J. Phys. IV France 04 (1994) C1-175-C1-184
Electrosynthèse organique en continu. Méthodes directes et indirectesC. MOINET
Laboratoire d'Electrochimie, URA 439 du CNRS, Université de Rennes I, Campus de Beaulieu, 35042 Rennes cedex, France
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.
© EDP Sciences 1994