Electrosynthèse organique en continu. Méthodes directes et indirectes

Abstract
Time scale is an important parameter in organic electrosynthesis, particularly when chemical reactions occur during electrochemical processes. Because a long time is necessary to reach good yields with cells using planar electrodes, we studied electrolysis cells with porous electrodes of high specific area (graphite felt). A disposition with two or three electrical circuits provides a good distribution of working potential and, consequently, a good selectivity of electrochemical processes. Cells can be adapted with only one porous electrode to realize an oxidation or a reduction or, with two closely consecutive porous electrodes of opposite polarities ("redox" flow cell) to do a reduction then an oxidation or vice versa. Direct large-scale preparations at one or two porous electrodes of various organic compounds are achieved with good yields (> 90-95%). Particularly unstables species can be obtained. Another application of the cell with one porous electrode concerns indirect electrolysis. The indirect electrolytic process emploies a water soluble redox reagent which is continuously recycled and the chemical reaction which occurs out of the cell, is a two-phase process.