GB604579A - Production of polyhaloacyl halides - Google Patents

Abstract

Polyhalogenated, straight - chain aliphatic carboxylic acid halides are produced by heating at a temperature of 50 DEG C. to 250 DEG C. and under superatmospheric pressure a substantially anhydrous mixture of carbon monoxide and a polyhalogenated ethane containing from 3 to 5 halogen atoms in the presence of a Friedel-Crafts catalyst which is a halide of a polyvalent inorganic element, e.g. aluminium-chloride, bromide, or fluoride; ferric chloride, zinc chloride, titanium chloride and boron trifluoride. It is preferable to employ a polychlorinated ethane containing from 3 to 5 chlorine atoms and to employ reaction temperatures of between 70 DEG C. and 200 DEG C. and a pressure range of 50 to 1000 atmospheres. In examples: (1) carbon monoxide is added to a mixture of pentachloroethane and anhydrous aluminium chloride in a pressure vessel which is then heated, additional carbon monoxide being added to maintain a pressure of 950 atmospheres. The vessel is then cooled, the pressure slowly released and the volatile materials removed from the catalyst under reduced pressure. Fractionation of the product yields tetrachloropropionyl chloride with some tetrachloroethylene; (2) and (3) beta-trichloroethane and symmetrical tetra-chloroethane respectively are reacted with carbon monoxide in the presence of aluminium chloride as in (1) dichloropropionyl chloride and dichloroacrylyl chloride being respectively obtained. A small amount of trichloropropionyl chloride is also obtained in (3). The analogous fluoro- and bromo-ethanes may also be employed. The products are readily convertible to the corresponding acids and other simple derivatives which are useful as pesticides, rubber chemicals, dye intermediates, medicinals and as speciality acids in the leather, metal and electroplating industries.