Electrochemical reduction of 2-chloro-2-cyclohexenones

The electrochemical reduction of the 2-chloro-2-cyclohexenones 2a–2c (mercury cathode, CH₃CN,Bu₄NBF₄) was studied by means of cyclic voltammetry, dc polarography, coulometry and chemical product analysis. The results were compared to those obtained with the analogous 2-cyclohexenones 1a–1c. Due to the chloro-substituent on C—2 the half wave potentials E_1/2 for the first electron transfer step become less cathodic and the overall mechanism of reduction of a chloro-substituent on C—6 is modified. In addition, strong inhibition effects were observed in the cyclic voltammograms of compound 2 and it was found that other 2-halogeno-2-cycloalkenones exhibit a similar behaviour.