Insights into the borohydride reduction of dialdehyde cellulose: the dilemma of competing reduction and β-elimination reactions

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2023-09
Major/Subject
Mcode
Degree programme
Language
en
Pages
16
8205-8220
Series
Cellulose, Volume 30, issue 13
Abstract
Borohydride reduction of dialdehyde cellulose (DAC) is a promising strategy to generate dialcohol cellulose as bio-based alternative to petroleum-based materials. However, the degradation of the polymer backbone according to β-elimination mechanisms limits the practical applications of the reaction. Therefore, we aimed at optimizing the process to suppress degradation reactions by varying reaction time, pH, and reagent stoichiometry. The degree of oxidation (DO) of the DAC intermediates significantly impacts the yields and molecular weights of the isolated dialcohol celluloses, with a “leveling-off” effect at higher DO values. Increasing the amount of sodium borohydride can minimize—but not entirely prevent—chain scissions. Lowering the pH value during reduction slows down the degradation but results in incomplete conversion of the aldehyde functionalities. Our study provides valuable insights into the consequences of side reactions during borohydride reduction of DAC as well as into chemistry and analysis ofthe dialdehyde cellulose/dialcohol cellulose system. Graphical abstract: About a dilemma in cellulose chemistry: Dialcohol cellulose derived by periodate oxidation and subsequent borohydride reduction of cellulose has received increasing attention in the development of sustainable thermoplastic materials. The present study highlights the challenge of suppressing β-elimination and favoring the reduction pathway to optimize reaction conditions and minimize chain degradation.
Description
Funding Information: Open access funding provided by University of Natural Resources and Life Sciences Vienna (BOKU). The financial support by Business Finland, UPMKymmene Oyj (Finland), the Austrian Biorefinery Center Tulln (ABCT), and the doctoral school “Advanced Biorefineries: Chemistry & Materials” (ABC&M) is gratefully acknowledged. Publisher Copyright: © 2023, The Author(s).
Keywords
Cellulose, Dialdehyde cellulose, Gel permeation chromatography, Periodate oxidation, Reduction, Renewable resources, “Level-off” DP
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Citation
Simon , J , Fliri , L , Fröhlich , F , Sapkota , J , Ristolainen , M , Hummel , M , Rosenau , T & Potthast , A 2023 , ' Insights into the borohydride reduction of dialdehyde cellulose: the dilemma of competing reduction and β-elimination reactions ' , Cellulose , vol. 30 , no. 13 , pp. 8205-8220 . https://doi.org/10.1007/s10570-023-05350-1