Chapter 6, Problem 26P

Interpretation Introduction

Interpretation:

Out of the three alkyl halides given, the one that is most reactive towards potassium iodide in acetone is to be determined and the reason is to be explained. The two isomers that differ in reactivity by a factor of two are to be determined, and the one which is more reactive out of them is to be determined. The reason for the higher reactivity of that isomer is to be explained.

Concept introduction:

In a ${\text{S}}_{\text{N}}{}^2$ reaction, the attack of the nucleophile on the alkyl halide takes place from the side opposite to the bond by which the leaving group is attached. This attack is sterically hindered by alkyl substituents that are attached to the carbon atom that is being attacked.

In general, ${\text{S}}_{\text{N}}{}^2$ reactions of alkyl halides show the following dependence of rate on structure: $\text{primary > secondary > tertiary}$