EXP5-Synthesis Of Acipic acid form Cyclohexanol PDF

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Experiment 5 on Synthesis Of Acipic acid form Cyclohexanol...

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Page 1

EXP-5

CHEM 233L SYNTHESIS OF ADIPIC ACID FROM CYCLOHEXANOL

Introduction: Adipic acid is a white crystalline solid used primarily in the manufacture of nylon 6, 6 polymers for fibers and plastics. In this experiment, adipic acid was synthesized in two steps starting from cyclohexanol. Cyclohexanol was first oxidized to cyclohexanone using sodium hypochlorite. The intermediate product cyclohexanone was then further oxidized to adipic acid using hot potassium permanganate. Both steps were oxidation reactions.

Main reactions:

RXN-1: Preparation of cyclohexanone

OH

O HOCl

RXN-2: Preparation of Adipic Acid

O KMnO4

O HO OH O

Page 2 Table of physical data:

Compound name Molecular Melting Boiling Density Weight point point (oC) (g/ml) (oC) (g) OH 100.160 23-25 161 0.962

Physical Properties

Colorless, viscous liquid or sticky solid with a faint camphor odor. HYGROSCOPIC.

Cyclohexanol Na+

74.442

-O

1.209

Cl NaOCl O

60.052

16.6

104.056

150

98.144

-47

117.9

1.0492

OH HOAc O

1.48

Na+ S HO

O-

Colorless liquid or solid with a strong vinegar-like odor detectable at 0.2 to 1.0 ppm. HYGROSCOPIC. Usually present as a mixture of sodium bisulfite and sodium meta-bisulfite. AIR SENSITIVE.

NaHSO3 Cyclohexanone O

155.6

0.947

Safety Notes:  

Ether is flammable, keep under the hood. Cyclohexanone is a flammable liquid. Don’t put it close to flame.

Oily, white to slightly yellow liquid with a peppermint-like odor.

Page 3 Procedure: Part A: PREPARATION OF CYCLOHEXANONE: 1.

Place about 10.0g of cyclohexanol (10.4 ml, 0.1 mole) in a 250-mL Erlenmeyer flask and then put 25-mL of glacial acetic acid in as well. Place the flask in an ice bath. 2. Use a separatory funnel; Add 75-mL of 5% NaOCl solution (Clorox) dropwise in the flask, with occasional swirling while keeping the temperature at 30 to 35 oC. Swirl the mixture well and return to the ice bath. 3. Add another 75 ml of 5% NaOCl dropwise. At this point the mixture should give a positive reaction with potassium iodide-starch paper. If it does not, add more NaOCl solution (1 to 5mL) until a positive reaction is obtained. 4. Let the mixture stand at room temperature for 15 minutes. 5. Add saturated sodium bisulfite solution until a negative potassium iodine-starch test was given. 6. Transfer the mixture to a 250 mL distilling flask and distill until the distillate is free of droplets (approximately 75 mL). For convenience, collect the distillate in a 250 mL Erlenmeyer flask. 7. To free the distillate of any acetic acid, add anhydrous sodium carbonate carefully with stirring until foaming ceases. 8. Then add 8 g of sodium chloride and stir approximately 10 minutes to further salt out the cyclohexanone. 9. Decant the mixture into a separatory funnel 10. Add the ether to extract the cyclohexanone. 11. Dry the product by anhydrous magnesium sulfate and decant through a cotton plug into a 25 mL distilling fraction boiling at 150 to 155 oC in a tarred receiver. 12. Weigh the product and calculate the percent yield. Examine the product by infrared spectroscopy. 13. Save the required amount of product for the next step and submit the rest in a tarred vial. Part B: PREPARATION OF ADIPIC ACID 1. Dissolve 8.0 g of solid Potassium Permanganate (KMnO4) in 30-50 ml of H2O in a 250 ml Erlenmeyer flash. 2. Add 8 to 10 ml of cyclohexanone product from part A into the flask. 3. Heat the mixture to 30 0C on a hot plate 4. Add 1 ml of 3 M NaOH solution. 5. Add a stirring bar and place reaction on a stirring platform. 6. Let the temperature rise to 45 0C, which should take 15 minutes. Note: slow stirring will lower temperature, but more rapid stirring will increase temperature. 7. Alternatively, use an ice bath and a hot plate to maintain the temperature of the reaction mixture at 45 0C for 20 minutes. 8. Heat the reaction mixture to coagulate the Manganese Dioxide.

Page 4 9.

Perform a spot test by dipping a stirring rod in the mixture and applying to a piece of filter paper. If the paper turns purple, then excess Permanganate needs to be reduced. 10. If unreacted Permanganate remains, add a small portion of Sodium Bisulfite (20 drops), stir and test spot again. Continue this until you get no purple color on filter paper. 11. Filter the mixture through a vacuum filter to remove the Manganese Dioxide residue. 12. Wash the brown precipitate with 5.2 ml of warm water. 13. Transfer the filtrate to a 250 ml beaker and place on hot plate set to high. 14. Evaporate the filtrate down to approximately 10-15 ml. 15. The hot solution was acidified by adding concentrated HCl dropwise (about 1 mL of concentrated HCl) until pH 1-2. (pH paper was used to test). 16. Add an additional 1.5 ml of acid. 17. Allow the solution to cool down and then immerse in an ice bath to crystallize further. 18. Collect the product by vacuum filtration. 19. Allow the crystals to dry overnight. 20. At the next lab period, weigh the dry crystals. 21. Record the weight of the dried crystals as the actual yield. 22. Obtain the melting point and IR spectrum. 23. Save your product to submit to your professor.

Reference: www.chemfinder.com http://ptcl.chem.ox.ac.uk/MSDS Lab#5 handout...