Process for preparing trichloroethylene

摘要

A process for preparing trichloroethylene by chlorinating 1,2-dichloroethane in the liquid phase in the presence of ethylene followed by pyrolytic chlorination or dehydrochlorination of the reaction product. The 1,2-dichloroethane is chlorinated in the liquid phase in a bubble column reactor in the presence of 1 - 10 mole percent of ethylene with a chlorine/1.2-dichloroethane feed ratio of about 0.7 - 1.4/1, a temperature of about 40 DEG to 150 DEG C with superficial velocities exceeding 8 cm/sec. and gas dwell times of about 0.3 to 10 seconds. The chlorinated product is reacted in the gas phase with recirculated tetrachloroethanes and about 20 - 70 moles of chlorine per 100 moles of chlorinated hydrocarbons at temperatures of about 380 DEG to 500 DEG C and dwell times of about 20 to 30 seconds. This gas phase reaction product is separated by distillation into a low-boiling fraction containing predominantly dichloroethylenes and a high boiling fraction containing predominantly trichloroethylene. The low boiling fraction is reacted in the liquid phase with equimolar amounts of chlorine at temperatures of about 60 DEG - 150 DEG C to obtain the tetrachloroethanes that are recirculated. The high boiling fraction is then separated by distillation into the trichloroethylene product and higher boiling point side products.