Chapter 12, Problem 12.35P

Interpretation Introduction

Interpretation:

The reason for the given order of relative reaction rates of electrophilic addition of ${\text{Br}}_{\text{2}}$ to several alkenes is to be explained.

Concept introduction:

Molecular bromine undergoes anti addition across a $\text{C=C}$ double bond. As the electron-rich alkene approaches ${\text{Br}}_{\text{2}}$ molecule, it temporarily generates an electron-poor site on the Br atom closer to the alkene. The subsequent flow of electrons takes place between the electron-rich alkene and the electron-poor Br atom. The presence of an electron donating group attached to the $\text{C=C}$ double bond makes it more electron rich which can increase the driving force for the electrophilic addition step.