Chapter 20, Problem 20.14P

Interpretation Introduction

Interpretation:

Detailed mechanism for a generic reaction that converts an acid derivative to a primary alcohol is to be proposed.

Concept introduction:

Hydride ions from sources such as ${\text{NaBH}}_{\text{4}}$ and ${\text{LiAlH}}_{\text{4}}$ are excellent nucleophiles but not practical leaving groups. These kinds of nucleophiles can still react with acid derivatives in nucleophilic addition-elimination reactions and produce aldehyde intermediates.

In the next step, the aldehyde reacts with another equivalent of hydride to produce an alkoxide anion. This alkoxide ion will be protonated by proton transfer from the ethanol. Primary alcohol will be formed.