Separation and Purification of Two Unknown Liquids by Simple Distillation and
Two Unknown Solids by Acid-Base Extraction and Recrystallization and
Identification by Mass Spectrometry, Infrared Spectroscopy, and Nuclear Magnetic
Resonance
Audrey Lullo
CHE 231L Section 801.
Department of Chemistry, DePaul University,
1110 W. Belden Avenue, Chicago, IL 60614.
Annym2693@aol.com.
19 March 2014.
ABSTRACT:
The separation, isolation, purification and identification of two unknown liquids
and two unknown solids is performed through simple distillation, liquid-liquid extraction,
mass spectrometry, infrared spectroscopy, and both proton and carbon nuclear magnetic
resonance respectively. Simple distillation is used to separate and purify a mixture of
two miscible liquids. To separate two unknown solids the process of liquid-liquid
extraction is used. The separate and pure liquids and solids were determined to be:
acetonitrile for the low boiling liquid unknown #8, 1-butanol for the high boiling liquid
unknown #8, 3-bromo benzoic acid for the carboxylic acid solid unknown #20, and
benzophenone for the neutral solid unknown #20.
INTRODUCTION:
There are many ways in which to separate, isolate and purify compounds
depending on whether or not these compounds are liquids or solids. One way in which to
separate and purify two miscible liquids is simple distillation. Simple distillation only
works to separate two liquids that are completely miscible with each other and that boil
under 150°C. Not only must both liquids boil under a certain temperature, they must also
boil at temperatures that are different by at least 25°C in order to achieve complete
separation.1 Simple distillation also works to purify a liquid because impurities will boil
off at different temperatures than that of the pure sample. When working with an impure
sample of acetone, simple distillation would separate the pure acetone from the impurities
because the impurities have very low vapor pressures making condensation and vapor
nearly impossible. Therefore, the pure acetone will separate from the impurities resulting
in a pure sample. The theory of distillation is essentially that, vapor pressure and
temperature have a direct relationship. While one increases so does the other. This is
exemplified in the Clausius-Clapeyron equation:
𝑝 = 𝑝°𝑒𝑥𝑝 [
−𝛥𝐻 1 1
( − )]
𝑅 𝑇 𝑇°
In this equation p° and T° are both known vapor pressure and temperature respectively,
ΔH is the heat of vaporization, R is the gas constant, T is the ideal temperature, and p is
calculated.2 This equation shows the relationship between vapor pressure and
temperature. Because these liquids have been separated and purified, they can be
characterized by physical properties such as boiling point and density.
Simple distillation is not only useful in lab, but also is widely prevalent in the
food industry. For example, distillation is used in the processing of pectin, hop extract,
egg lecithin, and decaf coffee beans.3 Simple distillation is also used in the petroleum oil
industry to refine crude oil into a usable form for homes, cars, and airplanes (gasoline,
kerosene, and diesel fuel). These different types of fuel are categorized and separated
into solutions with similar boiling points by the distillation process.4 Therefore,
distillation can be used whenever there is a need to separate and purify a mixture of two
miscible liquids.
Unlike for liquids, two separate techniques must be used to separate and purify an
unknown solid. One technique of separation is extraction. For extraction to work, the
solid must be dissolved in a solvent that is not miscible with another solvent. Because
these solvents are immiscible, two separate layers form and can therefore be separated
from one another. The other extraction method, acid extraction, is useful in separating
contaminants such as heavy metal from the soil.5 Therefore, extraction is a useful tool
applicable to not only lab but also in the larger environment to separate a solid mixture
with two immiscible liquids.
To purify this solid that was just separated by liquid-liquid extraction, a process
called recrystallization is utilized. In order to recrystallize a solid, the solvent it is
dissolved in must be able to dissolve the solid while hot but not while cold, and keep
impurities dissolved at both temperatures.2 After, the solids are dissolved in the hot
solvents and precipitated back out of solution, the solids will be pure because the
impurities stay dissolved no matter what the temperature of solvent. Separating and
purifying an unknown solid is an important step in determining the identity of the
compound because then the pure sample can be characterized by melting point.
In order to accurately determine the structure and identify the solid and liquid
unknowns, a combination of mass spectrometry (MS), infrared spectroscopy (IR), and
carbon nuclear magnetic resonance (13C NMR) and proton nuclear magnetic resonance
(1H NMR) was used. Mass spectrometry is used to determine the molecular weight of a
compound. Knowing the molecular weight is crucial in determining possible molecular
formulas. The accuracy of various formulas is compared to a calculated index of
hydrogen deficiency (IHD), which is used to determine if pi bonds or rings are present,
and to what degree. The mass spectrometer works by fragmenting a compound into
cations by passing it through a beam of electrons in a vacuum. These fragments appear
as different sized peaks graphed based on a mass to charge scale. Therefore, the peak
farthest down the spectrum is the molecular ion peak, it expresses the molecular weight
of the compound and is denoted (M+). The tallest peak on the spectrum is known as the
base peak. Combining all of this information, a relatively accurate molecular formula for
a compound can be determined, which is an important step in identifying an unknown.6
Mass spectrometry has practical uses outside of lab. For example, it is used to efficiently
test for pesticides and toxins in food. Mass spectrometry can help to identify multiple
pesticides at once, therefore, making food healthier and safer.7
Another technique used to determine the identity of a compound is infrared
spectroscopy (IR). IR is used to determine possible functional groups in a compound.8 It
is possible to determine the functional groups because the functional groups are made of
covalent bonds that are depicted like a spring with balls attached to it. This model allows
the photons and radiation essential to infrared spectroscopy to excite the atoms until they
vibrate. Each atom vibrates at a specific frequency and this frequency is plotted on the IR
spectrum. Infrared spectroscopy is not only used in lab to determine the functional
groups and types of bonds a compound contains, but it is also a promising technique used
in the forensic sciences. Forensic scientists use IR to analyze various inks to determine
the presence of forgery and also sweatprints, which have become as valuable as the
fingerprint.9
Nuclear magnetic resonance is the final technique necessary to determine the
actual structure of a compound. It combines the molecular formula determined from the
MS and the functional groups determined from the IR and plots unique hydrogens and
carbons on the 1H NMR and 13C NMR respectively. These hydrogens and carbons are
considered unique based off of the environments they are in (i.e. bonds, relation to
electronegative elements, and the number of atoms they are bonded to). NMR takes
advantage of the natural spin individual nuclei have.10 The differences between the
magnetic spin and relative magnetic moment each nuclei experiences is the peak seen on
the NMR spectra.11 NMR is particularly helpful in the process of making and analyzing
drugs to determine the compounds attached to certain enzymes and proteins.12
RESULTS:
The results from the acid-base extraction and recrystallization of unknown solid
#20 are depicted in Table 1. Upon separation, the aqueous phase formed a powdery,
white carboxylic acid solid. After recrystallization, this solid was light and featherlike.
The organic phase formed an off-white crystalline solid. After recrystallization this
neutral organic solid was no longer off-white, but instead, white and powdery. The
percent recovery for the crude carboxylic acid solid was 39.31% and the percent recovery
for the crude neutral organic solid was 45.42%. After purification, the percent recoveries
for the carboxylic acid solid and neutral organic solid were 32.26% and 35.81%
respectively. The melting points were then determined for the pure carboxylic acid solid
and the pure neutral organic solid in order to characterize unknown # 20. The melting
point for the pure carboxylic acid solid was 158.3-160.3°C. The melting point for the
pure neutral organic solid was 38.6-42.5°C.
Table 1: Results from the Acid-Base Extraction and Purification of Unknown Solid # 20
Unknown Mixture #20
Carboxylic Acid Solid
Neutral Organic Solid
(RCO2H)
(RZ)
Physical Composition
Powdery, White, Solid
Crystallized, Off-White,
Solid
Mass of Original Mixture
5.0017
(g)
Mass of Crude Product (g)
1.9663
2.717
Mass of Purified Product
1.6135
1.7913
(g)
Percent Recovery Crude
39.31
45.42
(%)
Percent Recovery Purified
32.26
35.81
(%)
Pure Melting Point (°C)
158.3-160.3
38.6-42.5
Table 2 outlines the results obtained from the simple distillation of two unknown
miscible liquids. After distilling unknown liquid # 8, the two separate liquids were then
characterized by boiling point and density.
Table 2: Results from the Simple Distillation of Unknown Liquid #8
Unknown Mixture # 8
Low Boiling Liquid
High Boiling Liquid
Physical Composition
Clear liquid, Sharp odor, Low viscosity
Mass of Original Mixture
15.6911
(g)
Mass of Separated Product
4.0721
11.0071
(g)
Percent Recovery (%)
96.10
Boiling Point (°C)
56.8-57.1
80.2-82.5
Density (g/mL)
0.4566
0.7823
Unknown liquid # 8 was clear and had a low viscosity. Upon heating, it released
a sharp odor. After the simple distillation the percent recovery of unknown liquid # 8
was 96.10%. The separate liquids were then heated to determine the temperature at
which each boiled. This temperature was also the most stable temperature. The boiling
point for the low boiling liquid was 56.8-57.1°C. The boiling point for the high boiling
liquid was 80.2-82.5°C. Boiling point and density are both physical properties used to
characterize liquid unknown #8. The density of the low boiling liquid was 0.4566 g/mL
while the density for the high boiling liquid was 0.7823 g/mL.
Table 3 outlines the results obtained from mass spectrometry of the low boiling
and high boiling liquids of unknown #8 and the neutral and carboxylic acid solids of
unknown #20. The peaks in the spectrum were analyzed to determine possible lost
fragments and the IHD was calculated.
Table 3: Mass Spectral Data for Unknown Liquid #8 and Unknown Solid #20
Unknown Liquids
Unknown Solids
Unknown code
#8 Low
#8 High
#20 COOH
#20 Neutral
Boiling
Boiling
Molecular formula
C2H3N
C4H10O
C7H5O2Br
C13H10O4
IHD
2
0
5
9
M+ (m/z)
41
74
200
182
Base Peak (m/z)
41
56
200
105
Lost Fragment
N/A
M-18
N/A
M-77
Other Peak(s) (m/z)
40, 39,14
41, 31, 27 183,155,75,50
77, 51
Lost Fragment
M-1, M-2, M-33, M-43, M-17, M-45,
M-105, MM-27
M-47
M-125, M-150 131
The mass spectrum for low boiling unknown liquid #8 expressed a molecular ion
peak (M+) peak at m/z of 41, which also happened to be the base peak. The spectrum
also showed significant peaks at m/z 40, 39, and 14 with lost fragments at M-1, M-2, and
M-27 respectively. The molecular formula was determined to be C2H3N with an IHD of
2. The mass spectrum for the high boiling unknown liquid #8 expressed a molecular ion
peak (M+) at m/z of 74 and a base peak at m/z of 56, which corresponds to a lost fragment
of M-18. The spectrum also showed significant peaks at m/z 41, 31, and 27 with lost
fragments of M-33, M-43, and M-47 respectively. The molecular formula was
determined to be C4H10O with an IHD of 0. The mass spectrum for the carboxylic acid
unknown solid #20 expressed a molecular ion peak (M+) and a base peak at m/z 200.
There were other significant peaks at m/z 183, 155, 75, and 50 with corresponding lost
fragments at M-18, M-46, M-126, and M-151 respectively. The molecular formula was
determined to be C7H5O2Br with an IHD of 5. The mass spectrum for the neutral solid
unknown #20 expressed a molecular ion peak (M+) at m/z of 182 and a base peak at m/z
of 105, which corresponds to a lost fragment of M-77. There were other significant
peaks at m/z 77 and 51, with lost fragments of M-105 and M-131 respectively. The
molecular formula was determined to be C13H10O4 with an IHD of 9.
Table 4 outlines the results obtained from IR spectroscopy of the low boiling and
high boiling liquids of unknown #8 and the neutral and carboxylic acid solids of
unknown #20. The unknowns were characterized by the wavenumber, intensity, and
shape of the peaks present in the spectra.
Table 4: IR Spectral Data for Unknown Liquid #8 and Unknown Solid #20
Unknown Liquids #8
Unknown Solids #20
Low Boiling
High Boiling
R-Z
R-COOH
Wavenumber
(cm-1)
3600
3000
2250
1450
-
Intensity/
Shape
Low
intensity,
dull
Medium
intensity,
sharp
High
intensity,
sharp
Medium
intensity,
broad
Wavenumber
(cm-1)
3320
-
-
2970
1495
1100
Intensity/
Shape
High
intensity,
broad
High
intensity,
sharp
Medium
intensity,
sharp
Medium
intensity,
sharp
Wavenumber
(cm-1)
3100
Intensity/Shape
1680
High intensity,
sharp
1700
1495
Medium
intensity, sharp
1550
1300
High intensity,
sharp
1495
-
1290
High intensity
sharp
1300
Low intensity,
sharp
Wavenumber
(cm-1)
3000
Intensity/
Shape
Medium
intensity,
dull
High
Intensity,
sharp
Medium
intensity,
sharp
Medium
intensity,
sharp
High
intensity,
sharp
The low boiling unknown liquid #8 spectra expressed a low intensity, dull
absorption band at 3600 cm-1 and a high intensity, sharp absorption band at 2250 cm-1.
There were other significant bands at 3000 cm-1 and 1450 cm-1. The high boiling
unknown liquid #8 spectra showed a high intensity, broad absorption band at 3320 cm-1
and high intensity, sharp band at 2970 cm-1. There were other significant bands at 1495
cm-1 and 1100 cm-1. The neutral unknown solid # 20 spectra expressed a low intensity,
sharp absorption band at 3100 cm-1 and a high intensity, sharp band at 1680 cm-1. There
were other notable bands at 1495 cm-1, 1300 cm-1, and 1290 cm-1. The carboxylic acid
unknown solid #20 spectra showed a medium intensity, dull absorption band at 3000 cm-1
and a high intensity, sharp band at 1700 cm-1. There were other notable bands at 1550
cm-1, 1495 cm-1, and 1300 cm-1.
Table 5 outlines the results obtained from the 1H NMR and 13C NMR for the low
boiling and high boiling liquids of unknown #8 and for the carboxylic acid and neutral
solid of unknown #20. The spectra were analyzed by chemical shift, multiplicity, and
integration values.
Table 5: 1H NMR and 13C NMR Spectral Data for Unknown Liquid #8 and Unknown
Solid #20
1H NMR Data
13C NMR Data
Unknown
𝛿 (ppm)
𝛿(ppm)
M
I
Low Boiling Liquid # 8
2
s
3h
116
High Boiling Liquid # 8
1
t
3h
14
1.5
m
2h
20
2.2
s
2h
34
3.6
t
2h
63
COOH Solid # 20
7.4
t
1h
85
7.7
d
1h
122
8
t
1h
127
8.1
s
1h
130
132
135
166
Neutral Solid # 20
7.5
m
1h
127
7.8
m
2h
130
132
138
196
The 1H NMR spectra for the low boiling unknown liquid #8 expressed one peak
(in pppm) of 𝛿 2 (s, 3h) and the 13C NMR expressed one peak at 116 ppm. The 1H NMR
spectra for the high boiling unknown liquid #8 showed four peaks (in ppm): 𝛿 1 (t, 3h),
1.5 (m, 2h), 2.2 (s, 2h) and 3.6 (t, 2h). The 13C NMR spectra for the high boiling liquid
also showed four peaks (in ppm): 𝛿 14, 20, 34, and 63. The 1H NMR spectra for the
carboxylic acid unknown solid #20 expressed four peaks (in ppm): 𝛿 7.4 (t, 1h), 7.7 (d,
1h), 8 (t, 1h), and 8.1 (s, 1h). The 13C NMR spectra for the carboxylic acid solid showed
seven peaks (in ppm): 𝛿 85, 122, 127, 130, 132, 135, and 166. The 1H NMR for the
neutral unknown solid #20 expressed two peaks (in ppm): 𝛿 7.5 (m, 1h) and 7.8 (m, 2h).
The 13C NMR for the neutral solid expressed five peaks (in ppm): 𝛿 127, 130, 132, 138,
and 196.
DISCUSSION/CONCLUSION:
The unknown liquid #8 was separated and purified by simple distillation and then
identified using a combination of mass spectrometry, infrared spectroscopy, and 1H NMR
and 13C NMR techniques. The unknown solid #20 was separated and purified by liquidliquid extraction and recrystallization, and then identified also by using a combination of
mass spectrometry, infrared spectroscopy, and 1H NMR and 13C NMR techniques.
Unknown liquid #8 was separated into a high boiling (80.2-82.5°C) liquid with a
density of 0.7823 g/mL and low boiling (56.8-57.1°C) liquid with a density of 0.4566
g/mL. Both of these liquids were clear and had a low viscosity and sharp odor. The
percent recovery was 96.10%. A loss of product most likely occurred during the transfer
from vial to round bottom flask in the first step. The mass spectra for the high boiling
point revealed a molecular ion peak (M+) at m/z 74, meaning the compound has a
molecular mass of 74 g/mol. The base peak was at m/z 56 meaning the lost fragment was
most likely H2O. There was also a significant peak at m/z 31, which corresponds to an
OCH3 fragment. Therefore, keeping this in mind, the molecular formula was determined
to be C4H10O with an IHD of 0, meaning there were no triple bonds, double bonds, or
rings. The IR spectra revealed an O-H bond with a broad absorption band at 3320 cm-1,
and encouraged the idea that there were no rings, double bonds, or triple bonds due to the
lack of bands in those regions. The proton and carbon NMR each revealed four unique
sets of hydrogens and carbons respectively. Therefore, the high boiling liquid for
unknown #8 was determined to be 1-butanol. This is a clear, water soluble liquid with a
boiling point of 117.6°C and a melting point of -89°C°.13 The difference seen in literature
values versus experimental values in boiling point are potentially due to human error.
The high boiling liquid would jump between 80°C and 82.5°C and would not go any
higher. Therefore, this was determined to be the boiling point range.
The mass spectra for low boiling liquid unknown #8 expressed a molecular ion
peak (M+) at m/z 41. This means that the compound has a molecular mass of 41 g/mol
and most likely contains a nitrogen due to the odd molecular ion peak. The molecular ion
peak was also the base peak, meaning the total compound was the biggest fragment.
There were other peaks at m/z 40 and m/z 39, which most likely represent the loss of
hydrogens. The first peak on the spectrum, at m/z 14 represents a nitrogen fragment.
From the mass spectra the molecular formula C2H3N was determined. This formula gave
an IHD of 2, meaning a triple bond is likely. The IR spectra agreed with this analysis
with a high intensity sharp peak at 2250 cm-1. This peak corresponds to the presence of a
nitrile group. The proton and carbon NMR expressed one unique hydrogen and one
unique carbon respectively. Therefore, the low boiling compound was determined to be
acetonitrile. Acetonitrile is a colorless, water soluble liquid that boils at 81-82°C and
melts at -48°C.14
The solid unknown #20 was separated into a neutral organic solid and a
carboxylic acid solid. In order to get the solid to dissolve before extraction, double the
recommended solvent, dichloromethane, was used. This meant that extraction was done
twice. Therefore, smaller amounts of the liquid were being extracted at one time making
the extraction more precise. The crude carboxylic acid solid had a percent recovery of
39.31% with a loss of product in the drying process and on the sides of the Erlenmyer
flask during filtration. After recrystallization, the carboxylic acid solid was powdery and
white with a percent recovery of 32.26%. The loss of product this time was due to
vacuum filtration. The melting point of the pure carboxylic acid solid was 158.3160.3°C. The mass spectra for the carboxylic acid solid expressed a molecular ion peak
at m/z 201, which indicates a nitrogen. However, upon closer inspection, this molecular
ion peak is incorrect, the actual peak is at m/z 200 and the compound does not contain a
nitrogen. There was a M+1 peak nearly the same height of the M+ peak indicating the
presence of Br. The base peak was also m/z 200. It expressed other significant peaks at
m/z 183 and 155, which correspond to an OH fragment and a OCH2CH3 fragment.
Therefore, based off of the mass spectra the molecular formula C7H5O2Br was
determined. This formula corresponds to an IHD of 5, indicating the possibility of four
double bonds and a ring. The IR spectra showed a medium intensity, sharp absorption
band at 1550 cm-1 indicating the presence of a ring also. The proton and carbon NMR
also indicated a ring because the peaks were in between 7 and 8 ppm for the proton
spectra and between 120 and 140 ppm for the carbon spectra. Therefore, the carboxylic
acid solid was determined to be 3-bromo benzoic acid. This solid is a white to yellow
powder with a melting point of 155-158°C.15
The crude neutral solid had a percent recovery of 45.42% with a loss of product
due to product on the walls of the Erlenmyer flask during vacuum filtration. The purified
neutral solid was crystalline and off-white in appearance with a percent recovery of
35.81%. This loss of product was also due to the vacuum filtration and the transfer of
filter paper to watch glass. The mass spectra showed a molecular ion peak at m/z 182 and
a base peak at m/z 105. The lost fragment here is most likely a benzene ring with an M77. There was another notable peak at m/z 77, indicating the presence of another benzene
ring. Therefore, the molecular formula determined from the MS was C13H10O and had an
IHD of 9. The IHD of 9 indicates two rings and seven double bonds. The IR reveals the
presence of ring also with a medium intensity, sharp band at 1600 cm-1, and a carbonoxygen double bond with a high intensity, sharp peak at 1680 cm-1. Both of the proton
and carbon NMR spectra reveal the presence of rings in the neutral compound because all
of the peaks in the proton NMR are between 7-8 ppm and all but one of the peaks in the
carbon NMR appear between 128-140 ppm. Therefore, the neutral solid was determined
to be benzophenone. Benzophenone is a white solid with a melting point of 47-51°C.16
EXPERIMENTAL:
Lab 2: The Separation of Two Liquid Unknowns by Simple Distillation:
Unknown # 8 was obtained. The mass of the distillation flask with five boiling
stones and the mass of the receiving flask were obtained before the addition of the liquid
unknown. A simple distillation apparatus was built, and the distillation flask was covered
in glass wool. The distillation flask was heated with a heating mantle and once
condensation began to form on the thermometer tip, the temperature was watched closely.
The low boiling liquid was collected in the receiving flask and the stabilized vapor
temperature was recorded. Once the temperature dropped the distillation flask was
removed from the heating mantle and cooled to room temperature. The mass of both the
distillation flask and the receiving flask were taken again and a percent recovery was
calculated. Both liquids were poured out of the respective flasks and into two different
vials labeled with name, date, section number, and contents.
To determine the boiling point of the separated liquids two milliliters of the low
boiling point liquid was poured into a test tube containing boiling chips. The test tube
was placed into an aluminum heating block and clamped into place, ensuring that the
bottom of the test tube did not touch the hot plate. A thermometer was clamped into
place to prevent it from touching any part of the test tube. The liquid was then heated
until the temperature stabilized for at least one minute. This was the boiling point of the
low boiling point liquid. These steps were repeated for the high boiling point liquid.
One milliliter volumetric flasks were obtained, rinsed with acetone, and allowed
to dry. The mass of the empty volumetric flask was obtained. A Pasteur pipette was
used to deliver one milliliter of one of the unknown liquids into the volumetric flask, and
then both flask and liquid were massed. The mass and volume were used to determine
the density of the liquid. These steps were repeated for the other unknown liquid.
Lab 3: The Separation of Two Solid Unknowns by Acid-Base Extraction:
Unknown solid # 20 was massed (5.0017g ) and transferred into a 125 mL
Erlenmyer flask. Dichloromethane (CH2Cl2) was measured (110.4 mL) and poured into
the Erlenmyer flask and the mixture was swirled and stirred with a glass stir rod to
dissolve the solid. Once the solid completely dissolved, half of this mixture was poured
into a separatory funnel and 20 mL of 1.0 M sodium hydroxide (NaOH) was added.
Making sure the stopcock was closed, the funnel was then inverted and shaken for ten
seconds and then vented. This process was repeated until venting produced no sound.
The separatory funnel was then placed in a ring stand and left to settle undisturbed so the
two liquids could separate. Once a clear separation was visible, the organic phase was
drained into a beaker below the funnel, and the top layer (the aqueous phase) was poured
into a separate beaker. The organic phase was then poured back into the separatory
funnel, 20 mL of NaOH was added and the mixture was shaken and vented. The organic
phase was once again drained into a beaker and the aqueous phase was poured out the top
into the beaker with the aqueous phase from the previous extraction. This process was
repeated once more for this half of the original mixture, and then three more times for the
second half of the original mixture.
In order to precipitate out the carboxylate salt, 23 mL of 6.0 M hydrochloric acid
(HCl) was added to the aqueous phase and set on ice. To precipitate out the organic
phase, magnesium sulfate (MgSO4), a drying agent, was added until it stopped clumping
and the beaker appeared to look like a snow globe. The organic phase was then vacuum
filtered through a Buchner funnel to separate the drying agent from the product. The
filtrate was then poured into a 100 mL round-bottom flask and then placed in a rotary
evaporator until only 1-2 mL of solution remained. This solution was then poured into a
massed vial and dried. The aqueous phase, still sitting on ice, was then vacuum filtered
through a Buchner funnel and the solid product was rinsed with 7 mL of ice-cold water.
After running the vacuum for ten minutes, the solid carboxylic acid was scraped with a
spatula onto a labeled watch glass and put in the oven to dry for fifteen minutes. The
watch glass was then cooled to room temperature and the carboxylic acid was poured into
a massed vial.
Lab 4: The Purification and Characterization of Two Unknown Solids by
Recrystallization and Melting Point:
The mass of both crude solids was obtained and a percent recovery was
calculated. In order to recrystallize the carboxylic acid 75 mL of 2:1 MeOH: H2O was
poured into a 150 mL Erlenmyer flask with boiling stones and then heated on a hot plate.
The carboxylic acid solid was poured into a beaker and the hot 2:1 MeOH: H2O was
slowly poured over the solid until it started to dissolve. The beaker was then placed on
the hot plate and covered with a watch glass. Solvent was added dropwise until the solid
dissolved. The solution was cooled to room temperature and then cooled in an ice-water
bath along with at least 5 mL of the solvent used to dissolve the solid. The solid was then
separated from the solution by vacuum filtration through a Buchner funnel and rinsed
with 5 mL of the cold solvent. The solid was placed onto a massed watch glass and set in
a 110°C oven for twenty minutes. All steps were repeated for the neutral organic solid
except that it was dissolved in only 25 mL of ethanol and it was not placed in the oven to
dry. Each purified solid was transferred into a massed and labeled vial and the pure
percent recovery was calculated. To determine the melting points for the pure
compounds two melting point samples were obtained using a capillary tube and the MelTemp apparatus.
Lab 5: Determination of Molecular Weight and Connectivity by Mass Spectrometry, Lab
6: Infrared Spectroscopy and Functional Group Determination, Lab 7: NMR
Spectroscopy:
The topics of mass spectrometry (MS), infrared spectroscopy (IR), and nuclear
magnetic resonance spectroscopy (NMR) were lectured on during the lab time.
Worksheets were passed out to practice the techniques discussed in lab. The unknown
samples were not prepared.
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(8) Wahrenburg, Zach. CHE 231: Mechanistic Organic Chemistry 1 Lab.
https://d2l.depaul.edu/d2l/le/content/280024/viewContent/1804733/View
(accessed March 10, 2014).
(9) Yarris, Lynn. New Clues from Infrared Forensics. http://www.lbl.gov/ScienceArticles/Archive/ALS-IR-Forensics.html (accessed March 19, 2014)
(10) Wahrenburg, Zach. CHE 231: Mechanistic Organic Chemistry 1 Lab.
https://d2l.depaul.edu/d2l/le/content/280024/viewContent/1804734/View
(accessed March 15, 2014).
(11) Nuclear Magnetic Resonance Spectroscopy.
http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/nmr/
nmr1.htm (accessed March 19, 2014).
(12) Michigan State University 900 MHz NMR Facility.
http://www2.chemistry.msu.edu/facilities/nmr/900MHz/MCSB_NMR_applications.
html
(accessed March 19, 2014).
(13) Chemical Book: 1-butanol.
http://www.chemicalbook.com/ChemicalProductProperty_EN_CB9113046.htm
(accessed March 19, 2014).
(14) Chemical Book: acetonitrile.
http://www.chemicalbook.com/ChemicalProductProperty_EN_CB2127174.htm
(accessed March 19, 2014).
(15) Chemical Book: 3-bromo benzoic acid.
http://www.chemicalbook.com/ProductChemicalPropertiesCB0441823_EN.htm
(accessed March 19,2014).
(16) Chemical Book: benzophenone.
http://www.chemicalbook.com/ProductChemicalPropertiesCB5744679_EN.htm
(accessed March 19, 2014).
APPENDICES:
Calculations:
1. In order to calculate the percent recovery of unknown liquid #8 after simple
distillation, add the masses of the separated low boiling liquid and high boiling
liquid together. Then divide this sum by the original mass of the mixture and
multiply the answer by one hundred percent.
𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (%) =
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡𝑠 (𝑔)
× 100%
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑚𝑖𝑥𝑡𝑢𝑟𝑒 (𝑔)
11.0071g +4.0721g = 15.0792 g
𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (%) =
15.0792𝑔
× 100%
15.6911𝑔
𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 = 96.10%
2. In order to calculate the densities of both the low boiling liquid and the high
boiling liquid the mass of 1 mL of each component was divided by the volume of
each component (1 mL).
𝐷=
𝑚
𝑣
𝐷𝑙𝑜𝑤 𝑏𝑜𝑖𝑙𝑖𝑛𝑔 𝑙𝑖𝑞𝑢𝑖𝑑 =
0.4566 𝑔
1 𝑚𝐿
𝐷𝑙𝑜𝑤 𝑏𝑜𝑖𝑙𝑖𝑛𝑔 𝑙𝑖𝑞𝑢𝑖𝑑 = 0.4566 𝑔/𝑚𝐿
𝐷ℎ𝑖𝑔ℎ 𝑏𝑜𝑖𝑙𝑖𝑛𝑔 𝑙𝑖𝑞𝑢𝑖𝑑 =
0.7823𝑔
1 𝑚𝐿
𝐷ℎ𝑖𝑔ℎ 𝑏𝑜𝑖𝑙𝑖𝑛𝑔 𝑙𝑖𝑞𝑢𝑖𝑑 = 0.7823 𝑔/𝑚𝐿
3. In order to determine the percent recoveries for both the crude carboxylic acid
solid and the crude neutral organic solid the mass of the component was divided
by the mass of the mixture. This answer was multiplied by one hundred percent.
𝐶𝑟𝑢𝑑𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (%) =
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐𝑟𝑢𝑑𝑒 𝑐𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡
× 100%
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑚𝑖𝑥𝑡𝑢𝑟𝑒
𝐶𝑟𝑢𝑑𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (𝑐𝑎𝑟𝑏𝑜𝑥𝑦𝑙𝑖𝑐 𝑎𝑐𝑖𝑑 𝑠𝑜𝑙𝑖𝑑) =
1.9663 𝑔
× 100%
5.0017 𝑔
𝐶𝑟𝑢𝑑𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (𝑐𝑎𝑟𝑏𝑜𝑥𝑦𝑙𝑖𝑐 𝑎𝑐𝑖𝑑 𝑠𝑜𝑙𝑖𝑑) = 39.31%
𝐶𝑟𝑢𝑑𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (𝑛𝑒𝑢𝑡𝑟𝑎𝑙 𝑜𝑟𝑔𝑎𝑛𝑖𝑐 𝑠𝑜𝑙𝑖𝑑) =
2.2717 𝑔
× 100%
5.0017 𝑔
𝐶𝑟𝑢𝑑𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (𝑛𝑒𝑢𝑡𝑟𝑎𝑙 𝑜𝑟𝑔𝑎𝑛𝑖𝑐 𝑠𝑜𝑙𝑖𝑑) = 45.42 %
4. In order to determine the percent recoveries for the pure solids carboxylic acid
and neutral organic the mass of the pure components after recrystallization and
purification was divided by the original mass of the mixture and multiplied by one
hundred percent
𝑃𝑢𝑟𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 =
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑝𝑢𝑟𝑒 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑 (𝑔)
× 100%
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑚𝑖𝑥𝑡𝑢𝑟𝑒 (𝑔)
𝑃𝑢𝑟𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (𝑐𝑎𝑟𝑏𝑜𝑥𝑦𝑙𝑖𝑐 𝑎𝑐𝑖𝑑 𝑠𝑜𝑙𝑖𝑑) =
1.6135𝑔
× 100%
5.0017𝑔
𝑃𝑢𝑟𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (𝑐𝑎𝑟𝑏𝑜𝑥𝑦𝑙𝑖𝑐 𝑎𝑐𝑖𝑑 𝑠𝑜𝑙𝑖𝑑) = 32.26%
𝑃𝑢𝑟𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (𝑛𝑒𝑢𝑡𝑟𝑎𝑙 𝑜𝑟𝑔𝑎𝑛𝑖𝑐 𝑠𝑜𝑙𝑖𝑑) =
1.7913𝑔
× 100%
5.0017𝑔
𝑃𝑢𝑟𝑒 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑒𝑐𝑜𝑣𝑒𝑟𝑦 (𝑛𝑒𝑢𝑡𝑟𝑎𝑙 𝑜𝑟𝑔𝑎𝑛𝑖𝑐 𝑠𝑜𝑙𝑖𝑑) = 35. 81%
5. In order to calculate the index of hydrogen deficiency (IHD) the number of
carbons was multiplied by two. The number of Nitrogens plus two was added to
this number. The number of hydrogens and the number of halogens were
subtracted from this total. This final number was divided by two.
𝐼𝐻𝐷 =
2𝐶 + 2 − 𝐻 − 𝑥 + 𝑁
2
𝐼𝐻𝐷𝑙𝑜𝑤 𝑏𝑜𝑖𝑙𝑖𝑛𝑔 𝑙𝑖𝑞𝑢𝑖𝑑 =
2(2) + 2 − 3 + 1
2
IHDlow boiling liquid = 2
𝐼𝐻𝐷 𝐻𝑖𝑔ℎ 𝐵𝑜𝑖𝑙𝑖𝑛𝑔 𝐿𝑖𝑞𝑢𝑖𝑑 =
2(4) + 2 − 10
2
IHDHigh Boiling Liquid = 0
𝐼𝐻𝐷𝐶𝑂𝑂𝐻 =
2(7) + 2 − 5 − 1
2
IHDCOOH = 5
𝐼𝐻𝐷𝑁𝑒𝑢𝑡𝑟𝑎𝑙 =
2(13) + 2 − 10
2
IHDNeutral = 9