Name: Nomenclature of Haloalkanes and Haloarenes
Uploaded: 2019-07-19
Duration: 9 min 1 s
Description: Haloalkanes are formed by replacing a hydrogen atom in an alkane with a halogen atom. Haloarenes are derived by replacing the hydrogen atom attached to the b...

Question

Describe the preparation and properties of chlorobenzene.

Accepted Answer

Preparation of chlorobenzene:

Chlorobenzene is prepared commercially by the Raschig process. In this process, a mixture of benzene vapours, air and hydrogen chloride is passed over heated cupric chloride to produce chlorobenzene.

$2 C_{6} H_{6} + 2 HCl + O_{2} \overset{{CuCl}_{2} + ∆}{\to} 2 C_{6} H_{5} Cl + 2 H_{2} O$

Properties of chlorobenzene:

1. Chlorobenzene undergoes nucleophilic substitution reactions. For example: The preparation of phenol from chlorobenzene. The reaction takes place in 2 steps. In the first step a carbanion is formed by the nucleophilic attack of ${OH}^{-}$ on the carbon carrying the chlorine. This is slow and rate determining step. In the second step which is fast, the halogen leaves the carbanion and phenol is formed.

2. Chlorobenzene undergoes electrophilic substitution reactions such as halogenation, nitration, sulphonation and Friedel-Craft reactions. As chlorine is ortho and para directing, substitution reaction occurs at these positions.

Describe the preparation and properties of chlorobenzene.

Important Questions on Haloarenes (Aryl Halides)

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