GB768904A - Process for preparing 1, 1, 2-trichlorethane - Google Patents

Abstract

1,1,2-Trichlorethane is prepared by reacting 1,2-dichlorethylene with hydrogen chloride, the reaction being started under a partial pressure of hydrogen chloride between about 5 and 50 atmospheres gauge at between about 50 DEG and about 110 DEG C. and in the presence of aluminium chloride. The reaction is preferably started at between about 50 DEG C. and 70 DEG C. at between about 10 and 20 atmospheres gauge and is preferably finished at between about 50 DEG and 110 DEG C. under a pressure between atmospheric and a partial pressure of hydrogen chloride of about 40 atmospheres gauge. The preferred quantity of aluminium chloride catalyst is in the range of 0.2 to 5 per cent referred to the trichlorethane formed. The starting materials are advantageously dried before use and the process may be continuous or discontinuous. The hydrogen chloride can be diluted with gases indifferent to the reaction. In examples: (1) hydrogen chloride is introduced at 30 atmospheres gauge into 1,2-dichlorethylene containing aluminium chloride in an autoclave, which is then heated to 60 DEG C., when the pressure rises to 40-50 atmospheres. At 60-70 DEG C. the pressure drops to atmospheric. Heating is continued to 90 DEG C. and hydrogen chloride is continuously added at normal pressure until absorption ceases. After cooling, the reaction product is recovered by distillation. (2) The initial stages are as in Example (1) but when the pressure starts to drop at 60 DEG C. it is maintained at 25-30 atmospheres at 85-90 DEG C. by the continuous introduction of hydrogen chloride. A higher yield of trichlorethane is thus obtained.