Organic Chemistry (ERT 102)
Laboratory Module
EXPERIMENT 1
Chlorophyll Extraction, Column and Thin Layer
Chromatography
1. OBJECTIVE :
1.1 To extract pigments from spinach leaves
1.2 To separate the pigments by column and thin layer chromatography
2. INTRODUCTION
Green leaves contain a variety of organic compounds. The compounds of longchain, conjugated absorb visible light and reflect the leaf green color. The leaf green
color consists of common pigments such as carotenes (α and β), lycopenes,
chlorophyll (a and b), cryptoxanthins (α and β), pheophytins (a and b) and
xanthophylls. The lycopenes are the non-cyclic analogues to the carotene; the
cryptoxanthins and xanthophylls are the derivatives of carotenes. The chlorophyll can
be converted to the pheophytin in certain conditions. The pheophytins are the same
as the cholorophyll, but without the central magnesium (Mg) atom. The cholorophyll
structure is as shown in Figure 1.
Figure 1: Chemical structure of cholorophyll
The chlorophyll is a large molecule, thus it has very low vapor pressure.
Because of this reason, purification methods, which depend upon volatility cannot be
used to separate it. Two effective methods to separate the chlorophyll from the
pigments are column and thin layer chromatography (TLC).
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Organic Chemistry (ERT 102)
Laboratory Module
3.
APPARATUS/CHEMICALS/MATERIAL:
3.1
Conical flasks
3.2
Beakers
3.3
Separatory funnel
3.4
Acetone
3.5
Hexane
3.6
Sodium chloride
3.7
Anhydrous sodium sulfate
4. PROCEDURES
4.1 Extraction of pigments
4.1.1 Cut 10-15 g of frozen spinach leaves into small pieces and place them in a
500ml beaker.
4.1.2 Add 25ml of acetone to the spinach and mix with a glass rod or spatula. Let
the mixture stand for at least 5 minutes in a fume hood.
4.1.3 Carefully decant the acetone extract into a 125ml separatory funnel. DO NOT
transfer the spinach leaves. Then use a 250 ml Erlenmeyer flask to press the spinach
leaves.
4.1.4 Add another 25ml acetone to the spinach leaves and mix as in step 4.1.2.
Repeat step 4.1.3. Discard the spinach leaves into a waste container.
4.1.5 Add 25ml of hexane to the separatory funnel and mix with venting. Record
your observations. Refer to Figure 1 below for stand and venting of the separatory
funnel.
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Organic Chemistry (ERT 102)
Laboratory Module
Figure 1: The separatory funnel in the ring stand (above), and steps for venting the
funnel (below).
4.1.6 Add 25ml of saturated sodium chloride to the separatory funnel and mix. Allow
the layers to separate. Collect the upper layer (organic) in a beaker and transfer the
bottom layer (aqueous) to another beaker. NOTE: Label the beakers.
4.1.7 Wash the aqueous layer with 25ml of hexane in a separatory funnel. Combine
the organic layer.
4.1.8 Extract the combined organic layers with 25ml of saturated sodium chloride.
Let the layers to separate and discard the bottom layer (aqueous).
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Organic Chemistry (ERT 102)
Laboratory Module
4.1.9 Dry the organic layer by passing it through a funnel containing 5±0.1g of
anhydrous sodium sulfate (use cotton and glass wool plug in the funnel to dry the
organic mixture).
4.1.10 Keep the dried organic mixture in a water bath for about 10-15 minutes (68
o
C) to concentrate the extract. The concentrated extract will be used for column and
thin layer chromatography analysis.
4.2 Column Chromatography
(Steps 4.2.1-4 are prepared by the lab technician)
4.2.1 The column used should have a 2cm O.D and be approximately 32cm in
length. The column must be clean and dry before using.
4.2.2 Place a small piece of cotton (pea size) into the column, (use a glass rod or
airline to get the cotton to the bottom of the column). Clamp the column to a ring
stand using a micro clamp. Add 0.4g of sand to the column.
4.2.3 Add 10g of alumina to the column and gently tap the column to settle the
alumina. NOTE: a small disposable pipet with the ends cut off can be used as a
funnel. Make sure each layer in the column is level before adding the next.
4.2.4 Add the dried sample to the column.
4.2.5 Finish packing the column by adding 0.6g of sand to the column. A sample of
how the column should look is illustrated in Figure 2.
Figure 2: Column set-up
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Organic Chemistry (ERT 102)
Laboratory Module
Running the column
4.2.6 Slowly add mobile phase of 95: 5 ethyl acetate: ethanol to the column (≈ 8ml).
4.2.7 The first fraction to elute from the column is yellow. The second fraction is
yellow-green (eluent between distintly color band). The last fraction is green. Collect
the last fraction. Save the fraction for TLC analysis.
4.3 Thin Layer Chromatography
4.3.1 Prepare aluminium plate.
4.3.2 Using a sharp pencil, draw a straight line horizontally across the plate and
about 10 mm height from below the plate. The plate is as shown in Figure 3b.
4.3.3 Make 2 spots of equivalent distance from each other on the straight line. The
plate will be spotted with 2 samples (i.e. 1. The initial pigments extract; 2. Green
fraction collected from the column chromatography)
4.3.4 Dip a capillary tube into the pigments extract.
4.3.5 On the aluminium plate, make a contact between the dipped capillary tube
and the exact first spot of each plate. The quantity of liquid inside the capillary tube
should be minimum.
4.3.6 Leave the spots to dry.
4.3.7 Repeat the dropwise addition for the second and third time.
4.3.8 Ensure that each drop size is minimized.
4.3.9 Using a new capillary tube, drop the green fraction from column
chromatography solution onto the second mark on the aluminium plate three times.
4.3.10 Repeat the procedures.
4.3.11 Prepare a solution of 70:30 ml Hexane: Acetone and place it in a TLC
development chamber (or beaker) of about 5mm deep. Set-up the chamber as
shown in Figure 3a.
4.3.12 Put one plate, with the spots below into the chamber containing the solvent
solution.
4.3.13 Put the lid on the beaker and allow the solvent travels until 0.5 cm from the
upper end of the plate.
4.3.14 Remove the plate and using a pencil, mark the front solvent.
4.3.15 Leave the plate to dry.
4.3.16 Calculate the Rf value for each spots of the plate.
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Organic Chemistry (ERT 102)
Laboratory Module
Figure 3a: TLC chamber
4
Figure 3b: TLC plate
RESULTS
Calculate the Rf values for each spots separated on the TLC plate
5
DISCUSSION & EVALUTION /EXERCISES:
5.1 During extraction of pigments when the acetone pigment mixture was mixed
with hexane and allowed to stand what happened?
5.2 If pure acetone and hexane are mixed (Hint: Mix them in a separatory funnel)
what should happen and why did not this occur in this experiment?
5.3 What does Rf stand for?
5.4 Why can a mixture of organic components be separated by thin layer
chromatography?
5.5 The versatility of column chromatography results from the many factors that can
be adjusted. Name three of them?
6
CONCLUSION
Based on the experimental procedure done and the results taken, draw some
conclusions to these experiments.
Safety precautions:
1. Make sure that you do not accidentally drop any samples solution on the plate.
2. Wear gloves when handling the finished plates.
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Organic Chemistry (ERT 102)
Laboratory Module
EXPERIMENT 2
Fractional Distillation of Diethyl Ether and 1,2-Dimethoxy
Ethane
1. OBJECTIVE:
1.1 To fractionally distill a mixture of ethyl ether and 1,2-dimethoxy-ethane
1.2 To fractionally distill the mixture using three types of column packing material
1.3 To collect the fractions and plot a distillation curve
1.4 To compare the effect of the packing materials on the distillate
INTRODUCTION
Fractional distillation is separation of a mixture of two or more liquids that present in
noticeable amounts into several fractions. Basically, the fractional distillation is a
systematic way to redistilate the distillates (fractions of increasing purity). Figure 1
and 2 illustrate the distillation curves on how the two liquids separate. Figure 1 below
shows an ideal distillation curve.
Figure 1: Ideal separation distillation curve
3.
APPARATUS/CHEMICALS/MATERIALS:
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Organic Chemistry (ERT 102)
Laboratory Module
3.1 ethyl ether
3.2 1,2-dimethoxy-ethane
3.3 Packing materials:
i. Copper ribbon
ii. 6mm glass beads
iii. Raschig rings
3.4 Fractional distillation apparatus set
3.5 10 ml measuring cylinder
3.6 5 ml screw cap vials
3.7 Boiling stones
4. PROCEDURE:
4.1
Set-up the fractional distillation apparatus (Figure 3) using one of the packing
materials listed above. The teaching engineer/ technician will indicate which packing
material to use.
Figure 3: Fractional distillation set-up
4.2
Place 60ml of 1:1 Ethyl ether: 1,2-dimethoxy ethane into the distilling flask
(round bottom flask). Add 2-3 boling stones to the flask.
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Organic Chemistry (ERT 102)
Laboratory Module
4.3
Distill the mixture by heating the heating mantle at rate of distillate production
of 1-2 drop per second
4.4
Record the temperature for every 1-2ml of distillate collected. If the
temperature begins to drop, increase the the power of the heating mantle.
4.5
Collect ten 5ml fractions using a 10ml measuring cylinder. Keep the fractions
in screw cap vials.
4.6
After finish collected the tenth fraction, remove the heating mantle and let the
apparatus cool.
4.7
Send your raw data of temperature and distillate volume to the teaching
engineer.
5. RESULTS
Plot the distillation curve of temperature versus distillate volume for each type of
packing material.
6. DISCUSSION & EVALUTION /EXERCISES
6.1
At what volume of distillate collected, during fractional distillation, would a
rapid increase in temperature be expected for 1000ml of a 1;1 mixture of and ideal
solution?
6.2
Which packing material provided the most ideal separation?
6.3
How might the separation of ethyl ether and 1,2-dimethox ethane be improved
using one of the packing materials used in this experiment
7. CONCLUSION
EXPERIMENT 3
Separation of Benzoic Acid and Biphenyl
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Organic Chemistry (ERT 102)
Laboratory Module
1. OBJECTIVE
1.1 To separate a mixture of benzoic acid and biphenyl by extraction
1.2 To recover the separated compounds
1.3 To calculate the recovery percentage
2. INTRODUCTION
Organic solution of benzoic acid and biphenyl can be separated by liquid-liquid
extraction. Benzoic acid is an organic acid with carboxylic acid functional group (COOH). Biphenyl is a typical organic hydrocarbon and is neither acidic nor basic.
The more polar benzoic acid molecules will be extracted to an aqueous basic
solvent, while the biphenyl will be moved into organic layer.
The benzoic acid is recovered by acidifying the aqueous solution, which causes the
benzoic acid to precipitate, whereupon it is isolated by filtration. The biphenyl is
isolated by drying the aqueous solution to remove dissolved water, and finally
distillation of the solvent – the biphenyl will remain as a non-volatile residue. The
whole operation is accomplished simply in a short period of time using these
principles of extraction. The three components are isolated in nearly pure form; minor
contaminants could be removed, if desired, by recrystallization (Experiment 4).
3. APPARATUS/CHEMICALS/MATERIALS
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
Benzoic acid
Biphenyl
Separatory funnel
Ethyl ether
Beaker
Erlenmeyer flask
Anhydrous sodium sulfate
Round bottom flask
Rotary evaporator
Hydrocloric acid
4. PROCEDURE:
Extraction of benzoic acid and biphenyl mixture
4.1 Place 2.5±0.01g of benzoic acid and 2.5±g biphenyl into a 125ml separatory
funnel. Record the exact weight of the compounds to the nearest 0.01g.
4.2 Dissolve the benzoic acid and biphenyl mixture in 50ml ethyl ether.
4.3 Extract the mixture with five 25ml portions of 5% sodium bicarbonate
4.4 Combine the aqueous layer (sodium bicarbonate extractions) in a 400ml beaker.
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Organic Chemistry (ERT 102)
Laboratory Module
4.5 Place the organic (ether) layer in a 125ml Erlenmeyer flask
Biphenyl recovery
4.6 Add 1-2g of anhydrous sodium sulfate to the ether biphenyl mixture. Swirl the
flask to thoroughly mix the contents.
4.7 Let the sodium sulfate settle and the decant the solution mixture into a preweighed 100ml round bottom flask
4.8 Remove the ether in the solution using a rotary evaporator. Weight the flask and
record the weight of biphenyl recovery. Calculate the percent recovery.
4.9 Keep the recovered biphenyl for a next experiment (Experiment 4).
Benzoic acid recovery
4.10 Cool the beaker containing aqueous extracts in an ice bath for at least five
minutes.
4.11 Add 6M HCL in 1-2ml portions until no more precipitate forms in the aqueous
extracts.
4.12 Collect the crystal by vacuum filteration and dry the crystal in the funnel for at
least ten minutes.
4.13 Determine the weight of benzoic acid recovered and calculate the recovery
percentage.
4.14
Keep the recovered benzoic acid for the next experiment (Experiment 4).
4. RESULTS
i. Biphenyl recovery
Mass of flask:
Mass of flask with recovered biphenyl:
Mass of recovered biphenyl:
Percentage yield of recovered biphenyl:
ii. Benzoic acid recovery
Mass of flask:
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Organic Chemistry (ERT 102)
Laboratory Module
Mass of flask with recovered benzoic acid:
Mass of recovered benzoic acid
Percentage yield of recovered benzoic acid:
Calculation of % of recovery:
% Re cov ery 
mass of recovered substance (g)
 100
mass of crude substance (g)
5. DISCUSSION & EVALUTION /EXERCISES
5.1
Define extraction?
5.2
How can the organic layer be determined during extraction?
5.3
What are four common signs that indicate an organic solution is dry?
5.4
Write the equation for the reaction of sodium bicarbonate with benzoic acid.
5.5
Why is the beaker containing the bicarbonate extracts cooled before adding
HCl?
6. CONCLUSION
EXPERIMENT 4
Crystallization of Benzoic Acid and Biphenyl
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Organic Chemistry (ERT 102)
Laboratory Module
1.
OBJECTIVES
1.1
To crystallize the recovered benzoic acid using water
1.2
To crystallize the recovered biphenyl using appropriate solvent
2.
INTRODUCTION
Crystallization is a method to purify a solid. The process requires a suitable solvent.
A suitable solvent is one which readily dissolves the solid (solute) when the solvent is
hot but not when it is cold. The best solvent exhibits a large difference in solubility
over a reasonable range of temperatures. (e.g, Water can be a crystallization solvent
between 0-100 oC; hydrocarbon solvents such as hexanes or petroleum ether have a
different temperature range since they can be cooled below 0 oC but boil below 100
o
C).
During crystallization, a crude solid is boiled with appropriate solvent until the solid is
completely dissolved. If the saturated hot solution is allowed to cool, solute is no
longer soluble in the solvent and forms crystals of pure compound. Impurities are
excluded from the growing crystals and the pure solid crystals can be separated from
the dissolved impurities by filtration.
3.
PROCEDURES
Crystallization of Benzoic acid
3.1 Determine the melting of the crude benzoic acid (sample from Experiment 3)
3.2 Weight 2 ± 0.01g (record the exact weight) of benzoic acid and transfer it into a
250ml Erlenmayer flask.
3.3 Add 40ml of distilled water to the flask.
3.4 Heat the mixture on a hot plate up to the boiling point while stirring the mixture.
Boil until the benzoic acid completely dissolved.
3.5 Remove the flask from the hot plate. If undissolved benzoic acid particles still
appear in the mixture, add an additional small amount of distilled water (several
drops at a time from a Pasteur pipette) and continue boiling the solution.
(NOTE: Adding too much volume of distilled water will cause the solution not be
saturated thus reducing the yield of purified benzoic acid).
3.6 Determine the melting point of the crystallized benzoic acid.
3.7 Calculate the percent recovery of the pure benzoic acid.
Crystallization of biphenyl
3.8 Determine the melting point of the crude biphenyl (sample from Experiment 3).
3.9 Set-up a reflux apparatus using 50ml round bottom flask as shown in Figure 1.
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Organic Chemistry (ERT 102)
Laboratory Module
3.10 Place 2 ± 0.01g (record the exact weight) of crude biphenyl in the flask and
attach the condenser.
3.11 Start circulating the water through the condenser.
3.12 Add enough solvent to just cover the biphenyl in the flask through the top of
the condenser using a disposable pipette.
3.13 Heat the flask using a heating mantle until all the biphenyl dissolves or the
solvent begins to boil.
3.14 If the solvent begins to boil before the biphenyl completely dissolved adds
more solvent dropwise until all the biphenyl completely dissolved (continue heating).
If the solvent begins to boil too rapidly remove the heating mantle and let the flask
cool.
3.15 Once experiment finished, let it cool for several minutes before turning off the
cooling water. Then, remove the condenser.
3.16 If the biphenyl crystal does not appear after the cooling process, induce the
crystallization process. To induce the process, scrape the sides of the flask above
the level of the solution. This may dislodge some undetectable, small crystals that will
drop into the solution and “seed” the solution. A seed solution may help to induce
crystallization.
3.17 Collect the solid using a vacuum filteration. Hands dry the solid using clean
paper towel, let them dry completely.
3.18 Weight the solid and calculate the percentage of biphenyl recovery through the
crystallization process.
3.19 Determine the melting point of your crystallized biphenyl.
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Organic Chemistry (ERT 102)
Laboratory Module
Figure 1: Apparatus set-up for reflux
4. RESULTS
Substance
Benzoic acid
Mass of impure substance
(From Experiment 3)
Mass of crystallized
substance + weighing
paper
Mass of weighing paper
Mass of crystallized
substance
Calculation percentage of
substance recovery
Melting point of
crystallized substance
Calculation of % of recovery:
% Re cov ery 
5.
mass of crystallised substance (g)
 100
mass of substance before crystallisation (g)
DISCUSSION & EVALUTION /EXERCISES:
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Biphenyl
Organic Chemistry (ERT 102)
Laboratory Module
5.1 When a solid compound is contaminated what happens to its melting point?
5.2 What is a main characteristic of a good solvent used in crystallization?
5.3 Why may be the use of a reflux apparatus be preferred for performing a
crystallization?
5.4 After crystallization, why are the crystals washed with cold solvent?
6.
CONCLUSION
EXPERIMENT 5
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Organic Chemistry (ERT 102)
Laboratory Module
Synthesis, Purification and Quantification of Ester
1. OBJECTIVE
1.1 To synthesize ester from carboxylic acid and alcohol reaction
1.2 To purify ester through distillation
1.3 To quantify ester using Gas Chromatography
2. INTRODUCTION
Esters are naturally abundant and readily synthesized, but all have the same
following structure.
O
R - C -O -R'
Every day fragrances, such as the “rich smell’ of fresh ground coffee, are a
combination of esters (>200 identifiable esters found so far in coffee!). However,
some esters are readily recognized by their very characteristic flavor or odor.
In the Table 1 below, several examples of esterification products are given.
Table 1: Combinations of carboxylic acids and alcohols resulting in esters
Ester
Structure
Fragrance Carboxylic
Alcohol
acid
Iso-butyl
HCO2CH2CH(CH3)2
Raspberry Formic acid
Isoformate
essence
butanol
Propyhl
CH3CO2CH2CH2CH3
Pear
Acetic acid 1-propanol
acetate
essence
Octyl
CH3CO2CH2(CH2)6CH3
Orange
Acetic acid
octanol
acetate
essence
Ethyl
CH3CH2CH2CO2CH2CH3 Pineapple
Butyric acid
ethanol
butyrate
essence
Methyl
CH3CH2CH2CO2CH3
“Apple like” Butyric acid methanol
butyrate
essence
In esterification reaction, esters can be prepared by reversible, acid-catalyzed,
combination of a carboxylic acid with an alcohol. Because it is reversible, the reaction
must be shifted to the product side by using excess reagent, or removing one of the
products. This reaction is also limited by any steric hindrance in the carboxylic acid or
the alcohol. The general equation for an esterification is shown below.
O
+
R - C - OH
H+
R'
O
+ H3O+
O
R - C -O -R'
H
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Organic Chemistry (ERT 102)
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3. EQUIPMENT / APPARATUS
3.1
Distillation apparatus
3.2
Isoamyl Alcohol
3.3
Acetic acid
3.4
parafilm
3.5
distilled water
3.6
methylene chloride
3.7
Erlenmeyer flask
3.8
Stopper
3.9
Rotary evaporator
3.6
10% Na2CO3
3.7
Sodium sulphate Na2SO4
4.
PROCEDURES
4.1
Part A – Synthesis of the ester
4.1.1 Mix 100ml of 0.05 moles of isoamyl alcohol and 250ml of 0.125 moles of
acetic acid in an Erlenmeyer flask
4.1.2 Add 1ml of concentrated sulfuric acid and gently swirl the flask to mix the
contents.
4.1.3 Stopper the flask and wrap with parafilm.
4.1.4
Let the reaction occurs for 40 minutes.
O
R - C - OH
+
H+
R'
O
+ H3O+
O
R - C -O -R'
H
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Organic Chemistry (ERT 102)
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4.2 Part B – Purification of the ester
4.2.1 Pour contents of the reaction flask into the separatory funnel.
4.2.2 Rinse the flask with both 12 mL of methylene chloride and 10 mL of water and
add these rinses to the separatory funnel also.
4.2.3 Shake, then separate the aqueous and organic layer: if two layers are not
visible, add 10 mL of water to the separatory funnel. Differentiate the aqueous and
organic layer.
4.2.4 Re-extract the aqueous layer with another 12 mL of methylene chloride.
Combine the organic layers and wash them twice with 8 mL of 10% Na2CO3.
4.2.5 Dry the organic layer over anhydrous sodium sulfate.
4.2.6 Swirl the mixture from time to time over 10 minute-period. Then allow the
sodium sulfate to settle and transfer the organic layer into a clean and dry container.
4.2.7 Place your sample in a 100 mL round bottom flask. Your teaching engineer
will show you how to use the rotary evaporator.
4.2.8 After removal of the methylene chloride, place your sample in a 50 mL round
bottom flask. Record the boiling point of the ester. Collect it in a clean container.
4.2.9 Run a GC to determine its purity with a help of your teaching engineer.
*Safety precautions
*H2SO4 is very corrosive; if it comes in contact with your skin, flush immediately with
large amounts of water. Although
*Less corrosive than H2SO4, acetic acid is also corrosive and should be rinsed
immediately off the skin.
*Chemical like methylene chloride is mild irritants and/or poisonous if ingested in
large amounts and skin contact and inhalation of vapors should be avoided.
*Several reagents used are flammable; do not use flames in this lab. Wear gloves
and protective clothing.
*Isoamyl alcohol is an irritant. Avoid breathing vapors.
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Organic Chemistry (ERT 102)
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5. RESULTS
5.1 The boiling point of ester:
6. QUESTIONS
6.1 Write the chemical reaction between the reactants in the experiment. Find the
equilibrium constant.
6.2 What is the name of the ester produced? Find the application.
6.3 Why did you wash your product with methylene chloride? What was the purpose
of washing with water?
6.4 Explain the function of the acid catalyst in a Fisher Esterification reaction.
6.5 Determine the yield of the ester.
7. DISCUSSION
Discuss the results you gained from the gas chromatography.
8. CONCLUSION
Based on data and discussion, make your overall conclusion by referring to the
experimental objective.
EXPERIMENT 6
Synthesis of Polyamide- Nylon 6, 10
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Organic Chemistry (ERT 102)
Laboratory Module
1. OBJECTIVE
1.1 To synthesize nylon 6, 10 from hexamethylenediamine
1.2 To calculate weight of the nylon synthesized
2. INTRODUCTION
A linear polyamide is formed through a condensation reaction between a dicarboxylic
acid and a diamine. Nylon 6, 6 is the commercial nylon which produces from adipic
acid and hexamethylenediamine. The polyamide, nylon 6, 6 shows that its monomer
of has six carbons. There is another way to produce nylon 6,6, it can be made by
using the acid chloride of adipic acid (adipoyl chloride)
This experiment is conducted to synthesize a polyamide, nylon 6, 10. In order to
produce nylon 6,10, the amine molecule must have a –NH2 group at each end, and
the acid chloride must have a –COCl group at each end. The diamine and the diacid
chloride bond together, end-on-end, to form very long chains. Nylon 6, 10 is
synthesized from the acid chloride of sebacic acid (sebacoyl chloride) and
hexamethylenediamine. The sebacoyl chloride dissolved in cyclohexane, which
carefully added to hexamethylenediamine dissolved in water. As a result, two layers
are formed. The polymer then be drawn out to develop a continous strand of nylon.
Figure 1 below shows the reaction of nylon 6, 10 formation.
Figure 1: Formation of nylon 6, 10 from hexamethylene diamine and sebacoyl
chloride
3.
EQUIPMENT / APPARATUS
3.1
Sebacoyl chloride
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Organic Chemistry (ERT 102)
3.2
Hexamethylene diamine
3.3
Cyclohexane
3.4
Sodium hydroxide
3.5
Aluminium or copper wire
3.6
Beakers
4.
PROCEDURES
Laboratory Module
4.1 Pour 10ml of 5% aqueous hexamethylenediamine into a 50ml beaker
4.2 Add 10 drops of 20% sodium hydroxide
4.3 Carefully add 10ml of 5% sebacoyl chloride in cyclohexane to the beaker.
4.4 Draw out the nylon that is formed at the interface of the two solutions slowly,
using alluminium of cooper ware as a hook.
4.5 P,ace the nylon strand on a piece of paper towel and press it to dry (use the
bench top hood).
4.6 Mix the contents of the beaker vigorously using the wire hook. Decant the liquid
into a proper waste container. Wash the remaining nylon in the beaker with water
and let it dry.
4.7 Determine the weight of the synthesized nylon 6, 10.
5.
5.1
RESULTS
Calculate the yield of the nylon 6, 10 in this experiment.
(Hint: To calculate the yield, cancel out the n’s from the formation equation (Figure
1)).
6. DISCUSSION
Discuss the results you gained from the gas chromatography.
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Organic Chemistry (ERT 102)
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7. CONCLUSION
Based on data and discussion, make your overall conclusion by referring to the
experimental objective.
EXPERIMENT 7
Synthesis of Acetaminophen (Paracetamol)
1.
OBJECTIVES
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Organic Chemistry (ERT 102)
Laboratory Module
1.1 To synthesize paracetamol from p-aminophenol and acetic anhydride
1.2 To calculate the yield of the synthesized paracetamol
1.3 To determine the boiling point of the paracetamol
2.
INTRODUCTION
Paracetamol is a very widely used medicine. It is a mild painkiller and reduces the
temperature of patients with fever. These actions are known respectively as
analgesic and antipyretic.
Synthesis of paracetamol involves three steps from phenol. The first step is nitration
of phenol to form 4-nitrophenol and 2- nitrophenol. Then, the second step is
reduction of nitro group to amine. The last step is formation of amide, which produce
paracetamol. Starting material for any synthesis should be such that it is easily
available. Phenol though easily available, was not used as a starting material
because of the difficulty of separation of the isomers after nitration and the
subsequent reduction. So 4-aminophenol was used as the starting point. Thus, in this
experiment, the synthesis of paracetamol starts from p-amoniphenol. The chemical
reaction of the synthesis is as shown below:
3.
GLASSWARES/CHEMICALS
3.1 4-aminophenol
3.2 Acetic anhydride
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Organic Chemistry (ERT 102)
Laboratory Module
3.3 Pure paracetamol
3.4 Heating mantle
3.5 Round bottom flask 50 ml
3.6 Buchner funnel
3.7 Elenmeyer flask
3.8 Beaker 100ml
3.9 Glass rod
4.0 Petri dish
4.
PROCEDURES
4.1 Place 5.5g of p-aminophenol in a 50ml round bottom flask.
4.2 Add 15ml of distilled water to the p-aminophenol in the round bottom flask.
4.3 Drop 6ml of acetic anhydride carefully in the mixture of p-aminophenol and
distilled water.
4.4 Set up the reflux apparatus
4.5 Reflux the mixture for 20 minutes.
4.6 After all the substrate dissolved, let the solution cool down.
4.7 Filter the crystal that appear in the flask on the Butcher funnel
4.8 Wash the crystal with cold water until the filtrate change to pH 7
4.9 Add 20ml distilled water to the synthesized crude paracetamol and reflux again
to recrystallize it. (Detail recrystallization methods can be referred to the previous
experiment).
4.10 Pour the hot solution into small beaker and cool down in ice water bath.
4.11 Filter the product and hand dry using paper towel
4.12 Determine the mass of the paracetamol.
4.13 Calculate the yield and determine the melting point of the synthesized
paracetamol.
5.
RESULTS
6.
DISSCUSSION/EXERCISES
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Organic Chemistry (ERT 102)
7.
Laboratory Module
CONCLUSION
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