Adiponitrile, electrochemical synthesis

Electrochemical processes are often touted as being green chemistry because electricity is considered inexpensive, and toxic metal reagents are usually avoided. Electrochemical processes have produced tons of bulk chemicals [37], the best-known of which may be adiponitrile from reductive dimerization of acrylonitrile (Figure 13.17) [38]. An electrochemical synthesis to manufacture fenoprofen is shown in Figure 13.18, with the magnesium provided as a sacrificial electrode [39], Flow cell technology has been used for these operations on a commercial basis. 

Raney-Ni powder as cathode material was used by Chiba and coworkers to electrohydrogenate pentanenitrile, heptanenitrile, adiponitrile, benzonitrile and phenylacetonitrile in alkaline methanol to the corresponding amines in ca 70% yield. The same electrode was used for the electrochemical synthesis of aminonitriles starting with adiponitrile and azelanitrile. In the case of adiponitrile a through study of experimental conditions revealed that significantly lower current densities than those used previously... 

Dai JJ, Hnang YB, Eang C, Guo QX, Eu Y. (2012). Electrochemical synthesis of adiponitrile from the renewable raw material glutamic acid. ChemSusChem, 5, 617-620. 

A special feature of the electrochemical synthesis of adiponitrile and other dinitrides is their behavior in aqueous solutions of the hydrotropic salts which serve as electrolytes. 

Reactions of this type are called electrochemical hydrodimerization. They are of great value for the synthesis of various bifunctional compounds. A reaction that has found wide commercial nse is the hydrodimerization of acrylonitrile to adiponitrile (the dinitrile of adipic acid) ... 

A synthesis of great industrial interest is the electrochemical anodic reductive dimerisation of two molecules of acrylonitrile to give adiponitrile, from which adipic acid and 1,6-hexanediamine are prepared by hydrolysis and reduction, respectively, of the two nitrile groups. Polycondensation of the resulting products leads to Nylon 66 (Scheme 5.27). 

Another area of great potential involves the production of high-value-added organic chemicals by electrochemical methods of synthesis. The high yield of these routes is particularly attractive for specialty chemical markets. Larger scale processes that have been commercialized include tetraalkyllead (5) and adiponitrile. 

Thus, the electrochemical route for synthesis of adiponitrile effectively halved the demand for adipic acid. 

Very many types of organic synthesis can now be carried out electrochemically, often more advantageously than by other means. Organic electrosynthesis, always multi-disciplinary, now includes photoelectrochemistry, electro-catalysis, bioelectrochemistry and others. Some of the scientific and technological developments which led to the present status of the field will be cited the use of potential control, the invention of the potentiostat, the combination of electrochemistry with spectroscopy, the use of ion-selective membranes the large-scale production of sorbitol, adiponitrile, and dimethyl sebacate. 

In recent years electro-organic synthesis has been gaining in importance[9]. The first to be carried out on an industrial scale was that of adiponitrile, the raw material for large scale production of nylon. However, the production of many more substances, in particular those of pharmaceutical interest, has been set up at many points around the world in limited volumes achievable with small-scale electrochemical reactors. A review of these products is given in Table 1. 

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