Question

Why carboxylic acid do not give the characteristic reaction of carbonyl group?

Answer 1

In carboxylic acid one H atom is directly attached to O atom unlike other carbonyl compounds in which all the H are attached to the C atoms.O-H bond is more polar than C-H bond, and thus carboxylic acids are more acidic than other carbonyl compounds. This gives some chemical properties to the carboxylic acid which other carbonyl compounds do not have and carboxylic acid do not give the characteristic reaction of carbonyl group.