Identify the compounds A, B, C and D. 1,2,2,2-tetrachloroethane [ ] Zn [ A ] [A] [675 ~K ] Fe tube [B] [ Conc. H ₂ SO ₄] Conc. HNO ₃ [C] [ Anhydrous AlCl ₃] Cl / [D]

Step-by-step solution

The reaction sequence is as follows: 1. Dehalogenation of 1,1,2,2-tetrachloroethane with Zn dust: CHCl₂ -CHCl₂ + 2Zn CH CH + 2ZnCl₂ . Thus, [A] is C₂ H₂ (acetylene). 2. Cyclic polymerization of acetylene: 3C₂ H₂ [675 K ] Fe tube C₆ H₆ (benzene). Thus, [B] is benzene. 3. Nitration of benzene: C₆ H₆ + HNO₃ (conc.) H ₂ SO ₄ (conc.) C₆ H₅ NO₂ (nitrobenzene). Thus, [C] is nitrobenzene. 4. Chlorination of nitrobenzene: Nitrobenzene is a meta-directing group due to the strong electron-withdrawing effect of the -NO₂ group.