Identify the intermediate in the halogenation of alkanes. a) Anionb) Cationc) Radicald) Dimer

Answer: Option C - Radical

Explanation:

A radical is a chemical specie carrying a lone electron. In the halogenation of alkanes: take Methane CH4 as the alkane, and Chlorine Cl as the halogen.

The step by step halogenation process is as follows:

CH4 + Cl2 - -> CH3• + HCl + Cl•

CH3• + Cl2 - -> CH3Cl + HCl

CH3Cl + Cl2 - -> CH2Cl2 + HCl + Cl•

CH2Cl2 + Cl2 - -> CHCl3 + HCl

CHCl3 + Cl2 - -> CCl4 + HCl + Cl•

Chlorine molecule attack methane knocking off an hydrogen atom from it and forming a methyl radical (CH3•), that is subsequently attack by another chlorine molecule. This cycle repeats itself, until no hydrogen atom is available for substitution by the highly reactive chlorine radical.

Note: no cation or anion is formed in the halogenation process