GB807501A - An improved method of producing olefinic compounds - Google Patents

Abstract

Olefines are prepared by the dehydro-chlorination of the corresponding chloro-compound by heating with a metal salt dehydrochlorination catalyst in the presence of a polar organic solvent or organic solvent boiling above 140 DEG C., the reaction mixture forming a homogeneous liquid phase, and removing the hydrogen chloride and olefine as they are formed. Olefines, cycloalkenes and aromatic compounds containing an olefinic double bond in a side-chain, e.g. styrene, may be thus prepared. In examples, the dehydrochlorination of monochlorocyclohexane to cyclohexene is described. Solvents referred to are organic acids such as acetic, propionic, butyric and benzoic acids; aromatic nitroderivatives such as nitrobenzene; alkyl-phenols, decahydronaphthalene, aromatic chlorinated compounds such as ortho-dichlorobenzene and chloronitrobenzene, and high-boiling polar compounds such as dichloracetic acid and trichloracetic acid. Catalysts referred to are metallic halides, e.g. ferric, aluminium, antimony, manganese, zinc and stannic chlorides. The process can be carried out continuously by introducing the chloro-compound into the heated mixture of solvent and catalyst at a rate to maintain the reaction volume constant and continuously removing by distillation the olefine and hydrogen chloride. Batch operation may also be used.