Why a cathodic activation by silver interface? Facile reductive homocoupling of 1-iodoalkanes

Smooth silver electrodes were used for the cathodic one-electron cleavage of primary alkyl iodides, RI. It has been shown that the catalytic process making possible the reduction of RI species is based on pre-reacting alkyl iodides with silver. It is then proposed that the transient species formed (via electron transfer?) at the silver interface could be written as R–Ag+, I−. Arguments to support this proposal are presented. Such chemically modified interfaces showed a specific electrochemical behaviour in propylene carbonate (PC) in the presence of tetraalkylammonium ammonium salts. Experimental conditions for yielding specifically a one-electron step for RI species are discussed and the resulting homocoupling is evidenced.