Chapter 8, Problem 8.30P

Interpretation Introduction

Interpretation:

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

Concept introduction:

$\text{E1}$ reaction is a two-step, unimolecular elimination reaction. In the first step of heterolysis, the carbon-halogen bond breaks to yield a carbocation intermediate. It is also the slow, rate-determining step. The second step is deprotonation from an adjacent carbon that leads to the formation of a $\text{π}$ bond.

The carbocation initially formed in the first step may rearrange if the rearrangement leads to a more stable carbocation. This can occur via two processes. One process is resonance stabilization if the carbocation is one bond away from the $\text{π}$ bond or an electron-rich atom like oxygen. The second process of rearrangement is a $\text{1, 2-hydride}$ or $\text{1, 2-methyl}$ shift.