Reduction of Trichloromethyl Compounds by Hydrogen Donors Induced by Transition Metal Carbonyls, their Complexes, or their Salts

Abstract

A new method of selective reduction of various trichloromethyl derivatives is described. The method may be applied to reduce α,α, α-trichloro-, α,α,α,β,β-pentachloro-, α,α,α,ω-tetrachloro-, and α,α,α,γ-tetrachloroalkanes as well as for gem-trichloroalkanes containing aromatic or functional groups in side chains, to the corresponding α,α-dichloromethyl compounds. Secondary alcohols, mercaptans, silicon hydrides, amines, and amides are employed as reducing agents. The reaction is initiated by transition metal carbonyls, their complexes, or their salts. 1. Introduction 2. Structural Effects of the Substrate 2.1. Tetrachloromethane and Trichloromethane 2.2. α,α,α-Tri- , α,α,α,ω-Tetra-, and α,α,α,γ- Tetrachloroalkanes 2.3. α,α,α,β-Tetrachloro- and α,α,α, β,β-Pentachloroalkanes 2.4. 2,2-Bis[4-chlorophenyl]-1,1,1-trichloroethane (DDT), its Analogues, and Related Compounds 2.5. Trichloromethyl Compounds Containing Functional Groups as Substituents 3. Conclusions