KU Oxidation of Cyclohexanol to Cyclohexanone Lab Report

Oxidation of Cyclohexanol toCyclohexanone
Oxidation
• Alcohols can be oxidized to aldehydes and ketones using oxidizing
agents such as potassium permanganate and sodium hypochlorite
(bleach).
• Primary alcohols are oxidized into aldehydes and then further
oxidized into carboxylic acids.
• However, secondary alcohols are oxidized into ketones.
• While tertiary alcohols will not undergo oxidation at all.
• In this experiment, a secondary cyclic alcohol is oxidized into ketone
using a strong agent such as sodium hypochlorite (bleach).
• Oxidation reactions are important reactions used in organic chemistry
to convert alcohols into ketones which can be further oxidized into
carboxylic acids.
• The oxidation of cyclohexanol begins by generating the hypochlorous acid
which will be the oxidizing agent.
• This is a very strong oxidizing agent, we will be generating it in situ through
the reaction of acetic acid and sodium hypochlorite (regular household
bleach).
• In the next step, the hydrogen on the hypochlorous acid undergoes
nucleophilic attack by the oxygen of the cyclohexanol to form protonated
cyclohexanol and a hypochlorite ion.
• This is followed by nucleophilic attack by the hypochlorite ion and
displacement of water.
• The water then abstracts a hydrogen which initiates a cascade that results
in the chlorine leaving as chloride ion and the generation of
cyclohexanone.
Reaction
Procedure
1. Add 5 ml of cyclohexanol to a 100 ml round bottom flask. Add 15 ml of
glacial acetic acid. Cool the mixture in an ice bath to as close to 0°C as
possible.
2. Add 35 ml of sodium hypochlorite solution to a glass fitted separatory
funnel and attach it to the round bottom flask. Place the thermometer.
Support your apparatus on a magnetic stir motor and adjust the speed so
that it stirs vigorously.
3. Monitor the temperature as the reaction proceeds. Add the hypochlorite
solution slowly to the alcohol solution (within 10-15 minutes). Maintain
the temperature of the reaction at 30-40°C by controlling the rate of
addition on NaOCl and the use of the ice-water bath, whenever
necessary.
4. Remove cooling bath and stir for 15 minutes at room temperature.
5. Add saturated sodium bisulfite (NaHSO3) to remove any yellow color remaining, which
will remove any excess chlorine that I in the solution. The reaction should turn colorless.
6. Rearrange your apparatus for steam distillation. Attach a Claisen adapter and a
condenser to the round bottom flask.
7. Add 20-30 ml of water to the round bottom and distill about 30 ml of distillate into a
graduated cylinder. The distillate should be a mixture of cyclohexanone and water that
contains excess acetic acid. Take note of the boiling point of the cyclohexanone. Transfer
the distilled to a separatory funnel or beaker.
8. Add 3.5 grams of sodium carbonate to neutralize any excess acetic acid, then add a small
amount, about 3 grams of sodium chloride to “salt” out any cyclohexanone from the
aqueous phase. Make sure all solids are completely dissolved. Add to separatory funnel.
9. Separate the layers. Collect the upper cyclohexanone layer in a small beaker and add a
small amount of drying agent (calcium II chlorite). Allow it to set and then decant into a
clean dry, tared weighing bottle.
• 10. Weigh vial and record mass of product.
• 11. Obtain IR spectrum of product.