GB1056522A - Manufacture of chlorinated ethanes - Google Patents

Abstract

1,056,522. Chlorinated ethanes. IMPERIAL CHEMICAL INDUSTRIES Ltd. March 31, 1964 [Feb. 10, 1964], No. 5436/64. Heading C2C. Tetrachloroethanes and / or 1,1,2 - trichloroethane, in any desired proportion, are produced by establishing an equilibrium in a continuous system comprising a packed reaction column surmounted by a reflux condenser by (1) feeding ethylene into the base of the column and chlorine into the column between the ethylene feed point and the head of the column in the absence of light; (2) passing down the column a recycle liquor consisting of (i) 1,2-dichloroethane alone when 1,1,2-trichloroethane is required as product; or (ii) 1,2-dichloroethane and 1,1,2-trichloroethane when tetrachloroethanes are required as or in the product; the whole of the 1,2-dichloroethane in the products leaving the base of the column being recovered and recycled to the reaction column, and, in case (ii) above, a part or the whole of the 1,1,2-trichloroethane being similarly recovered and recycled; (3) maintaining the column at, at least 50‹ C. but not above the boiling point of the liquor fed in at the head of the column; (4) feeding into the head of the column additional 1,2-dichloroethane from a source outside the system, so that this, together with recycled liquor, gives a combined recycle liquor containing at least 5 mole per cent of 1,2-dichloroethane; (5) utilizing chlorine, in the presence of absence of oxygen, and such molar ratios of chlorine to ethylene that there is a net loss of 1,2-dichloroethane made in the system thus necessitating addition of 1,2 - dichloroethane from an external source, and so that 1 mole of 1,1,2-trichloroethane and/or tetrachloroethanes is produced per total of 1 mole of ethylene and 1,2-dichloroethane reacted; (6) withdrawing HCI from the condenser surmounting the column; and (7) recovering from the liquor leaving the base of the reaction column that portion of chlorinated ethanes which is not recycled to the reaction column and which is the desired product. To obtain a product consisting essentially of tetrachloroethanes when using chlorine free from oxygen the proportion of 1,2-dichloroethane in the combined recycle liquor should be greater than 20 mole per cent, e.g. 21À5 mole per cent, the remainder being 1,1,2-trichloroethane, with a molar ratio of chlorine to ethylene of 3-7 : 1. As the proportion of 1,2-dichloroethane in the combined recycle liquor is increased, the proportion of 1,1,2-trichloroethane in the product increases and may be obtained at any desired level accordingly. Unreacted ethylene may be recovered and re-used, or chlorinated or oxychlorinated, using, e.g. the HCl produced, to form 1,2- dichloroethane which may be fed to the column. If chlorine containing oxygen is used in the process of the invention, the ratios given above are adjusted.