This document describes the synthesis of adipic acid from cyclohexanone via a nitric acid oxidation reaction. The reaction is exothermic and the nitric acid must be added slowly to cyclohexanone. Once complete, the product crystallizes and is washed and dried. The percent yield was 62.33% and melting point was 148-151°C, slightly lower than literature due to residual solvent. Infrared spectroscopy confirmed the product was adipic acid. Safety precautions are described for handling oxidizing and acidic reagents.

1. Adipic acid from cyclohexanone
• By Dr. Robert D. Craig, Ph.D.

2. Message from stockroom
• KMnO4- vessels easily explode-oxidizing
agents support combustion
• The vessels will become hot at the bottom and
splatter
• *bad incident 2 semesters ago

3. THIS IS EXPLOSIVE!!!!

4. PLEASE BE CAREFULL!!!!
• Safety Features:
1. Add concentrated hydrochloric acid to the strongly
basic solutionvery cautiously (or erupting may occur).
Wash the affected area thoroughly with cold water if
acid is spilled on the skin.
2. Handle potassium permanganate carefully. It is a
strong oxidising agent. Avoid contact with skin and
eyes.
3. Avoid breathing vapours of cyclohexene and
methanol

5. Abstract:
• In this experiment, adipic acid was synthesized
from cyclohexanone and concentrated nitric
acid. The HNO3 and cyclohexanone were
combined very slowly, since the reaction is
very exothermic. Once the reaction was
complete, the product was allowed to
crystallize and the solvent was removed.

6. Abstract
• The adipic acid crystals were then washed
with a small amount of water, dried for a
couple days and weighed.

7. THIS IS EXPLOSIVE!!!!

8. From website
• EXP. 8: Elimination Reaction E1: Cyclohexene from cyclohexanol
(fractional distillation)
• EXP. 8: IR spectra of cyclohexanol and cyclohexene
• EXP. 8: IR and NMR Handout
• EXP. 8: Post Lab
• EXP. 9: Elimination Reaction E2: Cyclohexene from
bromocyclohexane
• EXP. 9: Reflux Apparatus (You may bring this handout to lab!)
• EXP. 9: Distillation Apparatus (You may bring this handout to lab!)
and Actual Photo
• EXP. 9: IR and NMR Handout
• EXP. 9: Post Lab

9. The percent yield of this experiment
• The percent yield of this experiment was 62.33%. This
was low because when a Pasteur pipet was used to
remove the solvent from the reaction tube, many
crystals were lost. In addition, some crystals remained
in the reaction tube as well as on the boiling chip and
were not available for weighing. The observed melting
point of the product was 148 - 151°C. This was a little
lower than the literature value of 153°C, which may
have been due to the fact that not all the solvent or
water evaporated from the crystals. An infrared
spectrum of the product confirmed its identity as
adipic acid and indicated that the reaction was
successful.

10. The observed melting point
• The observed melting point of the product
was 148 - 151°C. This was a little lower than
the literature value of 153°C, which may have
been due to the fact that not all the solvent or
water evaporated from the crystals. An
infrared spectrum of the product confirmed its
identity as adipic acid and indicated that the
reaction was successful.

11. Introduction
• The purpose of this experiment is to
synthesize adipic acid from cyclohexanone and
concentrated nitric acid via an oxidation
reaction. The cyclohexanone is oxidized using
nitric acid and thus forms adipic acid. Melting
point and infrared spectroscopy will be used
to characterize the product.

12. Materials Used:
• Sand bath Rubber bulb
• 2, 10 x 100 mm reaction tubes Erlenmeyer
flask, 25-mL
• Boiling chips watch glass
• Pasteur pipettes clamp
• Glass stirring rod ice for ice bath

13. Experiment 12 Preparation of adipic
acid from cyclohexene.
•
In this laboratory period the cyclohexene
prepared in the previous experiment is
oxidised to adipic acid. The procedure is
written for a specific amount of cyclohexene.
Before coming to the laboratory calculate the
amounts of reagents required for the amount
of cyclohexene you have available.

14. Experiment 12 Preparation of adipic
acid from cyclohexene.
• Theory:
The cleavage of double bonds by oxidation is
useful in the synthesis of acids and ketones
and determining structures. Several methods
are available including ozonolysis and hot
concentrated permanganate. The products
obtained depend on the original structure of
the olefin. The equations below illustrate the
products from cleavage of alkenes:

15. Experiment 12 Preparation of adipic
acid from cyclohexene.

16. Experiment 12 Preparation of adipic
acid from cyclohexene.
• The balanced equation for the oxidation of
cyclohexene with permanganate is shown:

17. Technical Points
•
Vacuum Drying of Organic Solids
Organic solids may be dried by allowing air to
pass through the filtering apparatus for a few
minutes. This, however, only works well when
the solvent used for crystallization has a low
boiling point. A very effective method of
rapidly drying materials isolated from high
boiling

18. Technical Points
• liquids is to heat them under vacuum. A
simple way of carrying out such an operation
on a small quantity of material involves using
a side arm test tube. The material to be dried
is placed in the bottom of such a tube, which
is then stoppered with a cork. The side arm is
connected to the water aspirator.

19. always DISCONNECT the hose
• The vacuum is turned on and the test tube is
heated gently in the steam bath. The test tube
is shaken regularly until the solid looks dry and
no longer sticks to the walls of the tube.
Remember to always DISCONNECT the hose
from the test tube before turning off the
water!

20. always DISCONNECT the hose
• Remember to always DISCONNECT the hose
from the test tube before turning off the
water!

21. concentrated hydrochloric acid
• Safety Features:
1. Add concentrated hydrochloric acid to the strongly
basic solutionvery cautiously (or erupting may occur).
Wash the affected area thoroughly with cold water if
acid is spilled on the skin.
2. Handle potassium permanganate carefully. It is a
strong oxidising agent. Avoid contact with skin and
eyes.
3. Avoid breathing vapours of cyclohexene and
methanol

22. Procedure:
• Procedure:
To a 250 mL Erlenmeyer flask, add water (50 mL),
cyclohexene (2 mL, density = 0.81 g cm-3), and
potassium permanganate (8.4 g). Stopper the flask
loosely, wrap with a towel and swirl vigorously for 5
minutes. The flask should feel warm.
(If no rise in temperature is detected, remove the
stopper, warm the mixture on the steam bath and
loosely replace the stopper).
Swirl the flask at frequent intervals for 20 minutes
(your yield depends on how well you mix the reactants
at this stage).

23. THE BOTTOM WILL GET HOT!!!

24. IT CAN EXPLODE!!!
• The temperature of the mixture should be
between 35° and 40°.
•
If the temperature rises above 45°, briefly cool
in an ice-water bath. Remove the stopper and
place the flask on a steam bath for 15
minutes.

25. • Continue to swirl the flask at frequent
intervals.
Make a spot test by withdrawing some of the
reaction mixture on the tip of a stirring rod
and touching it to a filter paper;
permanganate, if present will appear as a
purple ring around the dark brown spot of
manganese dioxide

26. Filter the mixture through a large
Buchner
• . If permanganate is still present, add 1 mL of
methanol and heat. Repeat this procedure
until the permanganate colour has
disappeared.
.

27. Filter the mixture through a large
Buchner
• Filter the mixture through a large Buchner
funnel (vacuum) into a clean filter flask. Rinse
the reaction flask with 10 mL of hot 1%
sodium hydroxide solution and pour through
the filter. Repeat with a second portion of 10
mL of 1% sodium hydroxide solution.

28. Filter the mixture through a large
Buchner

29. acidify to about pH 1 by cautiously
• Place the filtrate and washings in a 250 mL beaker
(premarked at 10 mL), add a boiling chip and boil over
a flame until the volume of the solution is about 10 mL.
Cool the solution in an ice-water bath and acidify to
about pH 1 by cautiously adding concentrated
hydrochloric acid dropwise while stirring the solution.
(SAFETY GLASSES!) Add an additional 3 mL of acid, stir
and allow the beaker to stand in the ice bath for 5 - 10
min to complete the crystallisation.

30. Recrystallize
• Collect the acid by vacuum filtration.
Recrystallize it from not more than 5 mL of
boiling water (if 2 mL of cyclohexene was
used). Cool to room temperature, then place
in an ice-water bath for 10 minutes.

31. Recrystallize

32. Recrystallize
• Filter the product by vacuum (Hirsch funnel)
and dry as described under Technical Points.
Measure the melting point and yield of
product. Calculate the percentage yield.
Submit your sample in a labelled vial along
with your report.

33. Infrared Spectroscopy
On your worksheet indicate the important
differences in the i.r. spectrum of the starting
material and product. Relate the values of these
absorptions to the structures of the compounds
(see Appendix 3).
Animations of the vibrational modes have been
calculated for both cyclohexene and adipic acid.

34. VIBRATIONAL MODES
• http://wwwchem.uwimona.edu.jm/spectra/JS
pecView/iranim/index.html