Rh-Catalyzed Hydrogenation of Amino Acids to Biobased Amino Alcohols: Tackling Challenging Substrates and Application to Protein Hydrolysates

Abstract

While protein-rich biomass waste is nowadays mainly used for animal feed, conversion of its amino acid constituents to nitrogenous chemicals is a potential higher value route. To that end, the hydrogenation of amino acids to amino alcohols was studied in this work. Using a bimetallic Rh-MoOx/SiO2 catalyst, glutamic acid was for the first time hydrogenated to the aminodiol in high yield. By minimizing partial reduction and consecutive hydrogenolysis, and by suppressing the competitive cyclization to pyroglutamic acid (and derivatives thereof), glutamidiol was obtained in 77% yield at 70 bar H2 and 80 °C. High yields (typically > 80%) and selectivities were also achieved for most other natural amino acids, except for the S-containing amino acids 2 cysteine and methionine, which act as catalyst poisons. This limitation was overcome by applying a simple oxidation step with performic acid prior to the hydrogenation. The system was applied successfully to a mixture of amino acids obtained by hydrolysis of pre-oxidized bovine serum albumin. Amino alcohols were produced with high overall conversion (> 90%) and selectivity (88%) without the need for an intermediate, expensive and difficult separation step. The reaction proceeds with very high atom economies for both carbon and nitrogen, and generates only water as a by-product.

Protein‐Rich Biomass Waste as a Resource for Future Biorefineries: State of the Art, Challenges, and Opportunities

“…Moreover, the aromatic moieties in phenylalanine and tyrosine were completely reduced to their saturated analogs, but this side reaction has been observed for Ru‐based catalysts as well . Poisoning of the Rh catalyst by cysteine and methionine was avoided by applying an oxidative pretreatment with performic acid, to convert the S‐containing thiol and thioether groups into inert sulfonic acid and sulfone groups, which do not possess lone pairs anymore …”

Pd nanoparticles on green support as dip-catalyst: a facile transfer hydrogenation of olefins and N-heteroarenes in water

“…Transition metal-mediated hydrogenation 1,2 using Fe, 3 Co, 4 Ni, 5 Pd, 6,7 Pt, 8 Rh, 9,10 Ir, 11 Ru 12 or Mo 13 is a well-established procedure in research and industrial applications. However, this approach usually requires high hydrogen pressure, resulting in over reduction or functional group intolerance of the substrate.…”

Resource Upgrading in Advanced Supercritical Fluid (Supercritical Fluid with Catalyst and Cosolvent): Liquid Fuels from Biomass in Sub and Supercritical Water and Carbohydrate Up-Conversion in Ionic Liquid and Supercritical Fluids Mixtures

“…It was reported that Pt/TiO 2 promotes the reductive deamination of glutamic acid derivatives to form organic acids at 225°C for 24 h [54]. By the same research group of [54], decarbonylation of amino acids was attempted by Ru-based catalyst [55]. Reductive (hydrogenation) decarbonylation of valine to isobutylamine was developed in the presence of Ru-catalyst with isobutylamine yield of 87% in hydrothermal water at 150°C for 2 h.…”