The correct order of acidity for the following compounds is\

Question

Professor PC Thomas Classes · Answer

(a) : Due to ortho-effect, (I) and (II) are stronger acids than (III) and (IV). Due to two ortho hydroxyl groups in (I), it is stronger acid than (II). (III) is a stronger acid than (IV) because at $m$-position, - OH group cannot exert its $+R$ effect but can only exert its $-I$ effect while at $p$-position, -OH group exerts its strong $+R$ effect.\ Thus, the correct order of acidity is : I $>$ II $>$ III $>$ IV\