Question

(a) Account for the following:
(i) $C{H}_{3}CHO$ is more reactive than $C{H}_{3}COC{H}_3$ towards reaction with $HCN$.
(ii) Carboxylic acid is a stronger acid than phenol.
(b) Write the chemical equations to illustrate the following name reactions:
(i) Wolff-Kishner reduction
(ii) Aldol condensation
(iii) Cannizzaro reaction

Answer 1

(a) - (i) The methyl group due to its +I effect reduce the magnitude of positive charge on carbonyl carbon atom. Moreover, it also hinders the approach of nucleophile $C{N}^{-}$. Since, in acetaldehyde there is one methyl while in acetone there are two methyl groups attached to crbonyl group therefore acetaldehyde is more reactive than acetone towards nucleophilic addition with HCN.

(ii) Because the release of proton from carboxylic acid is much easier than from phenol as the conjugate base. Carboxylate ion is much more resonance stabilised than conjugate base phenoxide ion.

(b)- (i) Ref. image (ii) Ref. image (iii) Ref. image