See image — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the starting material: The starting material is 2-benzylbenzoic acid (a benzoic acid with a benzyl group, -CH2C6H5, at the ortho position). Step 2 - Reaction with SOCl2 to give A: SOCl2 converts the carboxylic acid (-COOH) to an acid chloride (-COCl). So A is 2-benzylbenzoyl chloride (ortho-benzylbenzoyl chloride). Step 3 - Reaction with AlCl3 (Friedel-Crafts acylation) then H3O+ to give B: The acid chloride undergoes intramolecular Friedel-Crafts acylation. The acyl chloride group attacks the pendant benzyl phenyl ring (the C6H5 of the CH2C6H5 group) in an intramolecular fashion. This forms a six-membered ring ketone by cyclization. The product B is a cyclic ketone: specifically, the acylium ion attacks the ortho position of the pendant phenyl ring, forming a new C-C bond and creating a 6-membered ring ketone fused to two benzene rings. This product is anthracen-10(9H)-one (anthrone) or more precisely 9(10H)-anthracenone — a tricyclic system with a ketone. Actually, the intramolecular Friedel-Crafts gives a six-membered ring containing C=O between two aryl groups: this is anthrone (9-anthracenone), where there is a CH2 at position 10 and C=O at position 9. Wait — let me reconsider. The starting acid chloride is Ar-COCl with Ar bearing a -CH2-Ph group ortho. Intramolecular Friedel-Crafts: the COCl acylates the pendant Ph ring to form a 6-membered ring: Ar-CO-[ring closure to CH2-Ph], giving a ketone bridging the two arene units. The product is 9-anthracenone (anthrone): a central 6-membered ring with C=O at C9 and CH2 at C10, fused to two benzene rings. So B = anthrone. Step 4 - Clemmensen reduction (Zn-Hg, conc. HCl, heat) of B to give C: Clemmensen reduction reduces a ketone (C=O) to a methylene (CH2). So the C=O in anthrone (B) is reduced to CH2, giving 9,10-dihydroanthracene. This is a molecule with two benzene rings connected by a -CH2-CH2- bridge, which is exactly option (d). Why other options fail: - (a) is a lactone product, which would arise from a different reaction pathway (not Friedel-Crafts + Clemmensen). - (b) is a benzofuran derivative, requiring oxygen incorporation that doesn't occur here. - (c) is anthrone (B itself), not the final reduced product C. - (d) 9,10-dihydroanthracene is the correct product after Clemmensen reduction of anthrone. Therefore, the correct answer is D.