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Journal of the Electrochemical Society, Vol.152, No.7, E222-E229, 2005
Catalytic reduction of 1,6-dihalohexanes by nickel(I) salen electrogenerated at glassy carbon cathodes in dimethylformamide
Reaction between stoichiometric amounts of 1,6-dihalohexanes and electrogenerated nickel(I) salen in dimethylformamide containing 0.10 M tetramethylammonium tetrafluoroborate affords cyclohexane in up to 78% yield. Arising via a radical pathway, an omega-haloalkylnickel(II) species is a proposed intermediate for these reductions in which alkanes, 1-alkenes, and aldehydes are also produced. In cyclic voltammetric studies at scan rates of 5-25 mV s(-1), formation of a passivating film on the surface of the carbon cathode has a dramatic effect on the catalytic reduction of 1,6-dihalohexanes, but this electrode fouling can be overcome by addition of acetic acid to the medium. For controlled-potential electrolyses involving the reduction of a 1,6-dihalohexane with catalytic amounts of electrogenerated nickel(I) salen in the presence of excess acetic acid, most of the substrate is converted into three different esters (hexyl acetate, 1,6-diacetoxyhexane, and dodecyl acetate) which arise via nucleophilic (S(N)2) attack of acetate ion on the dihaloalkane. (c) 2005 The Electrochemical Society. All rights reserved.