See image — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

Step 1: Reaction of Pyrrole with PhMgBr. Pyrrole has an acidic N-H (pKa ~17). PhMgBr acts as a base (PhH pKa ~43 — actually benzene pKa ~43 but the Grignard acts as a strong base). PhMgBr deprotonates the N-H of pyrrole to give the pyrrolyl magnesium bromide salt (pyrrole-N-MgBr, structure 3) as product E, and releases benzene (PhH, structure 2) as product F. So E = 3 (pyrrolyl-MgBr, the Grignard reagent of pyrrole at nitrogen) and F = 2 (benzene). Step 2: Confirm F + MeCl → no reaction without catalyst. Benzene (F = 2) does not react with MeCl (methyl chloride) without a Lewis acid catalyst (Friedel-Crafts conditions require AlCl3). This is consistent with the problem statement. ✓ Step 3: E + MeCl → G + H. E = pyrrolyl-MgBr (structure 3) reacts with MeCl. The pyrrolyl anion is ambident: it can alkylate at N or at C. For pyrrole Grignard with alkyl halides, C-alkylation is preferred at the 2-position (most nucleophilic carbon), giving 2-methylpyrrole (structure 6) as G. The other product H is MgBrCl (an inorganic salt), but among the given numbered structures, H must correspond to a numbered organic structure. Wait — re-examining: when pyrrolyl-MgBr reacts with MeCl, the main organic products would be either N-methylpyrrole or C-methylpyrrole. However, N-methylpyrrole is not among the listed structures (structures 6 and 7 are 2-Me and 3-Me pyrroles, both with N-H). The reaction of pyrrolyl Grignard with MeCl gives predominantly C-alkylation: 2-methylpyrrole (G = 6) and the minor product 3-methylpyrrole (H = 7), along with MgBrCl as byproduct. So E = 3, F = 2, G = 6, H = 7 → answer (a) 3, 2, 6, 7. Step 4: Why other options fail. (b) 4, 5, 6, 1: E=4 (2-phenylpyrrole) is wrong; PhMgBr cannot do C-phenylation of pyrrole without transition metal catalyst under normal conditions. Also F=5 and H=1 don't fit. (c) 3, 4, 5, 2: F=4 is wrong; benzene should be the byproduct of deprotonation, not 2-phenylpyrrole. (d) 3, 2, 4, 5: G=4 (2-phenylpyrrole) and H=5 are wrong; MeCl would give methyl substitution, not phenyl substitution. Therefore, the correct answer is A.