[OH-].[Na+].[Cl:3][C:4]1[CH:9]=[CH:8][C:7]([Cl:10])=[CH:6][CH:5]=1.[C:11](Cl)(=[O:18])[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1.[Cl-].[Al+3].[Cl-].[Cl-]>O>[Cl:3][C:4]1[CH:9]=[CH:8][C:7]([Cl:10])=[CH:6][C:5]=1[C:11]([C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1)=[O:18]To a 22 L, three-necked flask fitted with a thermometer, mechanical stirrer and a Vigreux column connected to an aqueous NaOH scrubbing tower, was added 1,4-dichlorobenzene (3 Kg, 26.4 mol) and benzoyl chloride (2.6 Kg, 18.55 mol). The mixture was heated to 80° C. to give a homogeneous solution. Aluminum chloride (5.5 Kg, 41.25 mol) was added over 12 min. with stirring. (The molar ratio of reactants was 2.2:1.4:1.0 (AlCl3 : Dichlorobenzene:Benzoyl Chloride)). The resulting mixture was heated to 140° C. over 60 min followed by heating to 175° C. over 30 min. Heating was stopped at 175° C. The mixture was allowed to cool to 80° C. over two hours and poured into a well stirred mixture of ice and water (ca. 25 L water and 15 Kg of ice) over 30 min. The organic solid was collected by filtration and dissolved in 7 L of toluene. The solution was washed with aqueous sodium bicarbonate and dried. Toluene was removed by distillation. Pure 2,5-dichlorobenzophenone was isolated in 80% yield after recrystallization from hexane and toluene. Gas chromatography indicated an absolute yield of 97%.
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