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Introduction
Carbonyl compounds  may be oxidized. Some of them udergo oxidation easily,  some require a stronger oxidizer. Aldehydes are easily oxidized, even in the presence of air. Ketones require stronger oxidizing agents, such as potassium dichromate or permanganate.   Organic acids are  produced as a result of  oxidation of ketones.
In this experiment, you will oxidize cyclohexanone to adipic acid using potassium permanganate (KMnO₄).
The oxidation reaction  in a basic environment  follows the equation:

                          C₆H₁₀O (l)   + 2 KMnO_{4 (aq)}   -->   KOOC-(CH₂)₄COOK (aq)  + 2MnO₂ (s)

In the second step, the reaction moxture is  acidified, which results in the conversion of potassium salt  of adipic acid to the acid itself:

                       KOOC-(CH2)4COOK (aq) + 2HCl (aq)  -->  HOOC-(CH2)4COOH  (s) + 2KCl (aq)

Procedure
1. Prepare a hot water bath. To do this, half-fill  a 250 mL beaker  with water, place the beaker (surrounded  by a medium ring attached to the ring stand) on top of a wire gauze placed on the ring above the bunsen burner or simply place the beaker on the hot plate, if such is available. Attach the clamp to the ring stand  in which  the   termometer  will be suspended. Immerse the thermometer in the water in the beaker.

2. Start heating the water, stirring once in a while. Once the temperature of 50 ⁰C has been reached, lower the flame or hot plate setting to maintain that temperature.

3.  Place preweighed 1.6 gram-sample  of potassium permanganate and 10 mL of distilled water in a   largest  test tube.
Note: when weighing, aplly extreme caution as KMnO₄  is an irritant and  oxidizing agent that should not come in contact with your skin or balance! Always use spatula and do not spill any of the reagent.

4. Using a clamp, attach the  tube with the reaction mixture to the stand in such a way that the entire reaction mixture is  immersed in the water. Stirr carefully, using a stirring rod until ALL of the permanganate is  dissolved (extremely important !)

5. Add 0.5 g of sodium carbonate. Stir to dissolve. Using a  calibrated dropping pipet, slowly,drop by drop add 0.5 mL of cyclohexanone.

6. Increase the heat to bring the temperature to 70⁰C and  heat the mixture for about 10 minutes.  The mixture should not be purple anymore, but brown. After heating, let the mixture cool to room temperature.

7. Add 0.1 g of Celite and vacuum-filter the mixture ( do not forget to place a well-fitted circular filter paper in to the Buchner funnel before pouring the reaction mixture into the funnel). Pour the  solution  into a large  test tube and evaporate to about half of the original volume.

8. Cool  the mixture and add concentrated hydrochloric acid, slowly and dropwise until the foaming stops (foaming  results from the excess sodium carbonate reacting with acid to produce carbon dioxide). Test  the solution with a blue (or red) litmus paper. The paper should turn  red ( or remain red)  if enough acid was added.

9. Add another 10 drops of hydrochloric acid and stir.

10. Cool the tube in an ice bath (small beaker with a little tap water and ice). A white solid, adipic acid,  should form.

PRELAB

Postlab Question
1. How did you determine that the cyclohexanone  had undergone oxidation in your experiment ?
Hint: What visual cues indicated that new products were formed throughout the process and in the final stage?