Chapter 13, Problem 13.15P

Interpretation Introduction

Interpretation:

The nucleophile and the protic solvent that can be used for the forward reaction corresponding to the transform shown are to the determined.

Concept introduction:

Retrosynthesis involves thinking in reverse. The analysis starts with the product and determines the precursor or starting compound that can be used to make the product. In effect, it is an attempt to undo the forward reaction step in the actual synthesis. The precise reactant and reaction conditions are determined later.

If a nucleophilic substitution is required to carry out the step in the forward direction, the exact mechanism and conditions are determined on the basis of the nature of the precursor. Generally primary and in some cases, secondary alkyl halides require an ${\text{S}}_{\text{N}}\text{2}$ reaction. Secondary alkyl halides with good leaving groups and tertiary alkyl halides generally undergo ${\text{S}}_{\text{N}}1$ reaction.

${\text{S}}_{\text{N}}\text{2}$ reactions are generally favored by strong nucleophiles and polar aprotic solvents. ${\text{S}}_{\text{N}}1$ reactions are favored by weak nucleophiles and polar protic solvents.