GB627263A - Improvements in or relating to 1, 1, 2-trichlorethane and process of preparing the same - Google Patents

Abstract

1,1,2-Trichloroethane is prepared by adding one molecular proportion of chlorine to slightly more than one molecular proportion of vinyl chloride (e.g. 1.02 to 1.1 mols.) in the dark in the presence of at least 20 molecular proportions of 1,1,2-trichloroethane at a temperature of 20 DEG to 60 DEG C. and in the absence of any catalyst. It is desirable to mix the chlorine with the vinyl chloride at the point of introduction in the trichloroethane. Inert gases such as oxygen, hydrogen or nitrogen may be present and the process may be carried out either as a batch operation or in a continuous manner. In the latter case the flow of trichloroethane is preferably counter-current to the flow of reagent gases, thus the trichloroethane may be introduced at the top of a gasabsorption tower and the mixture of vinyl chloride and chlorine near the middle or bottom of the tower which may be packed with Raschig rings, coke or activated carbon. The product may be recirculated after cooling and in both the batch and continuous processes the product may be purified by washing with a dilute aqueous alkaline solution, and then dried by centrifuging or with a chemical drying agent, e.g. calcium chloride. Alternatively, the product may be distilled directly. In an example of the batch process a mixture of vinyl chloride and chlorine are introduced into 1,1,2-trichloroethane at 20 DEG C. and the temperature rises to 40 DEG to 50 DEG C. The product is washed with dilute aqueous sodium bicarbonate solution and then distilled. Specification 341,781 and U.S.A. Specifications 1,833,358, 1,833,393, and 1,944,306 are referred to. The Specification as open to inspection under Sect. 91 is not restricted to the use of the specified molecular proportions of chlorine and vinyl chloride. This subject-matter does not appear in the Specification as accepted.