Experiment #12 - Organic Chemistry
Objectives: You will learn the different classes of organic compounds. You will then synthesize
Aspirin, Nylon 6-10 and three different esters.
Safety glasses are required for this experiment.
Textbook reference: pp 516-517
Part 1: Classes of Organic Compounds
Several different organic compounds will be passed around the laboratory. Gently waft each
chemical and write down the odor. Also write down the functional groups present in each
compound and any other relevant information that your instructor may discuss.
Name
Structure
Ethyl Alcohol
Functional Groups/
Properties
H
H
H
C
C
H
OH
H
2-Propanol
H
HO
C
H
H
C
C
H
H
H
H
O
Acetone
C
H3C
CH3
Benzaldehyde
H
C
H
H
O
C
C
C
C
C
C
H
H
H
Acetic Acid
O
C
H3C
OH
Ethyl Acetate
O
H2
C
C
H3C
CH3
O
Amyl Acetate
O
H2
C
C
H3C
H2
C
O
C
H2
H
Methyl Salicylate
H
C
H2
O
C
C
C
C
C
H
CH3
CH3
O
C
C
OH
H
H3C
Triethylamine
CH2
H2C
H3C
N
H2C
CH3
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Part 2: Preparation of Aspirin
Aspirin has been widely used as analgesic (pain killer), antipyretic (fever-reducing) and antiinflammatory medicine. Its chemical name is acetylsalicylic acid (IUPAC name: 2(methoxycarbonyl)benzoic acid). In this experiment, you will use salicylic acid, acetic
anhydride and phosphoric acid to synthesize aspirin. An excess amount of acetic anhydride will
be used to enhance the percentage yield of aspirin.
Carboxylic acid
O
O
O
O
O
OH
+
H3PO4
H3C
O
CH3
OH
Salicylic acid
OH
+
heat
70-80°C
Acetic anhydride
H3C
O
O
CH3
OH
Acetic Acid
Ester
Aspirin, an ester/acid
Acetylsalicylic acid
Safety
Acetic anhydride and 85% phosphoric acid are highly corrosive. You must wear gloves and
goggles while doing the experiment. Salicylic acid and aspirin may irritate skin and eyes. Do
NOT breathe acetic anhydride vapor. This experiment should be done under good ventilation,
especially for all transfers.
Waste
The chemicals used in this lab can be disposed of in the sinks with large amount of running
water. Un-reacted acetic anhydride will be hydrolyzed to vinegar and 85% phosphoric acid will
be highly diluted with running water.
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Apparatus set-up for the experiment
Erlenmeyer flask
Buchner funnel
beaker
filter flask with side arm
vacuum
5
4
6
5
7
8
3
2
9
2
1
11
6
4
3
7
8
hot plate
9
1
10
Apparatus for running reaction
Apparatus for vacuum filtration
Procedure
1. In a 125 ml Erlenmeyer flask, you will be given 2 g of salicylic acid.
2. Under a fume hood, add 6 ml of acetic anhydride to the Erlenmeyer flask with salicylic acid.
Then, carefully add 6 drops of 85% phosphoric acid to the same flask.
3. Gently swirl your flask to make sure the reagents are well mixed. Place your Erlenmeyer flask
in a 70 to 80 °C warm water bath on a hotplate. Keep the flask in the warm water bath for 20 to
30 minutes.
4. Remove the Erlenmeyer flask from water bath.
5. Add 40 mL of cold distilled water to your flask quickly. Then, place your flask in an icewater bath and swirl the flask.
6. Gradually, you should see some white crystals at the bottom of the flask placed in the icewater bath. If you do not see white solid or you observe some oil drops, use a stirring rod to
scratch the inside wall of the flask to seed crystals while you use another hand to hold your flask
in the ice-water bath.
7. After your product has crystallized, collect your aspirin crystals by vacuum filtration. While
the vacuum is on, pour the mixture in the flask into the Buchner funnel. Wash your Erlenmeyer
flask twice with some iced-water each time and transfer the water in your flask to the Buchner
funnel.
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Questions
1) Waft the aspirin crystals carefully, can you detect an odor? What is it?
2a) Which functional group in the salicylic acid compound was affected?
2b) What is the new functional group formed?
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Part 3: Preparation of Nylon 6-10 by interfacial polymerization
Introduction
Nylons are polyamides synthesized by condensation polymerization of dicarboxylic acids or
their derivatives (for example, diacyl chlorides) and diamines. Remarkable durability and
flexibility give Nylons extensive applications as synthetic fibers. Nylon 6-10 is made by the
interfacial condensation of 1,6-diaminohexane and sebacoyl chloride under basic conditions.
The name of Nylon 6-10 is derived from the fact that it is prepared by 6-carbon diamine and 10carbon sebacoyl chloride, and the 6-carbon and 10-carbon units alternate and are separated by
nitrogen atoms of the amide groups in the repeating unit of Nylon 6-10.
O
H
H O
N (CH2)6 N C (CH2)8 C
O
O
H2N(CH2)6NH2
ClC (CH2)8 CCl
1,6-diaminohexane
sebacoyl chloride
n
Nylon 6-10
O
n H2N(CH2)6NH2
+
O
n ClC-(CH2)8-CCl
NaOH, - 2n HCl
H
HO
O
N-(CH2)6-N-C-(CH2)8-C
n
Safety
Sodium hydroxide is a strong base and highly corrosive. It can cause severe damage to skin and
eyes. Hexane is a highly volatile organic solvent and must not be used near flame or heat. 1,6diaminohexane is irritating, corrosive and gives off toxic fumes upon being heated. Sebacoyl
chloride is extremely harmful to skin, eyes and respiratory system. You must wear goggles and
gloves when doing this experiment. This experiment must be conducted in well-ventilated fume
hoods or rooms.
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Procedure:
1. To a dry and clean 100-mL beaker, add 20 ml of 5% sebacoyl chloride solution.
2. Slowly add 20 ml of 5% 1,6-diaminohexane in 3 M NaOH solution to the beaker.
3. Let the reaction mixture stand still for one minute. You should see a white film formed at the
interface of the two layers in the 100-mL beaker.
4. Dip forceps into the beaker and let it reach the interface of the two layers. Then, grasp the
white nylon film at the interface area, slowly pull the polymer strand out of the solution and wrap
the strand around the central part of a stirring rod. Hold the rod firmly and slowly wind up your
nylon. If you do it very carefully and slowly, you should be able to obtain an unbroken nylon
strand until one of your reactants is used up. If your nylon strand snaps, use forceps to generate
a new strand.
5. Place the Nylon into a 250-mL water filled beaker.
6. Observe the physical appearance of your product. Test the tensile strength of your nylon
strand by stretching until it breaks.
Questions
1) Where did the reaction take place when the reagents were mixed?
2) Describe the appearance of your Nylon 6-10 product and the tensile strength of your nylon
product (that is, qualitatively how much effort is needed to break the nylon strand).
3) What are some uses of Nylon?
4) Name two natural polymers?
5) Do we have any polymers in our body? Explain.
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Part 4: Synthesis of Esters
You will be synthesizing the three esters you observed in part 1 (ethyl acetate, amyl acetate and
methyl salicylate) by a method called Fischer esterification. In this method, a carboxylic acid
and an alcohol react in the presence of acid to yield an ester and water.
A.
O
O
+
C
H3C
CH3CH2OH
H3PO4
H3C
OH
acetic acid
H2
C
C
ethanol
+
H2O
+
H2O
CH3
O
ethyl acetate
B.
O
O
C
H3C
+
CH3(CH2)4OH
H3PO4
OH
C
H3C
acetic acid
O(CH2)4CH3
amyl acetate
amyl alcohol
O
O
C.
CH3
OH
+
CH3OH
OH
salicylic acid
O
H3PO4
+
H2O
OH
methanol
methyl salicylate
Procedure: Add about 3 mL of the alcohol to the test tube that already contains the carboxylic
acid. Then add 3 drops of phosphoric acid to the test tube and place the test tube in a hot water
bath. Let the reaction proceed until the ester is formed (indicated by the odor you observed in
part 1).
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