Question

How would you prepare diphenylmethane, ${\left(\mathbf{Ph}\right)}_2{\mathbf{CH}}_2$ , from benzene and an acid chloride?

Short answer

Aromatic ring can activate benzylic carbonyl group towards reduction. The reduction of aryl alkyl ketones prepared by Friedelcraft’s acylation gets converted to alkylbenzene by hydrogenation over the palladium catalyst. Aryl alkyl ketone with a nitro substituent gets reduced to an amino group during the process of reduction in the presence of ${\mathrm{H}}_2$/Pd.

Step-by-step solution

Reduction of Aromatic Compounds 

Aromatic ring can activate benzylic carbonyl group towards reduction. The reduction of aryl alkyl ketones prepared by Friedelcraft’s acylation gets converted to alkylbenzene by hydrogenation over the palladium catalyst. Aryl alkyl ketone with a nitro substituent gets reduced to an amino group during the process of reduction in the presence of ${\mathrm{H}}_2$/Pd.

Preparing diphenylmethane from benzene and an acid chloride

Diphenylmethane can be prepared by reducing benzophenone with${\mathrm{H}}_2$ /Pd. Benzophenone can be prepared by reacting benzene with benzoyl chloride in the presence of ${\mathrm{AlCl}}_3$(Friedal-Crafts acylation).The reaction can be given as:

Preparing diphenylmethane from benzene and an acid chloride