OXIDATION OF CYCLOHEXANOL TO CYCLOHEXANONE

Equation:

NaOCl + CH3CO2H + C6H11OH --> C6H10O + HCl + CH3CO2-Na+  + H2O

Tabled Amounts of Reactants Used and Amounts of Products Theoretically Possible

Compound

C 6 H 11 OH

NaOCl

CH 3 COOH

C 6 H 10 O

MW

100

74.5

60.0

98.0

Moles

 

 

 

 

Grams

 

 

 

 

density

0.962

-

1.049

0.998

ml

10.4

90.0

25.0

 

Concentration

-

10g/dl

17.5M

 

-

 

 1.            Assemble apparatus as shown in the following figure:

 

 2.            BE SURE YOUR FLASK AND CONDENSER ARE CLAMPED TO THE RINGSTAND.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 3.            Add a magnetic stirring bar to your 500 mL round-bottom flask and place a magnetic stirrer beneath the flask. An empty bowl should be placed between the flask and magnetic stirrer, and a supply of ice and water should be on hand for cooling the reaction, if necessary.  Use a 250 mL beaker, and your digital

                thermometer.

4.             Add 10.4 mL cyclohexanol and 25 mL glacial acetic acid into the reaction flask.

 

 5.            Add 90-mL NaOCl (10% w/v) to the dropping funnel.

 

 6.            Begin stirring the contents of your reaction flask and start adding the NaOCl from your dropping funnel dropwise to the reaction flask.  This addition will take 25-45 mins.

 

 7.            Maintain the temperature of the reaction mixture at 30 - 35 oC by controlling the rate of addition of NaOCl and the use of your ice - water bath, whenever necessary.  Do not over-cool your reaction mixture.

 

 8.            After the completion of the NaOCl addition, the reaction mixture should be a greenish-yellow and should give a positive test with KI-starch paper (i.e. placing a drop of your reaction mixture onto the test strip should turn the paper blue or black ).

 9.            If the mixture is not greenish-yellow or does not maintain a greenish-yellow color during subsequent stirring, add sufficient NaOCl (1 - 3-mL) to impart a greenish-yellow color and yield a positive KI-starch test.

 

10.           Remove the cooling bath and stir for fifteen minutes at room temperature.  Add solid NaHSO3 in small portions, until the reaction mixture turns colorless and  gives a negative KI-starch test.

 

11.           Rearrange your apparatus for steam distillation.  (Pennyhead stoppers in the left and right joints, still head in the center joint).

 

12.           Add 60 mL of water to the reaction flask and distill the mixture, collecting the first fifty (50) mL of distillate in a 250 mL Erlenmeyer flask.  This distillate consists of water, acetic acid, and your ketone.

 

13.           Pour the distillate into a separatory funnel, add 5 g of solid NaCl, swirl, allow layers to separate,  and drain off the lower aqueous layer.

 

14.           Wash the organic layer with two - 10 mL aliquots of saturated NaHCO3.

 

           15.                Drain off the lower aqueous layer and transfer the ketone to a 50 mL Erlenmeyer flask and dry the

                                                product over anhydrous MgSO4.

 

16.           Decant the liquid sitting on top of the MgSO4 into another tared 50 mL Erlenmeyer flask.  Weigh the

        Erlenmeyer flask, containing the solution, with a stopper in it.  Record the weight in your notebook and

        make sure it is recorded in the lab report.  Save your product for the Carbonyl tests.

 

Laboratory Report.  Supply the usual, minus the boiling range and B.P., and determine the OH and C=O peaks by looking at the IR spectra on the following pages.

 

 

Cyclohexanol Spectra

 

Assign.     Shift(ppm)




      A             3.58
      B             2.63
      C          1.04 to 2.04
 

 

 

 

 

 

 

 

 

 

 
 


Cyclohexanone Spectra 

 
Assign.     Shift(ppm) 




      A             2.35
      B          2.07 to 1.55

 

 

 

 

 

 

 

 

 

Explanation of Procedure

 

Steps 5-6                HOCl is being generated and is immediately used to oxidize cyclohexanol to cyclohexanone.

 

Step 7                     Above 35oC, "-halogenation of a ketone can occur.    

 

 

Remember HCl+ + HOCl    W Cl2 + H2O

 

Step 9                     If Cl2 is present with HOCl, it is a sign that the alcohol was the limiting reactant.  If NO excess of Cl2 W HOCl present, you don't know if the alcohol was the limiting reactant or not.

 

                                The reaction is

 

                                Cl2 + 2KI ----> 2KCl + I2.

 

                                I2 + starch ----> starch-I2 (blue black).

 

Step 10   Cl2 must be removed now, otherwise it will come out into the room during distillation.  Adding too much NaHSO3 will cause the excess to ----> SO2 & enter the room, making you & your colleagues leave.

 

Step 12   This is a combination steam distillation and simple distillation.  the H2O-ketone distillation is the steam distillation.  The H2O-acetic acid is the simple distillation.

 

Step 13   To "salt-out" the product. (Che 301)

 

Step 13   CH3COOH + NaHCO3 ---> CH3COO-Na+ + [H2CO3]

                                [H2CO3] ---> CO2 + H2O

 

 

Step 15   MgSO4 + nH2O ---> MgSO4 . nH2O (s)