Question

Why do carboxylic acids not give the characterstic reaction of a carbonyl group

Answer 1

Carbon of Carboxylic group or carbonyl group is electron deficient hence attracts nucleophile. Once the nucleophile attacks the Carbonyl group, the carbon becomes sp3 hybridised and the oxygen takes negative charge. This negative oxygen takes the electrophile to complete the addition reaction. Whereas in carboxylic group, after the attack of nucleophile the OH or G of derivatives of Carboxylic acids behave as good leaving group and escape before the attack of electrophile on negative oxygen.