Catalytic Hydrogenation of Carboxylic Acids

The catalytic hydrogenation of carboxylic acids—the reduction of R–COOH functionalities to alcohols or hydrocarbons under a hydrogen atmosphere—stands at the interface of sustainable chemistry and industrial synthesis. Owing to the intrinsic thermodynamic stability of the carboxyl group and the tendency for decarbonylation side‐reactions, this transformation traditionally requires harsh temperatures and pressures. Recent advances have focused on the design of catalysts that combine high activity with selectivity, enabling milder reaction conditions and broader substrate scope. Homogeneous systems based on late‐transition‐metal complexes exploit metal–ligand cooperation to activate both hydrogen and the acid substrate, while heterogeneous catalysts—ranging from supported noble metals to bimetallic alloys of earth-abundant metals—leverage support effects and surface ensemble engineering. Key challenges include suppression of undesired pathways (notably CO formation), improvement of catalyst robustness in aqueous or biomass-derived feedstocks, and scale-up for the production of green fuels, fine chemicals and pharmaceutical intermediates. Technological innovations in catalyst architecture, reactor design and mechanistic understanding continue to drive this field towards global sustainability goals.

Research from Nature Portfolio

Recent studies have showcased the potential of base-metal catalysts for chemoselective hydrogenation of carboxylic acids under near-ambient conditions. In one report, nickel–copper bimetallic nanoparticles supported on oxide frameworks achieved high turnover numbers for the reduction of diverse aliphatic and aromatic acids to the corresponding alcohols, with water as the only by-product. Mechanistic investigations revealed cooperative hydrogen activation at metal–metal interfaces and proton shuttling via surface hydroxyls. Another work described a ruthenium‐complex bearing a proton-responsive ligand that mediates intramolecular hydrogen transfer, enabling the hydrogenation of sterically hindered dicarboxylic acids at temperatures below 100 °C. This system illustrated how fine tuning of metal–ligand interactions can suppress decarbonylation and improve catalyst longevity in aqueous media.

Catalytic Hydrogenation of Carboxylic Acids publication trend

The graph below shows the total number of articles in catalytic hydrogenation of carboxylic acids across all publications each year (not limited to Nature Index journals).

Technical terms

Carboxylic acid: organic compound featuring a –COOH group, susceptible to reduction to alcohols or hydrocarbons.

Catalytic hydrogenation: a reaction in which a catalyst promotes the addition of hydrogen (H₂) across unsaturated bonds.

Hydrodeoxygenation: removal of oxygen atoms from organic substrates via hydrogenolysis.

Decarbonylation: cleavage of C–C bonds adjacent to carbonyl groups, often yielding CO and hydrocarbon fragments.

Metal–ligand cooperation: synergistic interaction between a metal centre and a coordinated ligand that facilitates substrate activation.

Heterogeneous catalyst: a solid catalyst whose active sites are distinct from the phase of the reactants, offering ease of separation and reuse.

References

1. Effect of Sn Addition in Gas Phase Hydrogenation of Acetic Acid on Alumina Supported PtSn Catalysts. Catalysis Letters (2014).
2. Kinetic and Mechanistic Analysis of the Hydrodeoxygenation of Propanoic Acid on Pt/SiO2. Industrial & Engineering Chemistry Research (2021).