Biomass, which is mainly composed of lignocellulose and vegetable oil, is recognized as one of the most promising sustainable sources of carbon raw material for the synthesis of transportation fuels and value-added chemicals. The catalytic conversion of lignocellulose/vegetable oil and their related derivatives has attracted much attention in biomass valorization.
Many elegant methods including hydrolysis, dehydration, hydrogenation, hydrogenolysis, oxidation, etherification, esterification, amination, aldol condensation, Diels-Alder, Knoevenagel condensation, and acetalization have been developed for the valorization of lignocellulose/vegetable oil derivatives to value- added chemicals and biofuels.
In particular, acetalization is highlighted as an attractive method of biomass valorization because it serves as a synthesis tool for renewable acetal fuel additives and a protection strategy to improve product selectivity. A group of scientists summarized the latest developments regarding the use of the acetalization strategy in biomass valorization. Their work was published in Industrial Chemistry & Materials.
“The development of efficient and selective strategies is essential for the balancing of lignocellulose/vegetable oil derivatives,” said Changzhi Li, a Professor at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, “In this review, we systematically discuss the recent development of the application of acetalization strategy in biomass valorization.”
“The latest progress in the development of catalytic systems for the acetalization of biobased furanic compounds and biogenic ethylene glycol/glycerol is systematically summarized and discussed, with emphasis on the reaction pathway, relationship between catalyst structures and their performance, and related catalytic mechanism.”
“In addition, the use of the acetalization strategy for the protection of carbonyl groups/diol functional groups to improve the selectivity of target products in lignin depolymerization, 5-hydroxymethylfurfural oxidation, sorbitol dehydration, and xylose hydrogenation is highlighted. . We also provide an overview of the remaining challenges in this field.”
“Acetalization, a well-known reversible reaction between carbonyl compounds and alcohols, usually requires more than one of the reactants to force the reversible acetalization to completion,” Li said.
“However, studies on the recovery of the excess reaction after the reaction are scarce. In addition, the separation and purification of cyclic acetals / ketals should be paid more attention. the excess substrate and/or product separation of acetals. ”
“A five-membered ring acetal (ie, 1,3-dioxolane) and a six-membered ring acetal (ie, 1,3-dioxane) are obtained from the acetalization of a furanic compound and glycerol,” said Li, ” However, it is a significant challenge to achieve the selective synthesis of 1,3-dioxolane or 1,3-dioxane. 1,3-dioxane.”
“In addition, the use of crude glycerol, which comes from the production of biodiesel, for acetalization is more economically viable, and the influence of impurities in the acetalization reaction should be investigated.”
Currently, available researches for obtaining insights into the detailed catalytic mechanism for the acetalization of furanic compounds and ethylene glycol/glycerol are limited. Further effort should be devoted to the fundamental understanding of the catalytic mechanism through in situ spectroscopic measurements and density functional theory calculations.
“The synthesis of a product with high selectivity during the valorization of biomass derivatives is very difficult due to the presence of many functional groups (for example, C = O, C = C, and CO) in biomass molecules, said Li.
“Taking advantage of the fact that acetalization is a reversible reaction and the formed cyclic acetals/ketals are stable/low reactivity in basic media, acetalization as a strategy to protect the carbonyl group is the value of further promotion of biomass valorization such as the exclusive hydrogenation of C. = C in the biobased multifunctional compound while leaving the C = O group unreduced.
“In this review, our main goal is to provide readers with timely and accurate research progress on the use of acetalization strategy in biomass valorization,” said Li.
Jian He et al, Acetalization strategy in biomass valorization: a review, Industrial Chemistry & Materials (2023). DOI: 10.1039/D3IM00050H
Provided by Industrial Chemistry & Materials
Citation: Acetalization: A feasible and sustainable strategy for biomass valorization (2023, July 19) retrieved 19 July 2023 from https://phys.org/news/2023-07-acetalization-feasible-sustainable-strategy-biomass .html
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