(a) How will you prepare the following compounds starting with benzene:(i) Benzaldehyde(ii) Acetophenone

(i) Preparation of Benzaldehyde from Benzene:

1. Nitration: Benzene is first nitrated by using a mixture of concentrated nitric acid and concentrated sulphuric acid. This forms nitrobenzene.

2. Reduction: Nitrobenzene is then reduced to phenylamine (aniline) by using tin and hydrochloric acid.

3. Diazo Coupling: Phenylamine is then diazotized in the presence of nitrous acid (prepared in situ from sodium nitrite and hydrochloric acid) at 0-5°C to form diazonium salt.

4. Sandmeyer Reaction: The diazonium salt is then treated with copper powder and hydrochloric acid to form chlorobenzene.

5. Oxidation: Finally, chlorobenzene is oxidized by using air in the presence of sunlight to form benzaldehyde.

(ii) Preparation of Acetophenone from Benzene:

1. Friedel-Crafts Acylation: Benzene is treated with acetyl chloride (CH3COCl) in the presence of anhydrous aluminum chloride (AlCl3) as a catalyst. This results in the substitution of a hydrogen atom in benzene with the acetyl group, forming acetophenone.