The synthesis of 3,4-Dichlorobenzophenone is as follows:In around-bottom flask, diarylmethanes (1.0 mmol), NBS (889.9 mg, 5.0 mmol) andwater (0 or 5.0 mmol) were dissolved in CHCl3 (4.0 mL). After refluxing for 3 h in the air, the reaction mixture was quenched withNa2S2O3·5H2O, cooled to roomtemperature, washed with 5mL CH2Cl2, dried with MgSO4,and filtered to get clear organic solution. The solvent was removed reduced pressure by a rotary evaporator, and the resulting residue was subjected to column chromatography on silica gel using co-solvent(ethyl acetate / petroleum ether, v/v) as eluent to give the corresponding diaryllketones.
