GB819420A - Improvements in the production of saturated chloro-hydrocarbons - Google Patents

Abstract

Saturated chlorinated hydrocarbons are prepared by the addition of chlorine to olefinic, cyclo-olefinic or alkenyl-aromatic hydrocarbons or their halogen-substituted derivatives in the presence of a catalyst which contains a platinum metal or a compound of one of the platinum metals at temperatures of up to 300 DEG C. The reaction may be effected in the liquid phase, e.g. in a melt or in solution or in an emulsion, or in the gas phase. Temperatures as low as - 25 DEG C. are mentioned for solution or emulsion working. Catalyst metal compounds specified are the chlorides and oxides. They may be used in conjunction with carriers such as aluminium oxide, silica gel, pumice, fuller's earth or active carbon. Specified compositions are palladium, iridium or rhodium chloride on aluminium oxide. Generally 0.5 to 15 per cent by weight of catalytic substance is used referred to the total weight of the catalyst. Catalysts for liquid phase operation are preferably pre-treated with halogen or hydrogen halide, if desired at elevated temperature. For gas phase operation the catalyst may be rigidly arranged or may move in the reaction vessel, e.g. in the fluidized state. The catalyst is preferably kept in motion in liquid phase operation. The process may be applied to mixtures of olefines as are present in cracking gases or in petroleum fractions. Saturated hydrocarbons may be present as inert diluent or solvent. It may be desirable to lead an inert organic solvent, such as a chlorinated hydrocarbon which cannot be further chlorinated under the reaction conditions, into the reaction chamber with the reactants to prevent crystallization of high melting product. The chlorine may be mixed with nitrogen or other inert gas and is preferably caused to circulate in the reaction vessel. In general the chlorine is used in the ratio of 1 to 5 parts by weight per part of initial material. The process may be carried out under reduced, normal or increased pressure. In examples: (1) 1,2-dichlorpropane with some 1,2,3-trichlorpropane is prepared by the gas phase chlorination of propene using palladium chloride/alumina catalyst; (2) a mixture of cyclo-octene with cyclo-octane is chlorinated in the gas phase to 1,2-dichlorocyclo-octane using PdCl2/Al2O3, PdCl2/SiO2, IrCl3/Al2O3, RhCl3/Al2O3 and NaPtCl6/SiO2 catalysts; (3) a ,b -dichloroethylbenzene is prepared by chlorinating styrene in refluxing CCl4 solution using PdCl2/Al2O3 catalyst and passing in gaseous chlorine; (4) cyclo-octyl dichloride from cyclo-octene; and (5) 1,2,3-trichlorpropane from allyl chloride are prepared using cold CCl4 solution and adding the chlorine in solution in CCl4.