Chapter 18, Problem 18.71P

Interpretation Introduction

Interpretation:

The detailed mechanism for the given reaction of benzaldehyde with propenenitrile in presence of a catalytic amount of $\text{NaCN}$ is to be drawn.

Concept introduction:

The aromatic aldehyde can be converted to a good nucleophile as carbanion by reacting it with catalytic cyanide ion. The carbanion undergoes nucleophilic addition reaction with polar $\text{π}$ bond or conjugated polar $\text{π}$ bond like conjugated nitrile. In the first step, the cyanide ion undergoes nucleophilic addition with aromatic aldehyde and forms a cyanohydrin. The cyanohydrin in presence of base like hydroxide ion forms a resonance stabilized carbanion, which further adds to conjugated nitrile and forms an intermediate by proton transfer. The intermediate formed then undergoes elimination of cyanide forming carbonyl derivative having cyanide functional group.