Dehydrohalogenation of haloalkanes promoted by metal halides. Hydrogen halometalates formation and their use as hydrohalogenating agents

Article abstract of DOI:10.1016/S0040-4020(98)00404-9

In the dehydrohalogenation of 1,2-dihalo-1,1-diphenylethanes, 1, to 2- halo-1,1-diphenylethene, 2, either at 76°C or at 50°C, promoted by catalytic amount of the anhydrous bromides of Fe(III), Ru(III) and Al(III) and Fe(III) chloride the chemical transformation of the metal halides was observed. In reactions carried out in vacuum or under nitrogen atmosphere, the hydrogen halide eliminated from the organic substrate reacted with the metal halides rendering the unstable hydrogen perhalometalates H⁺(a)[MX(2+a)]^a-. We demonstrate that these compounds behave as hydrogen halide donors in hydrohalogenation of olefins at 4°C.