Why benzyl alcohol is not converted directly to phenylethanoic acid on oxidation
Oxidation of alcohol first forms an aldehyde and then carboxylic acid.Both aldehyde and carboxylic acid contains the same number of carbon atoms. Benzyl alcohol on oxidation forms an aldehyde and then benzoic acid. Phenylethanoic acid has one additional carbon atom as compared to benzyl alcohol. Hence benzyl alcohol is not converted directly to phenylethanoic acid on oxidation. It requires addition of cyanide group which would increase the number of carbon atom on the ring.