there are
many overlaps. Use the results of this classification only as a focus into which classification tests
should be done first.
FUNCTIONAL GROUP CLASSIFICATION TESTS
Below are listed 22 chemical tests that could be used to help identify an unknown. The
tests are listed in numerical/alphabetical order.
1. 2,4-dinitrophenylhydrazone
2. Acetyl chloride
3. Basic hydrolysis
4. Beilstein
5. Benedict
6. Bromine in carbon tetrachloride
7. Ceric nitrate
8. Chromic acid
9. Combustion
10. Ferric chloride
11. Ferric hydroxamate
12. Ferrous hydroxide
13. Hinsberg
14. Hydroxylamine hydrochloride
15. Iodoform
16. Lucas
17. Nitrous acid
18. pH in ethanol/water
19. Potassium permanganate
20. Silver nitrate in ethanol
21. Sodium fusion
22. Tollens
DERIVATIVE FORMATION AND USE
Below are listed 21 derivatives that could be prepared from various unknowns to help in
a final determination of the unknown. The derivatives are listed in numerical/alphabetical order.
1. alpha-naphthylurethane
2. 2,4-dinitrophenylhydrazone
3. 3,5-dinitrobenzoate
4. Acetamide
5. Acid from hydrolysis
6. Amide
7. Anilide
33
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Benzamide
Benzenesulfonyl chloride
Bromo derivative
Methiodide
Neutralization equivalent
Oxime
Phenylhydrazone
Phenylurethan
Picrate
p-Nitrobenzyl ester
p-Nitrophenylhydrazone
p-Toluenesulfonamide
p-Toluidide
Semicarbazone
FINAL IDENTIFICATION OF AN UNKNOWN SUBSTANCE
Tables of organic substances can be used to identify the unknown based on the results of
the classification tests and the derivative melting point results that you obtained.
TABLES OF UNKNOWNS - Once the derivative melting point data have been recorded enter
the Tables of Unknowns by selecting the suspected functional group class. Here a list of organic
compounds separated by type will appear. Select the family that the unknown belongs to. A list
of all the compounds of that type, presented in order of increasing boiling/melting point will
appear. Also listed are the melting points of any derivatives that can be synthesized from the
class of the unknown compound. By matching the table data with the unknown compound data
obtained above, one can identify the unknown.
ANSWER TRIAL - Based on all the melting point data in the Tables of Unknowns, one will now
have an idea of what the unknown sample is. To see if you are correct, you can enter it into the
program by selecting Answer Trial. Make sure that you select the compound correctly, exactly as
it appears in the table of unknowns. If you are correct, a congratulation message will appear. If
you are wrong, first re-check your data for the unknown. If it is still incorrect, then you will need
to go back into the program in order to correctly identify the unknown sample.
IMPORTANT INFORMATION ABOUT THE REPORT FOR THIS ASSIGNMENT:
You will be assigned a number of unknowns to determine using the Sim-Org software. For your
report, be sure to identify the unknown number and compound name for each unknown. After
you give the name of the unknown, be sure to carefully and completely describe how you
reached your decision. Tell the tests you did to determine the identity of the compound and how
you eliminated other possibilities.
END OF SIM-ORG ASSIGNMENT
© 2010 Scott Frees and Robert Shine
34
LAB 11: PART A: ALDOL CONDENSATION REACTION
PURPOSE:
These experiments will introduce the student to one of the many condensation reactions
in Organic Chemistry. These two syntheses (Part A and Part B) usually give good yields with
little difficulty. Both can be completed within one lab period.
IMPORTANT REACTION:
O
O
O
2
NaOH
H
Benzaldehyde
MW 106.12 g/mol
bp 178-179°C
Me
Me
Acetone
MW 58.08 g/mol
bp 56°C
Dibenzalacetone
MW 234.29 g/mol
mp 110.5-112°C
BACKGROUND INFORMATION:
The aldol addition reaction is one in which two aldehyde molecules react with one
another to give a product which contains both an aldehyde and alcohol function group, hence the
name ‘aldol’. A molecule of water can easily be lost from this product giving a conjugated alphabeta unsaturated aldehyde. If this dehydration occurs, the reaction is called a condensation
reaction. The overall reaction in that case would be called an aldol condensation. There are very
many variations of reactions that seem to have an aldol flavor and such reactions are often called
aldol reactions even though they are technically different. The reaction in this experiment is
really a Claisen-Schmidt reaction because it is a reaction of an aldehyde with a ketone. Aldol
type reactions will be thoroughly presented in the lecture part of this course.
This broad class of reactions has a common mechanism. One of the molecules has a
mildly acidic hydrogen which can be removed by a strong base to give a carbanion. The resulting
carbanion acts like a nucleophile and attacks a partially positively charged carbon in a second
molecule. The negative charge on this addition product is removed in some way depending on
the nature of the starting molecules. One way would be to add a proton. Another would be to
eliminate an anion.
Aldol and related reactions are extremely important in organic synthesis as they allow the
chemist to construct larger molecules from smaller ones. In these reactions, a carbon-carbon
bond is formed. Also of great importance is that the product molecule can have many different
useful functional groups which can be transformed in subsequent reactions to other useful
products.
The strength of the base that is used is determined by the acidity of the active hydrogen
compound. Often the base of choice is sodium hydroxide or sodium ethoxide which are effective
in removing a hydrogen that has a pKa in the 1720 range. The alpha hydrogen to a carbonyl or
ester group often has such a pKa due, in part, to the resonance stabilization of the resulting anion.
In the first experiment to be done today, the alpha hydrogen on an acetone molecule is
removed by the hydroxide ion giving a carbanion which attacks the carbonyl of a benzaldehyde
molecule. A hydrogen ion then adds to neutralize the adduct. A water molecule is lost from this
adduct to extend the conjugated system. Remember that conjugated systems increase the stability
of a compound. An alpha hydrogen on the other methyl group of the acetone molecule repeats
35
the process described above with a second benzaldehyde molecule giving the final product,
dibenzalacetone. Two molecules of water are formed as products in this reaction. The final
product is a nicely crystalline yellow solid.
EXPERIMENTAL PROCEDURE:
Place sodium hydroxide (2.5 g) in a 100 mL Erlenmeyer flask and add water (25 mL) and
ethanol (20 mL). Add a magnetic stirrer bar and stir until all the NaOH has dissolved. To a
second reaction vessel, add benzaldehyde (2.65 g, 0.025 mol) and acetone (0.725 g, 0.0125 mol).
Add approximately half of the aldehyde-ketone solution to the sodium hydroxide solution, and
stir for 10 minutes with a watch glass covering the top of the flask. After this time, add the
remainder and stir for a further 10 minutes. Filter off the product using a Buchner funnel and
wash the product with water until the washings no longer appear to be basic (test using pH
paper). The best way to do this is to remove the vacuum tube from the filter flask, fill the
Buchner funnel with water, carefully stir the product with a glass rod and re-apply the vacuum.
Each time the funnel is filled with water, add some litmus paper to the solution to test the pH.
When all traces of NaOH have been removed via water washing, dry the product and record the
mass and melting point of the crude product. Then calculate the percent yield. Recrystallize the
product from the minimum amount of hot ethanol, recording the mass, melting point and percent
yield of the pure product.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will follow the usual format for synthesis experiments. Be
sure the percent yield calculation is carefully done. Be sure to pay attention to the coefficients in
the balanced equation when determining which starting material is the limiting reagent. Record
the melting point range of the final product and compare that melting point to the reported
melting point of dibenzalacetone. Using these data, discuss the relative success of the
experiment.
END OF PART A EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
36
LAB 11: PART B: A SOLVENT-FREE ALDOL REACTION
PURPOSE:
This experiment is yet another example of a condensation reaction. Avoiding the use of a
solvent is one of the techniques used by the Green Chemistry method.
IMPORTANT REACTION:
O
O
Me
O
NaOH
H
Me
Acetophenone
MW 120.15 g/mol
bp 202°C
4-Methylbenzaldehyde
MW 120.15 g/mol
bp 204-205°C
Me
4-Methylbenzylideneacetophenone
MW 222.3 g/mol
mp 93-94.5°C
BACKGROUND INFORMATION:
This experiment is a condensation reaction similar to the one done above. The synthesis
of the unsaturated ketone will be achieved by the reaction of a ketone with an aldehyde using
sodium hydroxide as the base. The difference will be that no solvent will be used in this reaction.
The reduction in the amount of hazardous waste that is generated in a given process is one of the
methods used in Green Chemistry. Elimination of the solvent should reduce the quantity of
hazardous waste.
Usually, solvents are needed to give mobility to the reagents so that the reacting
molecules can collide and then react with one another. Reactions between solid materials go
slowly if at all. Normally the solvent used in a reaction must be removed when the desired
product is being purified. This generally results in the generation of more hazardous waste than
is necessary.
The choice of reagents in this reaction provides some mobility on their own. The two
reacting molecules are both liquids. However, the necessary base, sodium hydroxide, is a solid
and must touch the acetophenone molecule to remove the alpha hydrogen on the methyl group.
This will be achieved by grinding all three reagents together in a mortar and pestle. The
generation of an equimolar amount of water as a product of the reaction will give some added
mobility to the reactants. The product is a solid material which makes its isolation from the
reaction mixture easier.
One thing to note in the work up procedure of this experiment is that water is added to the
solid product until the solution does not have a basic pH. Be sure to record the approximate
amount of water you will need to reach a neutral pH. If much water is used the Green Chemistry
aspect will be lessened. In your report, comment on how successful this reaction is from a Green
Chemistry perspective. How much waste was generated and how hazardous was that waste?
What could be done to treat the waste to reduce its volume or make it less hazardous?
EXPERIMENTAL PROCEDURE:
Place para-methylbenzaldehyde (0.5 g, 4.2 mmol), acetophenone (0.5 g, 4.2 mmol) and
sodium hydroxide (0.18 g, 4.5 mmol) into a mortar and grind the components together for 5
37
minutes. After this time, add a small amount of water to the mortar to aid in the transfer of the
yellow product to a Hirsch funnel. Wash the product with as little water as possible until the
washings no longer appear to be basic. The best way to do this is to remove the vacuum tube
from the filter flask, fill the Hirsch funnel with water, carefully stir the product with a glass rod
and re-apply the vacuum. Each time the funnel is filled with water, dip the end of a piece of
litmus paper to the solution to test the pH. When all traces of NaOH have been removed via
water washing, dry the product and record the mass and melting point of the product. Then
calculate the percent yield.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will simply be a separate results and discussion section.
Discuss each reaction along with the mechanism and be sure to point out the important
differences between the two reactions. Be sure the percent yield calculation is carefully done.
Record the melting point range of the final product and compare that melting point to the
reported melting point of 4-methylbenzylideneacetophenone. Using these data, discuss the
relative success of the experiment in your discussion section.
END OF PART B EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
38
LAB 12: HYDROLYSIS OF METHYL BENZOATE-GREEN METRICS
PURPOSE:
This experiment will use microwave energy to cause a hydrolysis of the ester methyl
benzoate to benzoic acid using a 5% aqueous sodium hydroxide solution. After the reaction
mixture cools, the solution will need to be acidified to cause the precipitation of benzoic acid.
This experiment will also introduce the concept of Green Metrics. Please read Appendix F
(Green Metrics).
IMPORTANT REACTIONS:
O
O
OMe
1. 5% NaOH
OH
2. conc. HCl
Methyl Benzoate
MW 136.16 g/mol
bp 198-199°C
Benzoic Acid
MW 122.12 g/mol
mp 121-123°C
BACKGROUND INFORMATION:
The hydrolysis of an ester is an easy and important reaction in organic chemistry. One
can use an acid or a base to shorten the time needed for the reaction to occur.
The acid catalyzed hydrolysis of an ester gives the product in the free acid form without
further pH adjustment. While this may seem preferable, it is seldom done as this reaction is
reversible and the equilibrium process significantly lowers the yield.
The base promoted reaction forms the sodium salt of the carboxylic acid which cannot
enter into an equilibrium reaction so the reaction can proceed to completion giving a high yield
of product. Note that the base, sodium hydroxide, is not a catalyst in this reaction as it is
consumed in forming the sodium salt. The free acid form is recovered from the sodium salt quite
easily by a simple pH adjustment. In this reaction, concentrated hydrochloric acid will be used to
acidify the basic reaction product. Since benzoic acid is moderately water soluble, it is necessary
to limit the amount of water in the solution.
Microwave heating will be used in this experiment. As mentioned in an earlier
experiment, the use of microwave energy for heating dates back to the 1960’s and became
widespread in the 1980’s. Since microwave energy can penetrate deep within a molecule, the
entire molecule can be heated at the same time. Conventional heating is generally done by
conduction and heats from the outside to the inside of the sample. Therefore, microwave heating
can be faster than conventional heating. However, for heating to occur, the microwave energy
needs to be absorbed by the bonds in the molecule. Absorption of energy is better in polar bonds
and poor in nonpolar bonds. Hence, water heats rapidly in a microwave oven. It is said that
alkanes do not heat well with microwave energy.
The design of a microwave oven presents some challenges to the designer. It is hard to
have a uniform distribution of microwave energy in the cabinet. Further, if no absorption of
microwave energy occurs a reflection of energy in the unit can destroy to apparatus. Some
manufacturers warn that operating a microwave oven when empty can ruin the oven.
39
Microwave ovens can also cause fires. Many people who have made popcorn in a
microwave oven have seen burnt popcorn kernels at one time or another. It is important to
remember that three things are needed for a fire to start: a source of ignition such as microwave
energy, a combustible substance such as many organic compounds, and a source of oxygen such
as air. It is important that one follows the experimental details carefully to work in a safe
manner.
Microwave energy can penetrate the human body and can interfere with certain electronic
devices that may be implanted for health reasons (such a cardiac pacemakers). If you have
implanted electronic devices, let the Instructor know and avoid the lab while the microwave unit
is turned on.
Please make careful observations during this experiment and comment on any success or
failure in your report.
EXPERIMENTAL PROCEDURE:
You will use the laboratory microwave in this experiment. Be especially careful when
handling the microwave reaction tubes as they are delicate and expensive to replace.
Place methyl benzoate (1.00 mL) in a microwave reaction tube and add 5% aqueous
sodium hydroxide (10 mL). Add a magnetic stirrer bar, then screw on the cap and place your
tube in the microwave turntable. Record the position number of your reaction tube on the
turntable. When all of the tubes have been added, your instructor will place the turntable into the
microwave unit, close the door and select the correct file-setting for your reaction (Ester.rot).
The program will take 12 minutes to run, followed by a 5 min. vent and cool down program. On
completion, your instructor will open the microwave door and remove the turntable. Carefully
remove your reaction tube, and empty the contents into a beaker. Cool the contents to room
temperature, and acidify the solution with about 2 mL of concentrated HCl. As acidification
proceeds, solid benzoic acid will precipitate. Be sure to check that the final solution is acidic by
using pH paper. Cool the mixture in an ice bath and suction filter the benzoic acid. After the
benzoic acid has dried sufficiently, weigh the solid, take its melting point and calculate the
percent yield.
IMPORTANT INFORMATION ABOUT THE REPORT:
The report for this experiment will follow the usual format for synthesis reactions. Be
sure the percent yield calculation is carefully done. Also, record the melting point range of the
final product and compare that melting point to the reported melting point of benzoic acid.
Using these data, discuss the relative success of the experiment. Also, be sure to critique the
effectiveness of using microwave heating to cause the reaction to occur. Draw a mechanism for
the conversion of the methyl ester to the corresponding carboxylic acid using the curved arrow
formalism.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
40
LAB 13: ANALYSIS OF CARBOHYDRATES
PURPOSE:
Continuing with the techniques of qualitative organic analysis, the student will do test
tube experiments to learn about the different classes of carbohydrates and natural sweeteners.
IMPORTANT STRUCTURES:
Monosaccharides
Aldohexose:
CHO
CHO
CHO
HO
H
H
HO
H
HO
H
OH
H
OH
H
OH
H
HO
H
H
OH
HO
H
H
OH
H
CH2OH
CH2OH
D-Mannose
OH
OH
CH2OH
D-Galactose
D-Glucose
Aldopentose:
Ketohexose:
CH2OH
CHO
O
H
HO
OH
H
H
OH
H
OH
CH2OH
D-Fructose
HO
H
H
OH
CH2OH
D-Xylose
41
Disaccharides
Lactose (from galactose and glucose, shown in aldehyde form)
OH
CH2OH
OH
O
HO
CHO
O
HO
CH2OH
OH
OH
Maltose (from 2 glucose units, shown in aldehyde form)
CH2OH
O
HO
CH2OH
HO
OH
O
OH
CHO
HO
OH
Sucrose (from glucose and fructose)
CH2OH
O
CH2OH
HO
HO
O
OH
OH
O
CH2OH
OH
BACKGROUND INFORMATION:
Sweetening the foods and drink humans consume is very important to the food chemist.
Natural caloric sweeteners have been known for many centuries. Within the last century there
has been a growing importance to reduce the calories humans consume to control weight. A few
successful non-caloric sweeteners have been developed and reached commercial importance.
The first of these to be introduced around the 1950’s was calcium cyclamate. This product was
42
abruptly taken off the market in the late 1960’s when a connection between its use and bladder
cancer was shown. Another artificial sweetener developed around that time and still in use is
saccharin. This successful sweetener leaves an unpleasant after taste in some people so it is not
an ideal substitute. During the 1980’s aspartame (NutraSweet) was introduced. This sweetener is
a methyl ester of an amino acid dimer. It has been very successful. The latest artificial sweeter is
a chlorinated sucrose molecule which is found in sucralose (Splenda).The above mentioned
compounds are not carbohydrates. They are artificial sweeteners.
Carbohydrates are polyhydroxy aldehydes or ketones or compounds that can be
hydrolyzed to polyhydroxy aldehyles or ketones. Carbohydrates which contain one carbonyl
group or potential carbonyl group (which would result from the hydrolysis of a hemiacetal
linkage) are called monosaccharides. Monosaccharides generally contain 4 to 7 carbon atoms.
When two monosaccharide molecules bond together via an acetal or hemiacetal linkage, a
disaccharide is formed. Three monosaccharide molecules would give a trisaccharide, etc. If a
very large number of monosaccharide molecules join together, a polysaccharide (such as:
cellulose, starch or glycogen) is formed. These larger molecules can be split apart into the
simpler units via acid hydrolysis or enzymatic action. The lower molecular weight carbohydrates
(mono, di and trisaccharides) are often sweet to varying degrees and are often called sugars.
Monosaccharides can be further classified by the number of carbon atoms in the
molecule. The nomenclature ending suffix for carbohydrates is -ose. A five carbon
monosaccharide would be a pentose; a six carbon one would be a hexose, etc. If the carbonyl
group is an aldehyde, the monosaccharide is a aldose. The ketone containing monosaccharides
are ketoses. The six carbon aldehyde sugar known as glucose is an example of an aldohexose.
With 4 chiral centers in this molecule, glucose has 16 stereoisomers. This number rises to 32
when glucose forms an intramolecular hemiacetal ring.
Carbohydrates can also be classified as reducing or nonreducing. If the carbohydrate can
be easily oxidized, it is a reducing carbohydrate. If not, it is a nonreducing carbohydrate.
Reducing carbohydrates have an aldehyde group or a hemiacetal linkage.
Since carbohydrate molecules contain a large number of polar alcohol groups, the lower
carbohydrates are mostly water soluble. As the molecular weight increases, water insolubility
can arise. Carbohydrates are often difficult to crystallize.
The tests described below will give information about the class of carbohydrate to which
the test substance belongs. Perform the tests as described below and draw conclusions about the
unknowns that were assigned. It is possible that you may not be able to fully identify a given
unknown but clearly state the conclusions that can be made.
EXPERIMENTAL PROCEDURE:
Perform the following identification tests on each of the six sugars to be tested: glucose,
fructose, xylose, sucrose, lactose, and maltose. For your classification tests, you will be using 1
% solutions of each of the sugars.
1) Red Tetrazolium Test
This test distinguishes between reducing and non-reducing sugars. In clearly
labeled test tubes, place one drop of the sugar to be tested, and add the red tetrazolium solution
(1 mL) and 3 M sodium hydroxide solution (1 drop). Put the tube in a hot water bath and
estimate the time that it takes for a color to appear.
43
2) Barfoed’s Test
This test distinguishes between mono and disaccharides that are reducing sugars.
In clearly labeled test tubes, place the sugar to be tested (1 mL) and add the Barfoed’s reagent
(0.5 mL). Put the tube in a hot water bath and estimate the time that it takes for a red precipitate
to form.
3) Bial’s Test
This test distinguishes between pentoses and hexoses. In clearly labeled test tubes,
place the sugar to be tested (1 mL), add the Bial’s reagent (1 mL) and a boiling chip. Heat the
tubes in a sand bath and estimate the time that it takes for a color to form. Also note the intensity
of the color that develops. As a standard of reference, add the Bial’s reagent (1 mL) to water (1
mL) and heat that along with your samples for comparison.
4) Seliwanov’s Test
This test distinguishes between aldohexoses and ketohexoses. Place Seliwanov’s
reagent (1 mL) in each clearly labeled test tubes. Add the sugar to be tested (5 drops), agitate to
mix, then heat in a water bath for 5 minutes. Note the color and its intensity.
IMPORTANT INFORMATION ABOUT THE REPORT:
You will be assigned a number of unknowns to determine using the tests described
above. For your report, be sure to identify by unknown number and class name for each
unknown, if possible. After you give this information, be sure to carefully and completely
describe how you reached your decision. Tell the tests you did to determine what the compound
was and how you eliminated other possibilities.
END OF EXPERIMENT
© 2010 Anderson, Shine, Carberry, and Carreon
44
APPENDIX A: QUALITATIVE ORGANIC ANALYSIS
QUALITATIVE ORGANIC ANALYSIS
SIM-ORG PROGRAM HELP SECTION
LONG VERSION
Dr. Scott Frees and Dr. Robert Shine
Ramapo College of New Jersey
Mahwah, NJ 07430
CONTENTS:
Introduction
Strategy for Identifying and Unknown
Solubility Classification
Functional Group Classification Tests
Derivative Formation and Use
Final Identification of an Unknown Substance
This simulation program includes:
12 organic chemistry functional groups
24 classification tests
21 derivative tests
500 unknowns
GENERAL INTRODUCTION TO QUALITATIVE ORGANIC ANALYSIS
There are two methods for identifying the structure of an unknown organic compound.
The first and older method is to run classification tests to identify the functional group of the
compound followed by the production of one or more derivative compounds to confirm the exact
nature of the unknown. The second method is to determine the spectral properties of the
unknown using mainly infrared and proton magnetic resonance spectroscopy. The first method
will be covered in this simulation program. This program has 12 different functional group
classes and 500 different unknowns. It is planned that the second method will be covered in a
later revision of this program.
The general method to determine the identity of an unknown substance by classical
methods is to gather some introductory information about the compound. Note the odor, color,
and melting or boiling point of the material. Then find its solubility characteristics by doing a
solubility classification as described below. From the information obtained from the solubility
classification run appropriate functional group tests to identify the group to which the unknown
belongs. Then the unknown is converted into one or more different solids called derivatives.
Consulting tables of derivative melting points one can then identify the exact identity of the
unknown compound.
In order to intelligently conduct the functional group classification tests a solubility
classification is usually done first to narrow down the possible functional group possibilities.
A problem may arise when an unknown substance has two or more functional groups in
the molecule. This may lead to confusion when interpreting the functional group and could lead
45
one to the wrong table of derivatives. Such unknowns are more difficult to identify. There are a
few such compounds in this simulation program.
STRATEGY FOR IDENTIFYING AN UNKNOWN
The following steps should be taken to identify an unknown compound:
1. Perform a solubility classification test to determine the possible functional group classes
to which the unknown may belong.
2. Narrow the choices of possible functional groups to one group by performing appropriate
functional group tests.
3. Make one or more derivatives to finally determine the exact identity of the unknown.
The above approach should lead to a successful identification of an unknown about 80 % of the
time. In other cases, the unknown may pose difficulties that would require imagination and
careful analysis of the data to be successful in its identification.
SOLUBILITY TEST ANALYSIS:
Obtain the solubility class for the assigned unknown. Shown below is a list of possible
functional groups for each solubility class. This classification method is not exact and may need
further thought and imagination in certain cases. These solubility classes and their consequences
can be summarized below:
S1
These are very polar compounds which consist of salts of carboxylic acids or amines. It is
also possible the compound is of low molecular weight and has many polar functional groups
such as a carbohydrate.
S2
These compounds are low molecular weight (generally less than 5 carbons) with a polar
functional group such as carboxylic acid, amine, alcohol, aldehyde, or ketone.
A1
Higher molecular weight carboxylic acids fall into this class.
A2
Phenols show this kind of solubility.
B1
Primary, secondary and tertiary amines fall into this class. However, if there are two or
more phenyl groups on the nitrogen, the amine will probably not be basic enough to form the salt
and will, then, be insoluble.
N1
These are higher molecular weight compounds (generally more than 9 carbons)
containing an oxygen atom.
N2
These are medium size molecules (generally containing from 5 to 9 carbons) containing
an oxygen atom.
IN
These are neutral compounds. Alkyl halides and alkanes fall into this class.
FUNCTIONAL GROUP ANALYSIS:
Below are listed 24 chemical tests that could be used to help identify an unknown. The
tests are listed in numerical/alphabetical order.
23. Introduction to qualitative tests
24. 2,4-dinitrophenylhydrazone
25. Acetyl chloride
26. Basic hydrolysis
27. Beilstein
28. Benedict
29. Bromine in carbon tetrachloride
30. Ceric nitrate
46
31. Chromic acid
32. Combustion
33. Ferric chloride
34. Ferric hydroxamate
35. Ferrous hydroxide
36. Hinsberg
37. Hydroxylamine hydrochloride
38. Iodoform
39. Lucas
40. Nitrous acid
41. pH in ethanol/water
42. Potassium permanganate
43. Silver nitrate in ethanol
44. Sodium fusion
45. Sodium iodide in acetone
46. Solubility
47. Tollens
DERIVATIVE USAGE:
Below are listed 21 derivatives that could be prepared from various unknowns to help in
a final determination of the unknown. The derivatives are listed in numerical/alphabetical order.
22. Introduction to derivative use
23. 1-naphthylurethane
24. 2,4-dinitrophenylhydrazone
25. 3,5-dinitrobenzoate
26. Acetamide
27. Acid from hydrolysis
28. Amide
29. Anilide
30. Benzamide
31. Benzenesulfonamide
32. Bromo derivative
33. Methiodide
34. Neutralization equivalent
35. Oxime
36. Phenylhydrazone
37. Phenylurethan
38. Picrate
39. p-Nitrobenzyl ester
40. p-Nitrophenylhydrazone
41. p-Toluenesulfonamide
42. p-Toluidide
43. Semicarbazone
47
SOLUBILITY CLASSIFICATION
The solubility of an organic compound in various solvents can give valuable information
about the unknown. The general rule of 'like dissolves like' or 'polar compounds dissolve more
readily in polar solvents' is useful. Also, organic acids (such as carboxylic acids and phenols)
react with bases to form water soluble salts and organic bases (such as amines) react with acids
to form water soluble salts. It should be noted that the polarity of an organic compound is
increased by the kind and number of polar functional groups in the molecule and that the polarity
decreases as the size of the non polar aliphatic group in the molecule increases.
With this background, one begins the solubility classification by adding 3 drops or 3 mg
of the unknown to 3 mL of water and shaking the mixture. If the unknown dissolves, it is a polar
compound and in placed in solubility group S1. An unknown in class S1 is then tested as above
using ether as the solvent. If it dissolved in both water and ether it is then placed in class S2. For
unknowns that do not fall into either class S1 or S2, the unknown’s solubility in 5% sodium
bicarbonate is determined. If it is soluble, the unknown is placed in class A1. If it is not soluble,
the solubility in 5% sodium hydroxide is studied. If it is soluble at this point, the unknown
belongs in class A2. If an unknown is insoluble to this point it is next tested for solubility in 5%
hydrochloric acid. Compounds soluble in 5% hydrochloric acid are placed in solubility class B1.
For compounds insoluble to this point the next solvent to try is concentrated sulfuric acid.
Unknowns soluble in only this acid are placed in solubility class N1. A further distinction can be
made for compounds soluble in concentrated sulfuric acid by testing their solubility in 85%
phosphoric acid. Such compounds that are soluble in 85% phosphoric acid are placed in class
N2. Finally, compounds insoluble to this point are placed in class IN.
These solubility classes and their consequences can be summarized below:
S1
These are very polar compounds which consist of salts of carboxylic acids or amines. It is
also possible the compound is of low molecular weight and has many polar functional groups
such as a carbohydrate.
S2
These compounds are low molecular weight (generally less than 5 carbons) with a polar
functional group such as carboxylic acid, amine, alcohol, aldehyde, or ketone.
A1
Higher molecular weight carboxylic acids fall into this class.
A2
Phenols show this kind of solubility.
B1
Primary, secondary and tertiary amines fall into this class. However, if there are two or
more phenyl groups on the nitrogen, the amine will probably not be basic enough to form the salt
and will, then, be insoluble.
N1
These are higher molecular weight compounds (generally more than 9 carbons)
containing an oxygen atom.
N2
These are medium size molecules (generally containing from 5 to 9 carbons) containing
an oxygen atom.
IN
These are neutral compounds. Alkyl halides and alkanes fall into this class.
The results of a solubility classification should not be strictly interpreted as there are
many overlaps. Use the results of this classification only as a focus into which classification tests
should be done first.
FUNCTIONAL GROUP CLASSIFICATION TESTS
INTRODUCTION TO QUALITATIVE TESTS - The first test that should be done is a
solubility test to determine the class or classes to which the unknown belongs. From the results
48
of the solubility tests, some idea of the type of organic compound should be evident. If the
solubility test results put the unknown substance in the ‘Neutral’ section, it is recommended that
the classification tests be done in this order: aldehydes, ketones, alcohols, esters, amides, nitriles,
ethers, alkenes and alkynes. Select a test from the list of tests that would help confirm the
presence or absence of the suspected functional group class. Do as many tests that may be
necessary to absolutely confirm the functional group to which the unknown belongs. Be careful
to interpret correctly the test results for those unknowns that may contain two or more functional
groups. At that point, proceed to the preparation of derivatives to identity the exact identity of the
unknown.
2,4-DINITROPHENYLHYDRAZINE TEST (for aldehydes and ketones) - This test will be
positive for an aldehyde or ketone as indicated by the formation of a yellow, orange or red
precipitate which is called a 2,4-dinitrophenylhydrazone. This precipitate can also be used as a
derivative for the unknown if its melting point is determined (see below for derivative use). The
color of the precipitate can help further identify the extent of conjugation for the carbonyl group.
Highly conjugated aromatic aldehydes or ketones generally give red solids whereas non
conjugated carbonyl compounds give yellow products.
ACETYL CHLORIDE (for acidic hydrogen compounds) - This test will help identify carboxylic
acids, phenols and alcohols. A positive test will be noted by the evolution of heat which may be
hard to detect. So, this test may give false positive or negative tests depending on the expertise of
the person doing the test. In some cases, a solid (usually white) may form. If this happens, the
solid, if isolated and its melting point is determined, could be used as a derivative for the
unknown. If water is present in the unknown, the test will probably give a false positive test as
acetyl chloride reacts vigorously with water.
BASIC HYDROLYSIS (for amides, esters and nitriles) - Amides and esters can be hydrolyzed
by heating in a sodium hydroxide solution. This reaction pH gives the acid as a water soluble
carboxylate salt. Acidifying this solution with concentrated hydrochloric acid would result in a
precipitate if the carboxylic acid is water insoluble. If this precipitate is formed, it should be
filtered and used as a derivative for the unknown.
BEILSTEIN TEST (for halogenated compounds) - Placing a small amount of an organic
compound on the end of a copper wire and heating it in the open flame of a Bunsen burner
results in a transient green color in the flame if the compound contains a halogen atom. If the
unknown is volatile, it may evaporate before it burns resulting in a negative test.
BENEDICT TEST (for aldehydes and sugars) - When easily oxidized organic compound (such
as aldehydes and reducing sugars) is heated in Benedict’s solution (which is a blue solution
containing a complexed copper (II) ion) a brick red precipitate of cuprous oxide forms. If the
unknown is not soluble in the reagent a negative test may be observed due to the lack of a
reaction.
BROMINE IN CARBON TETRACHLORIDE (for alkenes and alkynes) - When a solution
bromine in carbon tetrachloride is added drop wise to an colorless unknown compound, the
49
brownish color of elemental bromine disappears as the bromine adds to the unsaturated organic
compound.
CERIC NITRATE (for alcohols and phenols) - Alcohols with 10 carbons or less will give a red
color with ceric nitrate solution whereas phenols will give a green-brown to brown precipitate.
Easily oxidized compounds may destroy the ceric nitrate solution before the test results may be
observed.
CHROMIC ACID (for aldehydes, primary and secondary alcohols) - Easily oxidized compounds
convert the red chromium (VI) ion to a green chromium (III) precipitate.
COMBUSTION (for flammable or combustible organic compounds) - When a few milligrams of
an organic liquid or solid are placed directly into a Bunsen burner flame they often burn. Note
that highly halogenated organic compounds may not burn. Very volatile compounds may
evaporate before burning or burn very rapidly. The manner in which a compound burns can give
some information about its nature. Highly oxygenated compounds burn with a blue flame,
aliphatic compounds give a yellow flame and aromatic compounds give a sooty flame.
FERRIC CHLORIDE (for phenols) - Some (but not all) phenols give a color when ferric
chloride solution is added. This test is not a definitive one and the results should be carefully
evaluated.
FERRIC HYDROXAMATE (for esters, acid chloride and anhydrides) - Esters of carboxylic
acids give a magenta color with this reagent. Acid chloride and anhydrides give a magenta or
burgundy color with the test reagent.
FERROUS HYDROXIDE (for nitro compounds) - Most compounds that contain a nitro group
will give a brown to red-brown precipitate of ferric hydroxide by oxidation of ferrous hydroxide.
HINSBERG TEST (to distinguish primary, secondary and tertiary amines) - Benzenesulfonyl
chloride can be used to distinguish primary, secondary and tertiary amines. The amine functional
group must be confirmed before this test can be performed as the test will give very confusing
results with any other functional group. Primary amines give a solid benzenesulfonamide product
that is soluble in 5% sodium hydroxide. Secondary amines give a solid benzenesulfonamide
product that is insoluble in 5% sodium hydroxide. Tertiary amines do not react with
benzenesulfonyl chloride.
HYDROXYLAMINE HYDROCHLORIDE (for aldehydes and ketones) - Aldehydes and most
ketones give a red color when added to a solution of hydroxylamine hydrochloride in ethanolwater that has a universal indicator added.
IODOFORM TEST (for methyl carbonyl compounds) - This test is mainly used to identify
methyl ketones. The iodoform regent iodinates the methyl group which then cleaves in the basic
solution. One should confirm the presence of a carbonyl group in the unknown before this test is
done as misleading results could occur with other compounds. For example, acetaldehyde and
50
alcohols that have a methyl group bonded to the C-OH group can also give a positive test since
such an alcohol can be oxidized to a methyl ketone by the iodoform reagent.
LUCAS TEST (to distinguish primary, secondary and tertiary alcohols of six carbons or less) - A
solution of zinc chloride in aqueous hydrochloric acid can be used to distinguish primary,
secondary and tertiary alcohols. The unknown compound must be soluble in the reagent in order
for the test to be valid. When a tertiary alcohol is added drop wise to the reagent, an immediate
second layer of a liquid alkyl chloride is formed. Secondary alcohols form a second layer of the
insoluble alkyl chloride in three to 5 minutes. Primary alcohols are unreactive with the Lucas
reagent.
NITROUS ACID (to distinguish primary, secondary and tertiary amines) - Primary aromatic
amines give nitrogen gas evolution with the nitrous acid reagent. Other aromatic amines can
undergo coupling reactions to form colored products.
pH IN ETHANOL (to distinguish low molecular weight acidic or basic compounds) - The pH of
compounds that are soluble in water or aqueous alcohol can be measured. If the pH is in the acid
range the compound can be a carboxylic acid, acid chloride or anhydride. If the pH is in the basic
range, the compound may be an amine. Organic salts may hydrolyze in water which can lead to
acidic or basic solutions.
POTASSIUM PERMANGANATE (for compounds that can be oxidized) - Organic compounds
that can be readily oxidized will convert the purple permanganate ion to a brown precipitate of
manganese dioxide. Such organic compounds include: aldehydes, reducing sugars, primary or
secondary alcohols and some alkenes and alkynes.
SILVER NITRATE IN ETHANOL (for alkyl halides that can undergo S N1 reactions) - Tertiary
alkyl halides will give a white to yellow silver halide precipitate with this reagent. Some
secondary halides will react more slowly. Aryl and vinyl halides do not react.
SODIUM FUSION (for compounds that contain halogen, nitrogen or sulfur) - When an organic
compound is placed in molten elemental sodium the molecules are violently destroyed. Any
halogen, nitrogen or sulfur in the original molecule is converted to ionic materials which are then
identified. The halide is identified by precipitation with silver ions. The sulfide ion is identified
by precipitation with lead ions. The cyanide ion formed from the nitrogen in the molecule is
converted into Prussian blue by ferrous sulfate.
SODIUM IODIDE IN ACETONE (for alkyl halides that can undergo SN2 reactions) - Primary
and some secondary alkyl chlorides or bromides will give a precipitate of sodium iodide in the
reagent. Alkyl iodides will not give a precipitate. Aryl or vinyl halides do not react.
SOLUBILITY (for general classification of organic compounds) See SOLUBILITY
CLASSIFICATION section above.
TOLLENS TEST (for aldehydes and reducing sugars) - Water soluble aldehydes and reducing
sugars give a silver mirror or black precipitate of elemental silver with the Tollens reagent.
51
DERIVATIVE FORMATION AND USE
INTRODUCTION TO DERIVATIVE USE - Derivative Tests - Once the classification
tests have indicated an organic family of compounds (i.e. an aldehyde), one can see if derivatives
of the unknown can be synthesized to help in its identification. Based on the results of the
classification tests, the correct derivative tests to use can be determined. On selecting the relevant
test, the results will be illustrated. If the derivative test is positive, it is evidence that the correct
family of compound has been chosen, and the melting point of the derivative should be recorded
on a data sheet. Order all the derivative tests relevant to the search (i.e. for an aldehyde, obtain
the melting points of both the semicarbazone and 2,4-dinitrophenylhydrazine derivatives) and
then proceed to the final identification of the unknown substance.
1-NAPHTHYLURETHANE DERIVATIVE - (for alcohols and phenols)
2,4-DINITROPHENYLHYDRAZONE - (for aldehydes and ketones)
3,5-DINITROBENZOATE - (for alcohols)
ACETAMIDE - (for primary and secondary amines)
ACID FROM HYDROLYSIS - (for acid chloride, anhydride, ester, amides, and nitriles)
AMIDE - (for carboxylic acids, acid chlorides, and anhydrides)
ANILIDE - (for carboxylic acids, acid chlorides, and anhydrides)
BENZAMIDE - (for primary and secondary amines)
BENZENESULFONAMIDE - (for primary and secondary amines)
BROMO DERIVATIVE - (for phenols)
METHIODIDE - (for tertiary amines)
NEUTRALIZATION EQUIVALENT - (for acids, amides, esters and nitriles)
OXIME - (for aldehydes and ketones)
PHENYLHYDRAZONE - (for aldehydes and ketones)
PHENYLURETHAN - (for alcohols and amines)
PICRATE - (for tertiary amines)
p-NITROBENZYL ESTER - (for carboxylic acids)
p-NITROPHENYLHYDRAZONE - (for aldehydes and ketones)
52
p-TOLUENESULFONAMIDE - (for primary and secondary amines)
p-TOLUIDIDE - (for primary and secondary amines)
SEMICARBAZONE - (for aldehydes and ketones)
FINAL IDENTIFICATION OF AN UNKNOWN SUBSTANCE
Tables of organic substances can be used to identify the unknown based on the results of
the classification tests and the derivative melting point results.
TABLES OF UNKNOWNS - Once the derivative melting point data have been recorded, enter
the Tables of Unknowns by selecting the suspected functional group class. Here a list of organic
compounds separated by type will appear. Select the family to which the unknown belongs. A
list of all the compounds of that type, presented in order of increasing boiling/melting point will
appear. Also listed are the melting points of any derivatives that can be synthesized from the
class of the unknown compound. By matching the table data with the unknown compound data
obtained above, one can identify the unknown.
ANSWER TRIAL - Based on all the melting point data in the Tables of Unknowns, one will now
have an idea of what the unknown sample is. To see if you are correct, you can enter it into the
program by selecting Answer Trial. Make sure that you select the compound correctly, exactly as
it appears in the table of unknowns. If you are correct, a congratulation message will appear. If
you are wrong, first re-check your data for the unknown. If it is still incorrect, then you will need
to go back into the program in order to correctly identify the unknown sample.
© 2010 Scott Frees and Robert Shine
53
APPENDIX B: SAFETY ISSUES
INTRODUCTION:
A very important aspect of laboratory work is working safely. It is your responsibility to
yourself and the other people in the laboratory to work in a serious and careful manner. If you
are not sure about the dangers involved in what you are assigned to do, be sure to ask the
Instructor before you begin. You should consult the material safety data sheets (MSDS) for those
chemicals you will be working with before coming to the lab. You can find MSDS data by
typing the chemical name followed by MSDS in a Google search box. For example msds data for
acetone could be found by typing acetone msds in the search box.
If you have allergies, you should consult your Allergist for advice in working with
organic chemicals. If you are pregnant or become pregnant, you should consult your doctor for
advice in working with organic chemicals.
There are risks involved with all activities you do. By knowing what those risks are and
taking prudent actions, you can lessen the dangers you face and thereby lead a relatively safe life.
The dangers you are likely to face in the organic chemistry laboratory are due to:
1. Equipment
2. Toxic chemicals
3. Flammable chemicals
EQUIPMENT:
You will use glassware, plastic ware, and electrical heating equipment in the lab. As you
know, glass items can break and cause cuts that can be minor or severe. You should exercise care
when handling glassware to minimize breakage. If a glass item breaks, notify the Instructor who
will then use a broom and dustpan to clean up the area. Broken or discarded glassware must be
placed in the separate container that is marked for broken glass. No other items other than
glassware should be placed in that container.
Plastic ware generally has no safety concerns and is safe to use.
Heating in the lab will generally be done using electrical heating equipment such as hot
plates and heating mantles. We will not use Bunsen burners in the laboratory. We may use steam
baths on occasion. Steam can cause a bad scalding burn. Hotplates and heating mantles do not
change appearance when they are hot so you should always assume they are hot until proven
otherwise. There can also be an electrical shock hazard with any electrical equipment. Electrical
outlets in the organic chemistry laboratory are protected by ground fault interrupter circuit
breakers.
Also be aware that heating equipment can be hot enough to exceed the flash point of a
chemical and can start a fire. Chemicals that have a low flash point can be ignited by a warm hot
plate. Evaporating diethyl ether from a beaker on a hotplate caused a fire in our organic
chemistry laboratory many years ago.
TOXIC CHEMICALS:
Eye protection must be worn in the laboratory whenever anyone in the lab is working
with chemicals. Only department approved eye goggles can be used. If, at any time, you suspect
that a chemical got onto your skin or eyes, immediately wash the affected area with plenty of
cold water for a significant period of time. Be sure to notify the Instructor after you begin the
54
washing process. Chemicals that are immediately washed from the skin will cause less damage
than those that are allowed to remain on the skin until you feel pain. So, even if you feel no pain,
wash the affected area immediately.
Many chemicals have toxic properties which vary from compound to compound. The
best source of information about the toxic properties of chemicals you will use is the material
safety data sheet (msds) for that chemical. Be aware that chemicals can enter the body by
inhalation, ingestion, absorption or injection through the skin. You should use gloves to protect
the skin and should rinse your hands after handling chemicals. When you leave the lab you
should thoroughly wash your hands.
Ingestion of chemicals can be avoided by not putting anything in your mouth during the
laboratory period. Never pipette by mouth; use approved suctioning devices. Never eat or drink
any food in the lab, including chewing gum, as it could have been contaminated.
Inhalation of volatile chemicals can be avoided by working in the fume hood. Try to
minimize the time a volatile chemical will be exposed to the air outside the hood. Weigh such
substances quickly and move them immediately to the hood.
Some chemicals used in the lab are corrosive. Generally these include acids and bases.
The more concentrated the acid or base, the more corrosive it will be. So use extreme care with
concentrated sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and sodium hydroxide
solutions. Nitric acid will cause orange patches to appear on the affected skin in one to three
days. This orange patch will slowly wear off. Silver nitrate will cause black stains to appear in
the affected area within a few hours after exposure and will wear off in a few days. Volatile
organic solvents that enter the body can cause systemic poisoning. Often, the liver or kidneys are
affected. Be sure to read the material safety data sheet for specific information about the
chemicals with which you are working.
FLAMMABLE CHEMICALS:
Many organic chemicals can burn. Halogenated organic compounds are usually less
flammable than others but they tend to be more toxic, especially to the liver. Compounds with a
high percentage of carbon (such as aromatic hydrocarbons) burn with a very black sooty flame.
Other hydrocarbons burn with a yellow flame and as the oxygen content of the compound
increases, the flame becomes more bluish.
In order to have a fire start, three things are needed. You must have a compound that can
burn, an oxidizing material such as air, and an ignition source that will raise the temperature of
the flammable substance above its flash point.
Of real concern is whether or not a compound can cause a fire. There are terms whose
meaning you need to know. These terms are: nonflammable, inflammable, flammable, and
combustible. Nonflammable means the compound will not burn under reasonable conditions.
They pose no fire hazard. Water is such a substance. Inflammable is a very bad choice for a
word. The dictionary defines inflammable as "capable of being set on fire; combustible."
Inflammable does not mean "not flammable." The word inflammable should not be used. A
flammable substance is "one that is easily set on fire" and a combustible substance is "capable of
being set on fire." Flammable substances, with their lower flash points, pose a more serious fire
hazard than combustible substances. Gasoline would be considered flammable and wood would
be considered combustible. So, use care when working with flammable and combustible
substances, especially with flammable substances.
© 2010 Anderson, Shine, Carberry, and Carreon
55
APPENDIX C: COMMENTS ABOUT WRITING STYLE
Before you begin writing lab reports for this course, you should carefully study the
following statements, which are presented to help you achieve good grades. Failure to use this
advice could result in a lower lab grade.
1. On all written work you submit, place your name, the full descriptive name of the experiment,
and the day of the week (that is, Monday, Tuesday, Wednesday, or Thursday) that you have lab.
2. Reports are due at the beginning of the next class meeting. If you computer dies, submit the
report on time, neatly handwritten. Reports cannot be submitted electronically unless allowed by
your Instructor.
3. Use correct grammar and spelling. Use adjectives, nouns and verbs correctly. Use scientific
terms correctly. Proofread your report and check all spelling as spell checkers do not recognize
the misuse of words (such as to, too and two).
4. Use terms (especially scientific terms) correctly. Do not misspell the name of a chemical.
Failure to use technical terms correctly will have a definite negative impact on your report grade.
For example, do not report the boiling point of a solid; report its melting point.
5. Do not be vague or overly explicit. Give only the important data, observations and
conclusions.
6. Your report should have a correct, logical flow. For example, give the data before the
conclusions that are made.
7. When giving a measurement, be sure to include both the number (with the correct number of
significant figures) and correct units.
8. Pay attention to the correct use of significant figures. See Appendix D for more information
about the correct use of significant figures.
9. Do not start a sentence with a digit. Spell out any numbers that start a sentence.
10. Use the third person, passive voice in science report writing.
11. The data page that you submit when you leave the lab is part of your lab grade. The data page
must be clearly presented, as neat as possible, and must give all the critical measurements
(numbers and units) you made in the lab. Computations of results may be left until the final
report is written if they are difficult to do. Simple computations may be included with the data
sheet.
12. Be sure that each section in the report has an introductory sentence.
13. Cite all references used and be exact in giving each reference.
14. The introduction section must have structures of important compounds or a chemical
equation drawn early in the section.
15. The introduction section should deal with the theory of the experiment and not give
experimental details.
16. The experimental section can be brief with a reference to the lab manual. You need add only
the changes you made that differed from the lab manual.
17. As much as possible, tabulate data and place them near the text that describe it. Be sure the
table has a meaningful title and that the data are presented in a clear manner.
18. Do not describe a math formula in text. Draw the formula and separate it from the text by at
least one line.
19. For results that are computed from lab data, be sure to show how the computation was done.
That is, show the math used. When doing computations in the lab report, show the general
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formula and then show the formula with your actual data to show how you obtained your result.
Set the mathematics away from text so it stands out.
20. Fully explain the data. Do not leave any critical data out of the report. If you calculated the
amount of a substance by measuring the weight of a container empty and then again with the
sample in it, both weights must be in the report along with the final weight.
21. Be sure data, calculations and conclusions are tied together. If these items are in different
parts of the report, be sure to tell the reader where they can be found.
22. All data in the lab report should be able to be traced back to the experimental data you
recorded on the data sheet you submitted. Do not take any shortcuts in data handling. You must
show all relationships in a logical, orderly manner, and you must show how results were
calculated.
23. When giving melting point or boiling point data, be sure to report these data as a range, and
be sure to give the accepted literature values in parentheses immediately after your experimental
data.
24. The conclusion section may be brief but should tell what the objectives of the experiment
were and if they were achieved.
25. Do not report a percent error unless told to do so. We measure percent recovery or percent
yield. Be sure you know the difference between these terms.
26. Repeating errors, such as the misspelling of a chemical, will be noted only once when reports
are graded.
27. Do not capitalize a chemical name unless it is the first word in the sentence.
28. Mass is not used as a verb in this course. A chemical can be weighed but not massed. Also,
precipitates are filtered, not funneled.
29. Two words are often misused in this course. The first is 'separate' which is often misspelled
with an 'e' after the 'p'. Fortunately, spell checkers fix this error. The other misused word is 'vial'
which many students write as 'vile'. A spell checker does not repair this mistake. The dictionary
defines 'vile' as: "mean, worthless, unclean, repulsive, bad." The same dictionary defines the
homonym 'vial' as: "a small vessel." Be sure to use these two terms correctly.
30. Do not use the first or second person in scientific writing. Do not use I, we, or you.
31. A rewrite of a previously graded lab report will not be accepted unless it was authorized and
agreed upon by the Instructor before it was done.
32. More information about good report writing style for chemists can be found on the Web by
doing a Google search on ‘writing style for chemists’.
© 2010 Anderson, Shine, Carberry, and Carreon
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APPENDIX D: MEASUREMENTS AND SIGNIFICANT FIGURES
INTRODUCTION:
A very important aspect of laboratory work is making and reporting measurements
carefully. A significant part of your grade will be based on how you gather and report data. You
will need to know which measurements will need to be made carefully and which are less
important and can be made quickly with less accuracy.
There are three terms that you will need to know and understand: precision, accuracy, and
significant figures. These terms have similar meaning and are often confused.
Precision: The ability of repeated measurements to have the same value. If you weigh an
item three different times, the number of grams should be exact or very close for all the
measurements.
Accuracy: The agreement of a measurement with the accepted value reported for that
value. If you measure the density of water at 4 degrees Celsius, it should be 1.00 g/mL.
Significant figures: The number of digits that can be reported for a measurement. If you
weigh some item on the top loading balance in our laboratory, it can be recorded to the third
decimal place if using units of grams, such as, 1.234 g.
In this laboratory course, the correct use of significant figures will be the most important
of the three. Accuracy will be the next most important and precision will generally be
disregarded as you will usually not make repeated measurements of the same data item.
SIGNIFICANT FIGURES:
The number of significant figures you give in your lab report is governed by the limits of
the measuring devices you use and the care you exercise in making a measurement.
Mathematical manipulation of data can never increase the number of significant figures in your
result.
You will need to know what measurements are important and which are not. Do not
waste time in making a very careful measurement on some less significant piece of data. For
example, the exact amount of a reagent is needed but the precise volume of solvent in which it is
dissolved is often not needed.
Be sure to record important data to the level of precision the measuring instrument
allows. If the directions tell you to measure out exactly 0.500 g of a compound, then you will
have to spend some time to carefully get 0.500 g. However, often the directions will say to
measure about 0.500 g of a compound. Here, you can quickly weigh out an amount that is
approximately 0.500 g but you must record your exact weight. For example, you may have
weighed 0.476 g. You would then use that figure (0.476 g) in your report and further
calculations.
It is important that you know the difference between 0.05 and 0.050. The first of these
(0.05) has one significant figure while the second (0.050) has two significant figures. A zero
used to place the decimal point is not a significant figure. So, if you carefully weighed out 0.500
g and wrote it as 0.5 g or 0.50 g, you would be wrong. You must show all the significant figures
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allowed by the measurement you made along with the correct units such as grams (g), milligrams
(mg), milliliters (mL), etc.
In any measurement, the last significant figure has an uncertainty associated with it.
Often you will see the balance going up and down over time in the last decimal place. So a
measurement such as 0.476 g really is 0.476  0.001 g.
In using conversion factors such as 1 pound/453.6 g, the number 1 is exact and can be
assumed to have the same number of significant figures as the other value. So here, the
conversion factor is 1.000 pound/453.6 g. Also note that every conversion factor equals one so
the reciprocal also is true. That is, 453.6 g/1 pound is also true. In all your calculations, be sure to
show the numerical data and the correct units. Both are required.
It is important to consider how to use significant figures when doing mathematical
operations. Using a calculator, which can report 8 digits, does not make your result more
accurate. You must report your calculated result to the correct number of significant figures
allowed by the laboratory measurements and not the calculator.
If the mathematical operation is addition or subtraction, your result can only be reported
to the decimal place of the least accurate measurement. The following examples may clarify this.
If you add 123.4 g to 0.123 g, the result is 123.5 g. If you add 1.2 g to 0.123 g, the result is 1.3 g.
If you subtract 1.234 g from 1.236 g, the result is 0.002 g. Note that in addition and especially
subtraction, you can appear to lose significant figures. So, in such cases, if one measurement can
only be made to the first decimal place, it is a waste of time to make the other measurement
carefully to the third decimal place.
If the mathematical operation involves multiplication and division, the result will have
the number of significant figures equal to that of the least significant piece of data. If you
multiply 123 by 12, the result is 1500 which has 2 significant figures and 2 zeros to place the
decimal point. Such results are better written in scientific notation (1.5  103) to avoid confusion.
Be sure you fully understand the meaning and use of significant figures as a major part of
your laboratory grade will be based on your lab measurements and data manipulation in your lab
reports.
© 2010 Anderson, Shine, Carberry, and Carreon
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APPENDIX E: PERCENT YIELD CALCULATION METHOD
The calculation of a percent yield is a very important part of those labs where a
chemical synthesis has been done. In your report be sure to correctly do the percent yield
calculation (showing the correct significant figures and units) and present it in a very clear
manner. Do not forget the show the correct units with each measurement as you perform the
calculation. A percent yield calculation is an application of a weight-weight problem, which you
learned in Fundamentals of Chemistry.
You must show how the calculations are done in an area that is separated from text. Do
not put data details in paragraph text. Present data details in tabular form and be sure this data is
near the text that makes reference to it for clarity of presentation or, if the calculations have been
attached to the end of your report as an appendix, give a clear sentence that refers the reader to
this page. Calculations should be close to where the final data are presented in your report.
Briefly, a percent yield calculation is an application of a weight-weight problem in General
Chemistry. You calculate the number of moles (or millimoles) of each reagent. Determine which
reagent is the limiting reagent from the balanced equation. Catalysts are not usually limiting
reagents. Then, determine from the balanced equation the maximum number of moles of the
desired product that could be obtained and this is your theoretical yield in moles. Convert this
number of moles of product to a theoretical weight of product. Then, divide the weight of
product that you obtained by the theoretical weight of product you calculated and multiply by
100%. Alternatively, you could determine the actual moles of product obtained by taking the
mass of the product isolated and dividing by its molecular weight. The percent yield in that case
would be the actual moles divided by the theoretical moles times 100%. Be sure to identify
which method you use by showing numerical and unit values for all data in your calculations.
Percent yield calculations will be a major part of your report grade in those labs where percent
yield data needs to be reported.
SAMPLE CALCULATION:
Below is just a guide to show you how the calculations are done, presented in a manner
to help you understand the process. This is not an acceptable percent yield calculation for your
lab report. The method below was adapted from a reaction of a diamine with an acid to give a
salt, which appeared in the Organic Chemistry I laboratory manual.
The balanced equation showed that 1 mole of diamine reacts with 1 mole of acid to give 1 mole
of salt.
You started with 1.20 mL of diamine. 1.20 mL  .951 g/mL gives 1.14 g of diamine
1.14 g of diamine/114 g/mole of diamine gives 0.0100 mole of diamine used.
You also weighed some tartaric acid that varied from group to group. Say your group weighed
0.732 g.
The number of moles of acid in the 0.732 g is 0.732 g/ 150 g/mole of tartaric acid or 0.00488
mole of tartaric acid.
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From the balanced equation, the acid is the limiting reagent and the theoretical yield of the
product would be 0.00488 moles of salt.
From the molecular weight of the product, the theoretical weight of the product is 0.00488 mole
 264 g/mole of salt or 1.29 g.
If you obtained .847 g of product, your percent yield is
(0.847 g /1.29 g)  100% or 65.7 %.
© 2010 Anderson, Shine, Carberry, and Carreon
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APPENDIX F: GREEN METRICS
For most of this laboratory course, percent yield was used to measure the efficiency of
a synthetic reaction. However, the percent yield does not consider the fate of other reagents,
solvents or catalysts. It does not consider the costs involved in handling byproducts and
hazardous waste. As we have seen, green chemistry focuses on finding methods for the
development of new, less polluting processes. Green metrics is a branch of green chemistry,
which attempts to quantify the total environmental cost of a process. Green metric calculations
keep track of the amount of material that goes into and comes out of a chemical reaction.
Common green metric terms include: percent yield, E-factor, atom economy, atom efficiency,
effective mass yield and reaction mass efficiency. Each of these terms will be described below.
The percent yield has been used throughout this course to give a crude measure of the
success of a synthetic reaction. It is:
(actual yield  theoretical yield)  100%
Percent yield could be increased by using better processes or reaction conditions, minimizing
competing reactions, and minimizing mechanical loss.
The E-factor (efficiency factor) is a number that correlates with the amount of organic
and aqueous waste produced in a chemical process. It is:
total waste in g/product weight in g
The smaller the E-factor, the better the process since less waste is produced. The E-factor has a
range of 0 to infinity.
Atom economy (or percent atom economy) is a theoretical number that shows the
amount of reactants that remain in the final product. It is:
(MW of product/sum of MW of all reactants)  100%
The bigger the number for atom economy, the higher the percent of all reactants that remain in
the final product. The range is 0% to 100%. Atom economy is dictated by the chemical reaction.
The Diels-Alder reaction is an example of a reaction that has a good atom economy.
Atom efficiency is a practical number that attempts to join the concept of percent yield
and atom economy. This metric gives a good indication of the greenness on the process. Atom
efficiency is:
Percent yield  atom economy
Atom efficiency has a range of 0% to 100% and the closer the atom efficiency is to 100%, the
greener the process.
Effective mass yield is the percentage of the mass of the desired product relative to the
mass of all hazardous materials used in the synthesis. It is:
(product mass g/hazardous reagents mass g)  100%
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This metric evaluates the amount of hazardous reagents used in making the final product. It may
be difficult in determining what is hazardous or not.
Reaction mass efficiency is the percentage of the mass of reagents that remain in the
final desired product. It takes into account the stoichiometry, yield, and atom economy. It is:
(product mass in g/mass of reagents in g)  100%
The larger the number for reaction mass efficiency, the better the process. The range is 0% to
100%. Reaction mass efficiency is similar to effective mass yield. The only difference is that the
effective mass yield takes into consideration the hazardous reagents whereas the reaction mass
efficiency uses the total mass of all reagents.
It would be a worthwhile exercise for the student to apply the above principles to an
evaluation of the greenness of the hydrolysis of methyl benzoate experiment or, indeed, any
other experiment performed this semester.
© 2010 Anderson, Shine, Carberry, and Carreon
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APPENDIX G: CHEMICAL DATA
INTRODUCTION:
This appendix will present physical data and safety data about chemical substances that
are mentioned in the experiments described in this manual. The data are presented in an Excel
spreadsheet format. Table 1 gives all the data in one location but the printing is small and may be
difficult to read. Table 2 gives safety information while Table 3 gives the physical properties of
the chemicals. Data were obtained from chemical handbooks, supplier catalogs, and material
safety data sheets. In many cases, the value for a given piece of data such as a melting point
varied from source to source within a narrow range. Therefore, you may find a data value from
some source you check that does not agree with what is reported in this appendix. However, if
you find any serious error in the data tables, please send an e-mail to Robert Shine
(bshine@ramapo.edu) informing him of the nature of the error. A blank cell in the data tables
indicate the value for that data point was not found or does not apply. For example, the boiling
point of an inorganic solid is generally not useful in this course. Also, the density for a solid
substance could be meaningless for us.
Remember that you can obtain more complete information from the Material Safety
Data Sheet (MSDS) for a given substance. You can obtain a material safety data sheet for a
compound by doing a Google search. For example, an MSDS for acetone can be obtained by
typing "acetone MSDS" (don't include the quote marks) in the search box. Usually this search
will result in many hits so you can just link to one of the sources. If you do not get any results
from a Google search, try to search using an alternate name for the chemical. With practice, you
will find your favorite source for an MSDS.
EXPLANATION OF COLUMN HEADINGS:
The Chemical Name column gives the usual name for the substance listed. All tables
are arranged alphabetically according to the Chemical Name. The Alternate Name column gives
another name for a given substance. The Formula column gives the general chemical formula
for that substance. If you compute the molecular weight for that chemical formula, you would
obtain the data value in the Mol.Wt. column. The units for these data are grams/mole. The next
column, Melt.Pt., gives the melting point in degrees Centigrade (Celsius). After this, comes the
column Boil.Pt. which gives the boiling point for the substance in degrees Centigrade (Celsius).
The Density column gives the density for the substance is grams/mL. The density for a solid is
not useful in this course but the density for a liquid could give a useful method when measuring
liquid reagents. One can accurately measure a liquid by volume. The weight of that sample
would then be equal to the volume times the density. If you know the weight you wish to
measure, the volume would be equal to the desired weight divided by the density. Expressed in
mathematical terms, the formulae are:
Volume = Weight  Density
Weight = Volume  Density
The remaining three columns give some safety data. The CAS # is the Chemical
Abstract Service number for the substance. The CAS# is a unique identifier for a chemical
assigned by the American Chemical Society. The FlashPt gives the temperature at which a
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substance can be readily ignited. Substances with a flash point below 100 degrees Centigrade are
classified as flammable while those above 100 degrees are called combustible. Be especially
cautious with chemicals with a flash point below 0 degrees. The final column gives the NFPA
Rating of the substance. NFPA stands for the National Fire Protection Association and their web
site can be found at www.nfpa.org (not .com) which is a 'for profit' organization. You can find
more information about this rating system by doing a Google search on “nfpa diamond”. The
rating assigns values from 0 to 4 for each of three categories Health, Fire, and instability (which
is sometimes called reactive). A value of 0 indicates little or no hazard whereas a value of 4
indicates an extreme hazard.
© 2010 Anderson, Shine, Carberry, and Carreon
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