To 2.5 g (0.06 mole) of 60% commercial sodium hydride was added 50 ml of sieve-dried dimethylsulfoxide. The stirring mixture was heated until evolution of hydrogen gas ceased. The mixture was cooled in an ice-box and 21.4 g (0.06 mole) of (methyl)triphenylphosphonium bromide, a Wittig reagent, dissolved in 60 ml of sieve-dried dimethylsulfoxide, was added in a few minutes. The resulting mixture was stirred for 15 minutes at room temperature. Then, 9 g (0.03 mole) of 2,4'-dichloro-4-nitrobenzophenone was added as a solid. The resulting mixture was heated at 75°-80° under nitrogen overnight. The reaction mixture was diluted with 200 ml of water and extracted with ether. The ethereal extract was dried over magnesium sulfate. The extract was evaporated to dryness. The residue was dissolved in 30 ml of methylene chloride and the solution put through a silica gel column (5.5×21 cm) with an eluant of methylene chloride/n-hexane. The selected fractions were combined and evaporated to give 2.35 g of 1-(4-chlorophenyl)-1-(2-chloro-4-nitrophenyl)ethylene.
