Chapter 8, Problem 8.59P

Interpretation Introduction

Interpretation:

A complete, detailed mechanism is to be drawn for the given reaction.

Concept introduction:

One way to synthesize diethyl ether is to heat ethanol in the presence of a strong acid. This is an example of a nucleophilic substitution reaction. In the first step of the mechanism, the strong acid will protonate the OH group in ethanol. This is a proton transfer reaction.

This step is necessary. If nucleophilic substitution were to take place first instead, the leaving group would come off as ${\text{OH}}^{-}$, which is a strong base and is not compatible with the acidic conditions. A proton transfer reaction is handy and can be used in the reaction mechanism so as to avoid generation of non-compatible species that interfere with the reaction medium.