Aldehyde Electrophilicity and Ring Strain Govern Xylose Acetalization Pathways for Biobased Chemical Production

Abstract

Xylose acetalization has emerged as a potent tool to extract this sugar from lignocellulosic biomass and for creating new biobased chemicals and materials. This article elucidates a generalized reaction network for xylose acetalization and reveals the role of aldehyde electrophilicity and ring strain in intermediate formation. Aldehydes with strong electrophilicity stabilize xylose as both furanose- and pyranose-monoacetals, whereas weaker aldehydes favour xylofuranose acetalization due to the high ring strain in pyranose acetals. The energetically favoured furanose diacetals dominate the product distribution over extended reaction time regardless of aldehyde types and reaction pathways. Measurements of the xylose tautomer ratio in the reaction conditions highlighted the importance of xylose isomerization in forming furanose acetals. These mechanistic insights not only explain the evolution of reaction intermediates but also aid in identifying potential products for sustainable chemical synthesis.