Divided cells electrosynthesis

The addition of carbanions, generated electrochemically by reduction of the carbon-halogen bond, to carbon dioxide has been examined under a variety of experimental conditions. Direct electrosynthesis of carboxylic acids in a divided cell using an aprotic solvent and a tetraalkylammonium salt as electrolyte is most sue-... 

The electrosynthesis of propylene oxide (PO) has already been studied intensively by Bayer 49) in the sixties, and has been scaled up to the pilot scale. The synthesis was carried out in a divided cell at Ti/RuOz anodes and steel cathodes. 

Electrosynthesis — Synthesis performed with the help of -> electrolysis. Electrosynthesis is performed both on laboratory as well as on an industrial scale, and both organic and inorganic compounds are synthesized. In most cases, electrosynthesis affords divided cells, i.e., separation of the -> anolyte and -> catholyte by a -> diaphragm to prevent reactions between the products of the reaction proceeding at the -> anode with those formed at the -> cathode. 

The examples illustrate the diversity as well as the common features of a paired electrosynthesis. One can start with one or two substrates to generate one or two products. Electrode processes can be mediated or direct. Undivided and divided cells are employed in paired electrosyntheses. But as in the BASF phthahde example, it is crucial for the synthesis of glyoxylic acid, sorbitol, and methyl ethyl ketone that the cathodic process is the reduction of the substrate and not the reduction of protons because in these cases protons are generated at the anode and the electrolysis takes place in aprotic solvent. Therefore effects that minimize the overpotential of hydrogen have to be omitted. Reaction control is important in all described examples, and consequently the cell and the setup have to fit for each case. Work-up and product isolation are significant for a successful synthesis and can be even more challenging in a paired synthesis. 

Figure 3.2 The divided electrochemical cell for electrosynthesis. (From Bioanalytical Systems, A Handbook of Electroanalytical Products, Bioanalytical Systems, Inc., reproduced with permission.)...

Fig. 2.39 Typical laboratory pilot-scale facilities using divided, parallel-plate cells, (a) The major components of a flow system for anodic electrosynthesis. After Reilly Tar and Chemical Corp.) (see also Fig. 6.7) (b) A small laboratory pilot facility based on the MP ElectroCell. Here, an electrodialysis process is being performed. The facility is also used for electrosynthesis by means of simple modification of the cell components and process streams. (Courtesy Electrosynthesis Co., Inc.), (c) A DEM cell for synthesis. (Courtesy Electricity Council Research Centre and University of Strathclyde.)...

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