Iridium complexes catalysed the selective dehydrogenation of glucose to gluconic acid in water

Abstract

A catalytic dehydrogenation process for the production of gluconic acid from glucose and starch is reported here.

Selective Conversion of Various Monosaccharaides into Sugar Acids by Additive‐Free Dehydrogenation in Water

“…Most probably, cleavage of the diiridium-hydride species provides an iridium monohydride intermediate, which is able to bind the carbohydrate or water and subsequently release a carbohydrate/water proton and the metal-bound hydride as H2. A plausible mechanism for the conversion of sugars into sugar acids is proposed based on previous results [29] and complemented by the new experimental evidence from this work (Scheme 2). Iridium complexes of general formula [Cp*IrL(Cl)2] (L = NHC or triazolylidene undergo water/halide ligand exchange forming the aqua complexes that are the active catalytic species (Scheme 1).…”

“…In preliminary work, we demonstrated the formation of gluconic acid using homogeneous Cp*Ir complexes with imidazole-based N-heterocyclic carbene (NHC) ligands. [29] This transformation is formally an oxidation of glucose but is better described as a dehydrogenative coupling of glucose and water with the simultaneous formation of molecular hydrogen. Starting from glucose, the process is highly selective towards the formation of gluconic acid but requires strong acidic conditions.…”

Oxidant-Free Transformation of Ethylene Glycol toward Glycolic Acid in Water

“…After six times, the conversion of EG marginally declines from 97.5% to 85.8%; meanwhile, the GA yield undergoes a similar process, Finally, the conversions of biomass-derived sugars are also studied to further investigate the applicability of this transformation route. In the previous reports, 37,38 the dehydrogenation reactions catalyzed by transition metal complexes were applied to the preparation of sugar lactones and acid from sugar in organic solvents or water, and no C−C bond breaking was involved. Herein, to preferentially drive their C−C splitting, the reaction temperature is raised to 170 °C.…”

Fe3O4@GlcA@Cu-MOF: A Magnetic Metal–Organic Framework as a Recoverable Catalyst for the Hydration of Nitriles and Reduction of Isothiocyanates, Isocyanates, and Isocyanides

“…Besides, the recovered nanocatalysts were applied for at least four times. Refs , , , , , , , , , , , and .…”