CONTINUOUS ORGANIC ELECTROSYNTHESIS - DIR ECT AND INDIRECT METHODS

Time scale is an important parameter in organic electrosynthesis, part icularly when chemical reactions occur during electrochemical processe s. Because a long time is necessary to reach good yields with cells us ing planar electrodes, we studied electrolysis cells with porous elect rodes of high specific ama (graphite felt). A disposition with two or three electrical circuits provides a good distribution of working pote ntial and, consequently, a good selectivity of electrochemical process es. Cells can be adapted with only one porous electrode to realize an oxidation or a reduction or, with two closely consecutive porous elect rodes of opposite polarities (''redox'' flow cell) to do a reduction t hen an oxidation or vice versa. Direct large-scale preparations at one or two porous electrodes of various organic compounds are achieved wi th good yields (> 90-95%). Particularly unstables species can be obtai ned. Another application of the cell with one porous electrode concern s indirect electrolysis. The indirect electrolytic process emploies a water soluble redox reagent which is continuously recycled and the che mical reaction which occurs out of the cell, is a two-phase process.