10.2d Specific about alcohols

 1. Combustion reaction: Alcohol burns in O₂ (oxygen gas) to produce CO₂ and H₂O. Don’t forget to balance the equation.

 CH₃OH + ³/₂ O₂ → CO₂ + 2 H₂O

Or

2 CH₃OH + 3 O₂ → 2 CO₂ + 4 H₂O

2. Alcohols undergo nucleophilic substitution reactions with acids (also called esterification or condensation)

 3. Redox reactions

 Primary alcohol can be oxidized in two steps. First step produces aldehyde. Second step produces carboxylic acid

Secondary alcohol can be oxidized only once to produce a keytone

​

Tertiary alcohol cannot be oxidized 

​

During the oxidation, the orange dichromate ion is reduced to the green Cr³⁺ ion. This can be used to detect alcohols.

How to distinguish or to isolate the different types of alcohol?

Step 1: Add the alcohol to potassium dichromate(VI) solution acidified with dilute sulphuric acid. The tube would be warmed in a hot water bath.

Step 2: Isolate  aldehyde and carboxylic acid using distillation and reflux