Electrochemistry of acyl halides

Cyclic voltammograms for reduction of heptanoyl chloride at carbon and mercury electrodes in acetonitrile containing tetraalkylammonium perchlorates exhibit two waves; the first wave is attributed to cleavage of the carbon-chlorine bond, whereas the second wave arises from reduction of electrolytically generated heptaldehyde and hydrolytically formed heptanoic anhydride. Electrochemical reduction of cyclohexanecarbonyl chloride at a potential slightly negative of its first cathodic wave generates cyclohexanecarbox-aldehyde in 45% yield. Deuterium-labeling studies employing deuterium oxide and acetonitrile-;Electrochemical reduction of phenylacetyl chloride generates phenylacetaldehyde in 3% yield, whereas electrolysis of hydrocinnamoyl chloride leads to hydrocinnamaldehyde in 40% yield. Investigations conducted with acetonitrile-;An investigation of the electrochemistry of 2-furoyl chloride indicates that a tetrameric species, (1,2-bis(2-furyl)-1,2-ethenediyl) -bis(2-furoate), is the only product generated electrochemically in the absence of proton donors. As with 2-furoyl chloride, only one electrogenerated product is obtained from the reduction of trimethylacetyl chloride; trimethylacetaldehyde forms in 45% yield, whereas hydrolytically formed trimethylacetic anhydride accounts for 55% of the starting material.;At carbon and mercury cathodes in acetonitrile containing tetraethylammonium perchlorate, cyclic voltammograms for the reduction of phthaloyl dichloride exhibit six reduction waves; the first wave is due to electrolytic cleavage of one carbon-chlorine bond, whereas the remaining waves arise from electrochemically and hydrolytically generated products. A second diacyl halide, glutaryl dichloride, also produces cyclic products, 5-chlorovalerolactone and valerolactone, upon reduction as well as glutaric anhydride and an unidentified polymeric species.