Chapter 12, Problem 20P

Interpretation Introduction

Interpretation:

The mechanism of the given reaction is to be written.

Concept introduction:

The reaction of Grignard reagents with esters yields secondary and tertiary alcohols as their products. These reactions are two-step reactions. In the first step, nucleophilic addition of carbonyl group takes place because Grignard reagent being nucleophilic uses its lone pair of electrons to form a bond with a carbon atom. This results in the formation of an alkoxide ion that remains associated with $M{g}^{2+}$ and $X^{-}$.

In the second step, addition of aqueous HX causes the protonation of the alkoxide ion which leads to the formation of the alcohol and $Mg{X}_2$.

Carbonyl groups of cyclic esters react with 2 equivalents of Grignard reagents and followed by hydrolysis to produce tertiary alcohols.