This investigation applied the techniques of polarography and controlled potential electrolytic reduction to the study of a series of unsymmetrical benzils. Eleven unsymmetrical benzils were synthesized and studied in 50% ethanol-water (by volume) solvent systems buffered at pH 1, 5, and 13. The results showed that, with unsymmetrical benzils substituted with electron-withdrawing or electrondonating groups, the carbonyl closest to the ring with the least electron-donating power was the preferred reaction site. However, the dicarbonyl system was nevertheless reduced as a unit, and Hammett sigma values of disubstituted symmetrical benzils were approximately additive. This was ascertained by comparing the ease of reduction of eight unsymmetrical benzils to the ease of reduction of the corresponding disubstituted symmetrical benzils. It was proposed that the electrons were added to the oxygen of one carbonyl, and that the second carbonyl was involved in the reduction chiefly through complete polarization of the dicarbonyl system at the electrode. In general, the reduction of unsymmetrical benzils appeared to follow the same path previously reported for symmetrical benzils.

Dans ce travail de thèse il a été rapporté que, pour la premiere fois, l'utilisation de TMSCl associée au NaI permet de réduire régiosélectivement divers composés de type benzile dans le chlorure de méthylene. Par ailleurs, nous avons montré que ce couple de réactifs est aussi capable de réduire diverses arylalkylcétones aussi bien que des alpha-cétoesters -cétoacides et hydrazinoesters avec des sélectivités totales. Le mécanisme original de type radicalaire a été étudié au travers de nombreuses expériences. / In this work, we have described that, for the first time the TMSCl - NaI association was used to regioselectively reduce a variety of alpha diketones as benzils in methylene chloride. Moreover, we showed that this association was able to reduce various arylalkylketones as well as alpha ketoesters, ketoacids and hydrazinoesters with total selectivity. The mechanism of action is probably due to radicals was fully studied with many experiments.