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

摘要

In the dehydrohalogenation of 1,2-dihalo-1,1-diphenylethanes, 1, to 2-halo-1,1-diphenylethene, 2, either at 76 degrees C or at 50 degrees C, promoted by catalytic amount of the anhydrous bromides of Fe(III), Ru(III) and AI(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-n(+)[MX3+n](n-). We demonstrate that these compounds behave as hydrogen halide donors in the hydrohalogenation of olefins at 4 degrees C. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 28]