GB744076A - Improvements in or relating to the production of ethylene chlorohydrin and acetylene - Google Patents

Abstract

A saturated hydrocarbon is pyrolysed to produce a mixture containing substantial proportions of acetylene and ethylene, an acetylene-ethylene mixture is separated and reacted with chlorine in aqueous phase under chlor-hydrination conditions, ethylene chlorhydrin is recovered from the product, and a residual gas enriched in acetylene separated. This may be reacted in a second stage with a reagent selectively reacting with acetylene. Normally gaseous or liquid saturated hydrocarbons such as natural gas or gasolines or higher boiling fractions, but preferably ethane, may be cracked at 1100-1600 DEG C., if desired in presence of steam or other inert gas, to give acetylene and ethylene, preferably in equimolar proportions. The product is separated, as by adsorption and desorption, into a saturated fraction, an acetylene-ethylene fraction, and a higher boiling fraction. The chlorhydrination is effected at about 10-80 DEG C. in one or more stages. In place of chlorine per se, sodium or calcium hypochlorite may be used. Suitably, the hydrocarbons and chlorine are charged to the bottom of a water-flooded tower, water being introduced at the base and overflowing at the top with a content of up to 5 per cent hydrogen chloride and 10 per cent chlorhydrin. Exit gases may be recycled until the ethylene is substantially removed. The residual acetylene is then reacted, suitably to an extent such that a tail gas suitable for recycle to the first stage with fresh feed, as in Specification 744,079, is obtained. The acetylene may be converted with hydrogen chloride to vinyl chloride as described in the above Specification; to vinyl acetate as in Specification 744,077; to dichlorethylene with hydrogen and air as in Specification 744,081; to acrylonitrile as in Specification 744,079; to acetylene alcohols by absorption in a suspension of potassium hydroxide as in Specification 744,082 and treatment with aldehydes or ketones as in Specification 744,079; to butynediol-1,4 with formaldehyde, to vinyl ethers with alcohols or to styrene with benzene, as described in the same Specification. Examples illustrate the chlorhydrination with water and chlorine, and conversion of the acetylene-enriched residual gas to vinyl chloride, dichlorethylene, vinyl acetate and butynediol-1,4, also its absorption in a suspension of potassium hydroxide in xylene followed by heating to give substantially pure acetylene.