The elucidation of the ring-opening reaction mechanism is a critical step towards improving the catalytic performance for the conversion of biomass into value-added chemicals. Herein, we focused on the stepwise C–O bond hydrogenolysis mechanism of oxygen-containing heterocycles (O-heterocycles) into α,ω-diols, in particular THFA to 1,5-PeD, over selective Ni-La(OH)3 in hydrogen-donor isopropanol. A mechanistic study was carried out on a structurally well-defined Ni-La(OH)3, where the mechanism was elucidated using a combination of kinetic and 13C NMR isotope labeling experiments. It was suggested that both Ni nanoparticles and La(OH)3 support play a critical role in the reaction mechanism, where basic hydroxide species of the support initially deprotonate the CH2OH and –OH modified furan, tetrahydrofuran and tetrahydropyran rings, adsorbing them chemically on the catalyst surface. This step is followed by a direct hydride attack on the second carbon atom of these rings, which is proposed to be the key step for ring cleavage, as indicated by the increased deuteration at this position. It is assumed that a catalytic transfer hydrogenolysis reaction (CTH) reaction of THFA is proposed to proceed via the dehydrogenation of isopropanol over isolated Ni species, forming hydrogen species that can be adsorbed on the Ni surface or desorb as H2.

In this work, highly efficient carbon-supported Pd-based catalysts for formic acid dehydrogenation were synthesized by a straightforward wet impregnation-reduction method. The carbon support was obtained from a biomass residue (almond shell) prepared via H3PO4-assisted hydrothermal carbonization (HTC) and thermal activation. This carbon support was doped with nitrogen groups to study the effect on the electronic properties and catalytic performance of the catalysts. Investigating the formation of PdAg alloys with varying Pd:Ag molar ratios resulted in catalysts exhibiting enhanced catalytic activity compared to monometallic Pd counterparts. Notably, the Pd1Ag0.5/NAS catalyst displayed outstanding catalytic performance, achieving an initial TOF of 1716 h-1 (calculated in the first 3 minutes of reaction and expressed per mole of Pd) and maintaining substantial activity over 6 consecutive reaction cycles. This work elucidates the successful synthesis of effective catalysts, emphasizing the influence of nitrogen doping and PdAg alloy composition on catalytic behavior and stability.

Carboligases catalyze the thiamine diphosphate (ThDP) dependent formation of carbon-carbon bonds. These enzymes are prominent biocatalysts for the production of valuable a-hydroxy carbonyl compounds, which serve as key building blocks in the synthesis of various pharmaceuticals and fine chemicals. Carboligases act in selective manner to afford regio- and stereochemically defined products from simple starting materials. This review explores the catalytic prowess of carboligases for synthetic purposes and is aimed at providing a selection tool of enzymes for particular sets of substrates or desired products. The comprehensive overview encompasses structural insights, relationships of the currently known sequence space and practical applications with a focus on recent literature, showcasing carboligases as potent tools for sustainable and efficient synthesis.