Question

Convert : (a) Benzene into benzaldehyde, (b) Cyclohexene into adipic acid.

Hint:

Adipic acid is a precursor for Nylon-6,6. Its green synthesis often uses cyclohexene and hydrogen peroxide.

Answer 1

Step 1: Understanding the Concept:
(a) Involves formylation of an aromatic ring.
(b) Involves strong oxidation and ring opening of an alkene.
Step 2: Detailed Explanation:
(a) Benzene to Benzaldehyde:
Benzene is treated with Carbon monoxide (\(CO\)) and Hydrogen chloride (\(HCl\)) in the presence of anhydrous Aluminium chloride (\(AlCl_3\)) and Cuprous chloride (\(CuCl\)).
Reaction: \( C_6H_6 + CO + HCl \xrightarrow{AlCl_3/CuCl} C_6H_5CHO + HCl \)

(b) Cyclohexene to Adipic acid:
Cyclohexene undergoes oxidative cleavage when treated with hot, acidified Potassium permanganate (\(KMnO_4/H^+\)). The double bond breaks and terminal carbons are oxidized to carboxylic acids.
Reaction: \( C_6H_{10} \xrightarrow{KMnO_4, \Delta, H^+} HOOC-(CH_2)_4-COOH \)
Step 3: Final Answer:
(a) Use Gattermann-Koch reaction. (b) Use oxidative cleavage with hot acidic \(KMnO_4\).