See image — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

Concept: DDT (Dichlorodiphenyltrichloroethane) is synthesized by the condensation of chlorobenzene with chloral (trichloroacetaldehyde, CCl3CHO) in the presence of concentrated sulphuric acid as a catalyst. Step 1: Identify the reagents. Chlorobenzene (C6H5Cl) is an aromatic compound, and chloral (CCl3CHO) is trichloroacetaldehyde. Step 2: Reaction mechanism. In the presence of concentrated H2SO4, chloral acts as an electrophile (or is activated to form a carbocation intermediate). Two molecules of chlorobenzene react with one molecule of chloral in a Friedel-Crafts type (electrophilic aromatic substitution) condensation reaction. Step 3: Product formation. The reaction produces 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane, which is DDT. The para positions of two chlorobenzene rings are substituted by the CHCCl3 group, forming the well-known insecticide DDT. Step 4: Elimination of other options. - Freon: Freon compounds are chlorofluorocarbons (CFCs) made from hydrocarbons, not from chlorobenzene and chloral. - Gammexene: Gammexene (BHC/lindane) is made by the addition of chlorine to benzene under UV light, not involving chloral. - Hexachloroethane: This is C2Cl6, formed by chlorination of ethane, not from chlorobenzene and chloral. Therefore, the correct answer is B.