Electrosyntheses from aromatic aldehydes in a flow cell. Part I. The reduction of benzaldehyde.

The reduction of benzaldehyde in acidic water-methanol mixtures has been re-investigated in a membrane flow cell with a lead cathode with the objective of defining conditions where le- reduction occurs and the C6H5CH.OH radical intermediate is formed in high selectivity. It is shown that it is the cathode potential which controls the ratio of le-/2e- product (i.e. hydrobenzoin to benzyl alcohol) and a high rate generation of the radicals is also favoured by an efficient mass transport regime.