Reduction of alcohols and organic halides by metal salts

Abstract

Abstract It has been demonstrated that halide ions are not essential for the reduction of triphenylcarbinol and diphenylcarbinol to hexaphenylethane and sym -tetraphenylethane, respectively, by vanadous and chromous salts. Benzyl and allyl halides are reduced by chromous salts to either the coupled products, bibenzyl and biallyl, or to toluene and propylene, respectively. Anhydrous solvents and the slow addition of the chromous salt to the organic halide solution favor the formation of coupled products relative to the monomeric products of further reduction. The ratio of bibenzyl to toluene is much larger from benzyl iodide and benzyl bromide than from benzyl chloride. The intermediate benzylchromium complex, probably C 6 H 5 CH 2 Cr(H 2 O) 5 2+ , reacts with allyl bromide to form 4-phenyl-1-butene. Saturated aliphatic halides, such as isopropyl iodide, are reduced only to monomeric hydrocarbons by chromous salts. A mechanism is proposed is proposed for these reactions.