The Reductive Coupling Reactions of Some Chloromethylbenzene Derivatives with Iron(II) and Copper(I) Complexes

Abstract
The reductive coupling reactions of some chloromethylbenzene derivatives with ferrous and cuprous chloride in ethanol or in acetonitrile and the effect of some additives on this reaction have been investigated. Benzotrichloride has been reduced selectively to tolan tetrachloride with ferrous chloride, while with cuprous chloride-ethylenediamine (a stronger reductant than ferrous chloride) mixtures of tolan and tolan dichloride or tolan tetrachloride are obtained depending on the condition. Similarly benzal chloride, diphenylmethyl chloride and diphenyldichloromethane are also reduced to give coupling products. In case of ferrous chloride the addition of ethylenediamine or pyrophosphoric acid raises the yield considerably and in case of cuprous chloride selection of the ratio, organic halide: copper (I): ethylenediamine, makes it possible to control the product distribution. The reaction mechanism and the effect of the additives are discussed.

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