Electrolytic Hydrogenation of Organic Substances

Electrolytic hydrogenation of unsaturated compounds might have advantages over the ordinary gas phase catalytic processes as the reaction rate, and possibly the selectivity, could be controlled through the potential of the electrode. Also, the electrochemical system may provide a much stronger reducing condition than with the gas phase reactions. 

Survey of the vast field of chemistry of electroreduction of various substances is beyond the scope of this short chapter. Therefore, only 

It might appear likely that electroreduction processes take place directly by electronst on metals which have high hydrogen overpotential and by H(a) on low overpotential metals. Indeed, e.g., electroreduction of acrylonitrile to adiponitrile on Pb or Hg takes place by electronation, followed by proton addition and dimerization, while electrolytic olefin hydrogenation on Pt takes place by transfer of H(a) to the organics. Nevertheless, such 

The first step of electroreduction of maleic acid (M) on Hg was reported to be electron transfer forming an ion radical, followed by addition of H  

However, on Pt and other electrocatalytically active metals, the C=C double bond of maleic acid (or ethylene and its derivatives ) is considered to be reduced by H(a), 

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Why is there such a deep interest in this field We may point out some of the probable reasons, such as (a) a hope to elucidate the HER mechanism as a prototype for heterogeneous reaction kinetics, (b) to obtain a systematic view on the catalytic properties of various metals, (c) the existence of many related important fields such as corrosion of metals, electrolytic hydrogenation of organic substances, etc., and (d) some more up-to-date reasons, such as efficient hydrogen production or use of hydrogen in fuel cells, and seeking a prospect toward the so-called hydrogen economy. 

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