Patent GB-624634-A (GB)
Title: Improvements in or relating to vinyl halides and process of preparing same
IPC: B01J31/22
Filed: 1946-10-10
Abstract: A catalyst for use in the production of vinyl halides by reacting acetylene with a hydrogen halide (see Group IV (b)), comprises a trivalent arsenic compound in which one or more valencies of the arsenic is satisfied by a beta-halovinyl group, any remaining valencies being satisfied by halogen.  Specified catalysts are beta-chlorovinyl dichloroarsine, bis - (beta - chlorovinyl) chloroarsine, tris-(beta-chlorovinyl) arsine and the analogous bromine and fluorine compounds, e.g. beta-bromovinyl dibromoarsine, bis-(beta-bromovinyl) bromoarsine, beta-fluorovinyl difluoroarsine and bis-(beta-fluorovinyl) fluoroarsine.  The catalysts may be used individually or mixed with each other or with other catalysts known to catalyse the reaction, e.g. mixtures of the arsenic compounds with the beta-halovinyl mercury compounds disclosed in Specification 617,335 may be used.  The catalyst may be supported on a surface-active carrier, e.g. activated charcoal, silica gel and diatomaceous earth, and this may be effected by dissolving it in a volatile solvent which is preferably the vinyl halide to be prepared, e.g. liquid vinyl chloride or vinyl bromide.  In examples: (1) a mixture of the beta-chlorovinyl arsines is prepared and a fraction boiling at 124-150 DEG  C. at 27 mm. is dissolved in liquid vinyl chloride and the solution poured on to activated charcoal, the vinyl chloride being then removed by evaporation and heating, the supported catalyst is then used to react a mixture of acetylene and hydrogen chloride in the vapour phase; (2) the catalyst is prepared by pouring a solution of mercuric chloride in methanol over activated charcoal, the methanol is removed and a solution of the mixed beta-chlorovinyl arsines prepared as in (1) in liquid vinyl chloride is poured over the catalyst carrier and the vinyl chloride removed by heating.ALSO:Vinyl halides are produced by reacting acetylene with a hydrogen halide in the presence of a catalyst comprising a trivalent arsenic compound in which one or more valences of the arsenic is satisfied by a beta-halovinyl group, any remaining valences being satisfied by halogen.  Specified catalysts are betachlorovinyl dichloroarsine, bis-(beta-chlorovinyl) chloroarsine, tris-(beta-chlorovinyl) arsine and the analogous bromine and fluorine compounds, e.g. beta-bromovinyl dibromoarsine, bis-(beta-bromovinyl) bromo-arsine beta-fluorovinyl difluoroarsine and bis-(beta-fluorovinyl) fluoroarsine.  The catalyst is preferably supported on a surface-active material, e.g. activated charcoal, silica gel and diatomaceous earth when the reaction is effected in the vapour phase, as is preferred. The catalyst may be deposited on the carrier by dissolving it in a volatile solvent which is preferably the vinyl halide to be prepared, e.g. liquid vinyl chloride or vinyl bromide.  The catalysts may be used individually or mixed with each other or with other catalysts known to catalyse the reaction, e.g. mixtures of the arsenic compounds with the beta-halovinyl mercury compounds disclosed in Specification 617,335 may be used.  If desired, the reaction may be carried out in solution, e.g. in an organic solvent.  In examples: (1) a mixture of the beta-chlorovinyl arsines is prepared and a fraction boiling at 124-150 DEG  C. at 27 mm. is dissolved in liquid vinyl chloride and the solution poured on to activated charcoal.  After removal of the vinyl chloride by evaporation and heating, a mixture of acetylene and hydrogen chloride is passed over the catalyst in a tube at about 200 DEG  C.; (2) a solution of mercuric chloride in methanol is poured over activated charcoal, the methanol removed and a solution of mixed beta-chlorovinyl arsines prepared as in (1) in liquid vinyl chloride is poured over the catalyst carrier.  The vinyl chloride is removed by heating and the catalyst used to react acetylene and hydrogen chloride at about 100 DEG  C.