Electrochemical induction

Rossi, 1983), light-induced and solvated-electron-induced reactions (Bun-nett, 1978), electrochemical induction (Saveant, 1980a), synthetic aspects (Beugelmans, 1984 Norris, 1990 Wolfe and Carver, 1978), photochemical induction of the reaction at heteroaromatic carbon centres (Lablache-Combier, 1988). There is no point in repeating here the extensive lists of reactions contained in these review articles. We shall just underline a few points and report recently available findings. 

Alkoxide or aryloxide anions are also reputed to be inactive in Sr I reactions. There is, however, one example of such a reaction at an sp carbon the nitro-derivative of 4-nitrocumyl reacts with phenoxide and 1-methyl-2-naphthoxide ions yielding the corresponding ethers (Kornblum et al., 1967). A similar reaction has been reported for halobenzenes in t-butyl alcohol upon stimulation by sodium amalgam (Rajan and Sridaran, 1977). This reaction could not, however, be reproduced (Rossi and Pierini, 1980) and other attempts to make phenoxide ions react at sp carbons have been equally unsuccessful (Ciminale et al, 1978 Rossi and Bunnett, 1973 Semmelhack and Bargar, 1980). It has been found, more recently, that phenoxide ions react with a series of aryl halides under electrochemical induction, but that the coupling occurs at the p- or o-phenolic carbon rather than at the phenolic oxygen (Alam et al, 1988 Amatore et al, 1988). This is... 

Electrochemical induction of the reaction (Pinson and Saveant, 1974), as shown to occur in a number of cases with aromatic and heteroaromatic substrates (Saveant, 1980a, 1986, 1988), also provides evidence for the Sr I mechanism. The electrochemical approach allows, in addition, a quantitative analysis of the mechanism and reactivity problems and will be described in this connection in the next subsection. 

Fig. 17 Indirect electrochemical induction of Sr I reactions. Cyclic voltammetry of (a) 4-cyanopyridine (2.2 mM) in the absence (—) and presence (—) of 8.9 mM 2-chlorobenzonitrile (b) 4-cyanopyridine (6.6 mM) in the presence of 8.9 mM 2-chloro-benzonitrile and 35 mM PhS -. (Adapted from Amatore el al., 1984b.)...

On the other hand, analysis of the cyclic voltammetric data pertaining to the direct and indirect electrochemical induction of Sr I reactions by means... 

Initiation by electrochemical induction may have the disadvantage of low yields of substitution due to the reduction of the radicals formed near the electrode, mainly in those cases in which the radical anion of the halide compound fragments at a considerably high rate. Redox catalysis, that is activation involving a suitable ET mediator, is an important means to avoid termination steps in electrochemically induced reactions. This approach has been extensively studied by the Saveant group15. A general equation has been proposed in order to predict the yield of ET-initiated S l chain reactions and related mechanisms under preparative electrochemical conditions in the presence of a redox mediator35. 

Additionally, the mediated electrochemical induction has also been used successfully with high yield in the synthesis of phneylselenobenzonitriles and phneyltellurobenzoni-triles [186]. 

Other examples have been provided by the anodically initiated isomerization of several decarbene metal carbonyl couples [197]. Electrochemical induction of chemical reactions can also be successfully used for conversion of alcoolates into ketones with simultaneous reduction of aromatic halides [198], the tetramerization of aziridines [199], or ligand substitution [200] in organometallic compounds. A useful review on this subject was published [201]. 

D. M. Thompson, Electrochemical induction of alkali-silica reaction in concrete . Materials and Structures, 1991, 24, 359-361. 

Adenier, A., E. Cabet-Deliry, A. Chaussd, S. Griveau, F. Mercier, J. Pinson, and C. Vautrin-Ul. Grafting of nitrophenyl groups on carbon and metallic surfaces without electrochemical induction. Chem. Mater. 17, 2005 491-501. 

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