Chapter 8, Problem 8.51P

Interpretation Introduction

Interpretation:

Whether the given nucleophilic substitution reaction proceeds by ${\text{S}}_{\text{N}}\text{1}$ mechanism or ${\text{S}}_{\text{N}}\text{2}$ mechanism is to be determined on the basis of the graph of the optical rotation as a function of time.

Concept introduction:

A ${\text{S}}_{\text{N}}\text{1}$ mechanism is a two-step mechanism that proceeds through a carbocation intermediate. This results in the formation of a mixture of isomers. A ${\text{S}}_{\text{N}}\text{2}$ mechanism is a one-step mechanism that results in the inversion of symmetry at the reaction center and produces a single isomer.

Progress of a reaction involving optically active reactant and/or product can be monitored by measuring the optical rotation as a function of time.