Question

Arrange the following carboxylic acids in increasing order of reactivity towards thermal decarboxylation reaction :

• A. I < II < III < IV
• B. I < III < IV < II
• C. I < IV < II < III
• D. IV < I < II < III

Answer 1

The correct option is C I < IV < II < III

The increasing order of reactivity towards thermal decarboxylation reaction for carboxylic acids is $I<IV<II<III$
Greater the stability of carbanion intermediate, greater the reactivity towards decarboxylation. III forms most stable carbanion on loss of $C{O}_2$ and I form least stable carobanion. Carbanion from II is more stable than the carbanion from IV since $-N{O}_2$ is stronger electron withdrawing group than C=O.