GB617335A - Improvements in or relating to vinyl chloride and process of preparing the same - Google Patents

Abstract

In the production of vinyl chloride by reacting acetylene with hydrogen chloride (see Group IV (b)), the catalyst comprises as an essential component a bivalent mercury compound in which one of the valences of the mercury is satisfied by a beta-halovinyl group and the remaining valence is satisfied by halogen or another beta-halovinyl group. In examples, the catalyst is prepared by (1) pouring a solution of beta-chlorovinyl mercuric chloride (purified by recrystallization from benzene) in acetone on to silica gel and then removing the acetone; (2) pouring a solution of beta-chlorovinyl mercuric chloride and mercuric chloride in acetone on to silica gel and removing the acetone, and (3) by pouring a solution of bis-(beta-chlorovinyl) mercury in liquid vinyl chloride over activated charcoal and removing most of the vinyl chloride. Diatomaceous earth is also specified as a surface active carrier and the catalysts may be mixed with each other or with known catalysts for the reaction, e.g. mercuric chloride, bismuth trichloride and metallic mercury.ALSO:Vinyl chloride is produced by reacting acetylene with hydrogen chloride in the presence of a previously prepared catalyst comprising as an essential component a bivalent mercury compound in which one of the valences of the mercury is satisfied by a beta-halo-vinyl group, and the remaining valence is satisfied by halogen or another beta-halo-vinyl group. Specified catalysts are beta-chlorovinyl mercuric chloride and bis-(beta-chlorovinyl) mercury and the corresponding bromovinyl and fluorovinyl compounds. The catalyst is preferably supported on a surface-active carrier for use in a vapour phase reaction, e.g. on activated charcoal, silica gel or diatomaceous earth. The catalysts may be used individually or mixed with each other or with known catalysts for the reaction, such as mercuric chloride, bismuth trichloride and metallic mercury. In depositing the catalyst on the carrier, a catalyst solution in a solvent, e.g. acetone, or preferably in liquid vinyl chloride is poured on the carrier and the solvent evaporated. The reaction may be effected in solution, e.g. in water or an organic solvent. In examples, acetylene and hydrogen chloride are reacted in the vapour phase over a catalyst comprising (1) beta-chlorovinyl mercuric chloride (purified by re-crystallization from benzene) on silica gel, prepared by pouring an acetone solution of the catalyst on to the silica gel and then removing the acetone; (2) a catalyst prepared by pouring a solution of beta-chlorovinyl mercuric chloride and mercuric chloride in acetone on to silica gel and then removing the acetone; (3) a catalyst prepared by pouring a solution of bis-(beta-chlorovinyl) mercury in liquid vinyl chloride on activated charcoal and removing most of the vinyl chloride. The Specification as open to inspection under Sect. 91 is not restricted to the production of vinyl chloride and states that vinyl bromide or other vinyl halide may be produced from acetylene and the appropriate hydrogen halide in the presence of catalysts such as betabromovinyl mercuric bromide and beta-fluorovinyl mercuric fluoride. This subject-matter does not appear in the Specification as accepted.