A Review on the Critical Role of H₂ Donor in the Selective Hydrogenation of 5‐Hydroxymethylfurfural

Abstract

The selective hydrogenation of 5-hydroxymethylfurfural (HMF) has been of great interest to many scientists and researchers. However, conventional hydrogenation inevitably requires the use of gaseous hydrogen as a reducing agent, which is detrimental to its storage and transport. In this regard, other economical and environmentally friendly strategies, such as catalytic transfer hydrogenation/hydrogenolysis without exter-nal molecular H 2 , become more and more attractive. This Review provides the status and insight into the current research of hydrogenating HMF to high-value chemicals, using formic acid, alcohols, polymethylhydrosiloxane, water, and sodium borohydride as hydrogen donors and explains the hydrogenation mechanisms and the related hydrogenation characteristics of different hydrogen donors in the catalytic systems.

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

“…In contrast, the integration of Ni-foam as the cathode material demonstrates a decreased activity for the ECH with a total FE-ECH value of just 15%. 8…”

“…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.…”

Insights into the molecular mechanism of a new efficient whole-cell biocatalystEnterobacter ludwigiiYYP3 in 5-hydroxymethylfurfural reduction

“…Collectively, the chemical processes have good catalytic effects, but most of them are under severe conditions, especially high temperatures (>100 °C) and pressures (>10 bar). 60 Moreover, the use of H 2 as a hydrogen donor is high-cost and has storage risks, transportation constraints, and safety concerns. 61 The biocatalytic process mediated by E. ludwigii YYP3 in this study has emerged as a promising alternative to chemical approaches for green and clean value-added conversion of HMF, since the reaction can be conducted under mild conditions with excellent selectivity and a high space time yield.…”

Mechanistic Insight into Favorable Aldehyde Hydrogenation over Hydroxymethyl Hydrogenolysis in 5-Hydroxymethylfurfural by Formic Acid over Single-Atom Co-N3/C

“…Inspiringly, the above-mentioned obstacles produced by high-pressure H 2 can be readily overcome via CTH, which allow HMF to be hydrogenated under mild conditions using safer and cheaper hydrogen donors, e.g., formic acid (FA), alcohols, polymethylhydrosiloxane (PMHS), water, and sodium borohydride . Exceptionally, FA behaves as an important byproduct during the acid-catalyzed degradation of carbohydrates to levulinic acid (LA) .…”