Advances in Electrochemical Hydrogenation Since 2010

Abstract

A commitment to developing a convenient, efficient, and safe hydrogenation strategy is one of the main focuses of industry and academia. Electrochemical hydrogenation brings greener and gentler opportunities for the selective hydrogenation of unsaturated compounds and the incorporation of deuterium atoms to desired products with traceless electrons as redox reagents in the absence of highpressure hydrogen. In this account, recent advances in electrochemical hydrogenation or transfer hydrogenation of unsaturated compounds since 2010 are summarized. The reaction features, limitations, substrates scopes, mechanism of these hydrogenation reactions are discussed in this review. We hope this account will contribute to future developments to broaden the scope of electrochemical hydrogenation or transfer hydrogenation. Alkenes and Alkynes 2.3. Electrochemical Hydrogenation of Unactivated Alkenes and Alkynes 2.4. Electrochemical Hydrogenation of N-Heteroaromatics 2.5. Electrochemical Birch Reduction 3. Conclusion

Opening the pathway towards a scalable electrochemical semi-hydrogenation of alkynolsviaearth-abundant metal chalcogenides

“…5 Regarding hydrogenation reactions in particular, electrochemistry can effectively mitigate safety hazards, transport and storage costs as well as carbon dioxide emissions associated with the supply of highly pressurized dihydrogen. 6,7 In the case of electrosynthesis instead of gaseous H 2 , the solvent, ideally water, acts as the proton source, while the possibility to directly use electrons from renewables enables a sustainable implementation. 8 By carefully tuning the applied potential, temperature and electrolyte, a variety of functional groups such as ketones, 9 aldehydes, esters, 10 olefins, 7 alkynes, 11 nitriles 12 and oximes 13 have been electrochemically hydrogenated in recent years.…”

“…6,7 In the case of electrosynthesis instead of gaseous H 2 , the solvent, ideally water, acts as the proton source, while the possibility to directly use electrons from renewables enables a sustainable implementation. 8 By carefully tuning the applied potential, temperature and electrolyte, a variety of functional groups such as ketones, 9 aldehydes, esters, 10 olefins, 7 alkynes, 11 nitriles 12 and oximes 13 have been electrochemically hydrogenated in recent years.…”

Electroreduction of Carbonyl Compounds Catalyzed by a Manganese Complex

“…Furthermore, electrochemistry offers the advantage to simultaneously analyze the coupled electrochemical and chemical processes, thus providing a deeper insight into the mechanism of the reaction. Electrochemical reductions of π-systems that include the transfer of only electrons and protons are very useful alternatives to chemical reductants such as in the Birch or Clemmensen reduction, though they usually suffer from rather large overpotentials, leading to undesired side reactions such as hydrogen evolution reaction. , Merging organometallic catalysis and electrochemistry is a promising strategy to reduce the overpotential and direct the selectivity toward the specific target . It combines the advantage of highly tailored catalysts and energy-efficient synthesis.…”

Proton Independent Electrocatalytic Transfer Hydrogenation of Styrene with [(tBuPCP)Ir(H)(Cl)] and Water

“…29 Both, noble metal electrodes and molecular catalysts are employed for these conversions. 30 The dominant common aspect of all these examples is that they rely on H + reduction, often in highly acidic electrolyte. The working principle is to either generate H 2 or surface hydrides in situ at the electrode for immediate consumption by a coupled hydrogenation reaction.…”