Chapter 20, Problem 20.53P

Interpretation Introduction

(a)

Interpretation:

The complete mechanism for the given reaction is to be drawn.

Concept introduction:

Methoxide acts as a good leaving group; the nucleophile attacks the adjacent electropositive carbon. In ${\text{NaSCH}}_{\text{3}}$, ${\text{CH}}_{\text{3}}{\text{S}}^{\text{-}}$ acts as a nucleophile, electron rich site and the C atom of C=O group acts as electron poor site. Electron rich atom attacks the electron poor atom.

Interpretation Introduction

(b)

Interpretation:

Whether the given reaction is energetically favorable or not is to be explained.

Concept introduction:

Size of anion governs the stability of the respective anion. A bigger anion can stabilize the negative charge better compared to a smaller anion.