Chapter 17, Problem 17.5P

Interpretation Introduction

Interpretation:

The major organic product of the given reaction is to be predicted.

Concept introduction:

${\text{LiAlH}}_{\text{4}}$ is a strong reducing agent and a source of ${\text{H}}^{\text{-}}$. It can be used to convert a ketone to an alcohol. In this reaction, step 1 involves the nucleophilic addition of ${\text{H}}^{\text{-}}$ to the carbonyl group to produce the strongly basic alkoxide anion. In step 2, ${\text{NH}}_{\text{4}}\text{Cl}$ protonates the alkoxide anion to produce the final product, an alcohol. To avoid destroying ${\text{LiAlH}}_{\text{4}}$, ${\text{NH}}_{\text{4}}\text{Cl}$ is added in step 2 instead of step 1. The reaction with ${\text{LiAlH}}_{\text{4}}$ occurs in ether, which is not acidic, so the proton transfer in step 2 does not occur until the acid is added separately.