Acetalization strategy in biomass valorization: a review

Acetalization represents an appealing approach for the valorization of biobased platform molecules into valuable chemicals and fuels. Typically, it serves as both a synthesis tool for renewable cyclic acetals and a protection strategy to improve selectivity in biomass conversion. This contribution provides an overview on the application of the acetalization strategy in biomass valorization including synthesis of cyclic acetal fuel additives from the acetalization of biobased furanic compounds with biogenic ethylene glycol/glycerol and acetalization as a protection approach to improve product selectivity in biomass valorization. The latest progresses in the development of catalytic systems for the acetalization of biobased furanic compounds and biogenic ethylene glycol/glycerol are systematically summarized and discussed, with an emphasis on the reaction pathway, relationship between catalyst structures and their performance, and relevant catalytic mechanism. Moreover, the application of the acetalization strategy for protecting carbonyl groups/diol structure functionalities to improve the target products' selectivity in lignin depolymerization, 5-hydroxymethylfurfural oxidation, sorbitol dehydration, and xylose hydrogenation is also highlighted. Eventually, the prospects and challenges in the synthesis of cyclic acetal fuel additives as well as applying acetalization as a protection strategy in biomass valorization are outlined.

Keywords: Oxygenated fuel additives; Furanic compounds; Bioalcohols; Acetalization; Chemocatalysis.