Chapter 17, Problem 17.66P

Interpretation Introduction

Interpretation: A stepwise mechanism for the acid catalyzed isomerization of $\left(R\right)\text{-carvone}$ to carvacrol is to be drawn and the reason for isomerization is to be explained.

Concept introduction: The $\left(R\right)\text{-carvone}$ involves conjugated enone and non-conjugated alkene. The conversion of $\left(R\right)\text{-carvone}$ to carvacrol is facilitated by four steps. The first step is protonation of non-conjugated alkene to form first tertiary carbocation. The second step is $\text{1, 2-H}\text{shift}$ (carbocation rearrangement) to form second tertiary carbocation. The third step step is abstraction of proiton by base to form conjugated alkene, and the fourth step is enolization to yield desired product.