Understanding the role of the substrate and the metal triflate acidic catalyst in sugar platform biorefineries: A comprehensive systematic approach to catalytic transformations of (poly)carbohydrates in ethanol

Abstract

We systematically explore a range of model conversions of mono- and disaccharides, and of linear and branched polysaccharides under the catalytic action of metal trifluoromethanesulfonates (metal triflates) in ethanol. This highlights the preferred reactivity of specific (poly)carbohydrates, and the interplay between selectivities of the reactions and the dominating catalyst activity (Brønsted or Lewis). It unambiguously delineates that selectivities of acid-catalysed transformations of (poly)carbohydrates into value added platform chemicals rely on the origin of the substrate, any (pre)treatment, the acidic catalyst, and the reaction conditions. The optimised catalytic systems enable very efficient conversion of cellulosic carbohydrates into significantly value added ethyl glucosides (yields up to 63%), ethyl xylosides (yields up to 69%), ethyl levulinate (yields up to 75%), ethyl lactate (yields up to 98%), ethoxyacetaldehyde diethylacetal (yields up to 33%), and furfural diethylacetal (yields up to 44%), depending on the substrate and reaction conditions.