REACTIVITY OF ALPHA,ALPHA'-DICHLOROKETONES TOWARDS ANIONS ELECTROGENERATED AT CARBONIUM AND OXYGEN-ATOMS - ELECTROCHEMICALLY-INDUCED FAVORSKII REARRANGEMENT .2.

Electrolyses of solutions containing alpha,alpha'-dichloroketones 1a o r 2a were carried out, on mercury pool or glassy carbon cathode, at a potential sufficiently negative to allow two-electron cleavage of the C-Cl bond. The effects of the presence of carboxylic acids 3a,b, pheno ls 4a-f, or carbon acid 5 in the solutions were evaluated. Depending o n the type of acidic substrate, it was possible to isolate from the ca thodic solutions the Favorskii-rearrangement products 9m, 10m, 11 and 12, as well as dechlorinated ketones 1b and 2b and the addition produc ts 7m and 8m. The conditions under which it was possible, by electroch emical means, to induce the Favorskii rearrangement between dichloroke tones 1a and 2a and the acidic substrates are discussed. Evidence was gained by voltammetric analysis that the rates of formation of the Fav orskii adducts 9a-f depend on the structures of the corresponding phen ols 4a-f. By employing electrogenerated bases, it was possible to obta in alpha,beta-unsaturated ketones at potentials less negative than req uired for the direct reduction of 1a and 2a.