Chapter 18.7, Problem 13P

Interpretation Introduction

Interpretation: Alkylation of $\alpha$ carbon is more favored when the alkyl halide is primary and not when alkyl halide is tertiary.

Concept introduction: Alkylation of $\alpha$ carbon atom in a carbonyl compound proceeds via the ${\text{S}}_{\text{N}}\text{2}$ mechanism.  The ${\text{S}}_{\text{N}}\text{2}$ reaction involves only one step in which the carbonyl compound and alkyl halide combine to form a transition state.  If the alkyl halide is bulky the transition state cannot be formed due to steric hindrance and instead an elimination product is formed.