Question

Why is the oxidation of a primary alcohol witha mixture of sodium dichromate and sulphuric acid not a good method for the preparation of corresponding aldehyde?

• A. The product will be the corresponding ketone
• B. Any aldehyde produced will be oxidised further
• C. The product will be an alkyl sulphonate, $R-S O_{3}H$ mixture of sodium dichromate and sulphuric acid will not oxidize a primary alcohol
• D. A mixture of sodium dichromate and sulphuric acid will not oxidised a primary alcohol

Answer 1

Answer: (B)

Primary alcohols can be oxidized to either aldehydes or carboxylic acids depending on the reaction conditions. In the case of the formation of carboxylic acids, the alcohol is first oxidized to an aldehyde which is then oxidized further to the acid.

$Primary \, Alcohol \, \overset{\left[O\right]}{ \rightarrow } \, Aldehyde \, \overset{\left[O\right]}{ \rightarrow }Carboxylicacid$

So, any aldehyde produced will be oxidized further during the reaction.