GB635013A - A process for the production of halogenated hydrocarbons - Google Patents

Abstract

Mono-halogen alkenes and mono-halogen alkanes having the same number of carbon atoms are obtained from the corresponding alkene and either chlorine, bromine or iodine by reacting at 200 DEG to 700 DEG C. and 1-7 atmos. pressure at least two mols. of alkene with one mol. of halogen to produce by halo-substitution the mono-halogen alkene, and reacting the mixture thus obtained at between room temperature and 300 DEG C. and pressures of 1-70 atmos. in the presence of halides or oxyhalides of zinc, aluminium, bismuth, antimony, iron or vanadium to produce the mono-halogen alkane by addition of the hydrogen halide formed in the substitution process to the excess alkene. The substitution product may be removed after either the first or second stages. Products are preferably separated from the reaction mixture by solvent extraction, the preferred solvent being high boiling halogenated hydrocarbons obtained as by-products from the process. Alkenes instanced are normally gaseous olefines or hydrocarbon mixtures containing them, e.g. ethylene, propylene and butene &c. Thus ethylene is reacted with chlorine, preferably in a mol. ratio between 5 : 1 and 6 : 1 at e.g. 350 DEG to 550 DEG C., preferably 425-450 DEG C., under pressures of up to 7 atmos. to produce vinyl and hydrogen chlorides with a minimum of by-products, the effluence is passed to a second reactor where the excess ethylene and hydrogen chloride react at preferably 150 DEG to 250 DEG C., with a pressure of up to 70 atmos. and in the presence of one of the above catalysts optionally on a porous support and with a promoter such as a halide, preferably a chloride, of copper, lithium, antimony, magnesium, calcium and bismuth to produce ethyl chloride which is separated together with vinyl chloride by solvent extraction with e.g. ethylene dichloride which may be formed in the reaction. In an example ethylene is reacted with chlorine at 440 DEG C. and 30 lbs. pressure in a mol. ratio of 5.6 : 1 to produce vinyl chloride, hydrogen chloride and some ethylene dichloride, vinyl chloride is removed by passing the mixture through ethylene dichloride, obtained in the process, and the gaseous overhead is reacted at 190 DEG C. and 150 lbs. pressure in the presence of a supported copper chloride catalyst promoted with zinc chloride to produce ethyl chloride and some ethylene dichloride, ethyl chloride being separated by extraction with ethylene dichloride. It is stated that in a similar manner ethylene and bromine react to give ethylene and vinyl bromide, propylene and chlorine to give allyl and isopropyl chloride, propylene and bromine to give allyl and a propyl bromide, butene-1 and chlorine to give crotyl and butyl chlorides and butene-1 with bromine to give crotyl and butyl bromides. Specifications 468,016 and 502,611 are referred to.