See image — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

Step 1: Identify reaction A (Friedel-Crafts alkylation). Benzene (C6H6) reacts with propylene (CH3CH=CH2) in the presence of H3PO4 (acid catalyst) and heat. The acid protonates propylene to give the more stable secondary carbocation (CH3-CH(+)-CH3), which then attacks benzene via electrophilic aromatic substitution. Product A is isopropylbenzene (cumene): C6H5-CH(CH3)2. Step 2: Identify reactions giving B and C (Cumene oxidation process). Cumene (A) is treated with O2 under heat to form cumene hydroperoxide (C6H5-C(CH3)2-OOH). Then treatment with dilute acid (H3O+) and heat causes the Hock rearrangement: the hydroperoxide undergoes acid-catalyzed cleavage to give phenol (C6H5OH) and acetone (CH3COCH3). Step 3: Assign B and C. B = phenol, C = acetone (or vice versa). Step 4: Eliminate incorrect options. (a) Benzaldehyde and acetaldehyde - incorrect; these would require oxidative cleavage of ethylbenzene, not cumene. (b) Benzoic acid and acetic acid - incorrect; these would result from strong oxidation of the side chain, not the cumene hydroperoxide process. (c) Phenol and propionaldehyde - incorrect; propionaldehyde would come from a different substrate (n-propylbenzene oxidation cleavage), not cumene. (d) Phenol and acetone - correct; this is exactly the industrial cumene process. Therefore, the correct answer is D.