Carboxylic acids do not give the characteristic reactions of carbonyl group. Explain.

Explanation

In general, carboxylic acids can be represented as follows :

Despite the presence of and -OH groups, carboxylic acids fail to give characteristic reactions of carbonyl group such as reactions with ammonia derivatives (hydrazine, hydroxylamine etc.) and other nucleophilic addition reactions. Similarly carboxylic acids fail to give certain reactions of alcoholic group such as reaction with halogen acids. This can be explained on the basis of resonance as follows :

Due to resonance the carboxylic carbon is less electrophilic than carboxylic carbon and as such carboxylic acids fail to give common nucleophilic addition reactions of aldehydes and ketones.