Chapter 23, Problem 97IL

Interpretation Introduction

Interpretation:

Identification of the given liquid is to be done and the chemical equation has to be written.

Concept introduction:

The given liquid can be either benzene or cyclohexene. The reaction of bromine vapour with an alkene gives decolorisation of bromine vapours. This reaction is used for the test of unsaturation or double bond in hydrocarbons.

Bromination of alkenes:

Alkene undergoes bromination which yields the dibromo compound (vicinal dibromides or 1,2-dibromides).

Benzene does not react with bromine vapours. However, it undergoes electrophilic substitution reaction with halogens in presence of a lewis acid such as ${\text{FeBr}}_{\text{3}}$, ${\text{AlCl}}_{\text{3}}$ etc. Therefore, benzene react with halogens in precise or strict reaction conditions.