Base-free trifluoroacetylation: From methyl glucopyranoside to cellulose nanofibers

IF 2.4 3区化学 Q3 BIOCHEMISTRY & MOLECULAR BIOLOGY

Carbohydrate Research Pub Date : 2024-09-24 DOI:10.1016/j.carres.2024.109282

Robert J. Nicholas, Nosa B. Idahagbon, Alexander Wei

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引用次数: 0

Abstract

Trifluoroacetic anhydride (TFAA) reacts smoothly with low molecular weight carbohydrates and cellulose nanofibers (CNFs) under base-free conditions. Methyl α- and β-d-glucopyranoside were used as model compounds to optimize reaction conditions, which were then applied to lyophilized CNFs for surface modification. ATR-IR spectroscopy and powder X-ray diffraction were employed to characterize the modified CNFs. Trifluoroacetylation for 4 h yields a degree of substitution (DS) of 0.4 acyl groups per anhydroglucose unit while maintaining a crystallinity index near 50 %. DS values were quantified by gravimetry, acid–base titration after saponification, and a novel approach utilizing solution ¹⁹F NMR spectroscopy which offers greater accuracy than the other techniques. This study presents an efficient, base-free method for derivatizing carbohydrates as well as surface functionalization of CNFs with trifluoroacetyl groups, potentially expanding their application in fiber-reinforced thermoplastic composites.

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无碱三氟乙酰化：从甲基吡喃葡萄糖苷到纤维素纳米纤维

三氟乙酸酐（TFAA）可在无碱条件下与低分子量碳水化合物和纤维素纳米纤维（CNF）顺利反应。以甲基α-和β-d-吡喃葡萄糖苷为模型化合物优化反应条件，然后将其应用于冻干的 CNFs 进行表面改性。采用 ATR-IR 光谱和粉末 X 射线衍射来表征改性后的 CNF。三氟乙酰化 4 小时后，每个脱水葡萄糖单位的酰基取代度（DS）为 0.4，同时结晶度指数保持在 50% 附近。DS 值的定量方法有：重量测量法、皂化后的酸碱滴定法，以及一种利用溶液 19F NMR 光谱的新方法，后者比其他技术更精确。这项研究提出了一种高效、无碱的方法来衍生碳水化合物，并用三氟乙酰基对 CNFs 进行表面官能化，从而有可能扩大其在纤维增强热塑性复合材料中的应用。

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来源期刊

Carbohydrate Research 化学-生化与分子生物学

CiteScore

5.00

自引率

3.20%

发文量

183

审稿时长

3.6 weeks

期刊介绍： Carbohydrate Research publishes reports of original research in the following areas of carbohydrate science: action of enzymes, analytical chemistry, biochemistry (biosynthesis, degradation, structural and functional biochemistry, conformation, molecular recognition, enzyme mechanisms, carbohydrate-processing enzymes, including glycosidases and glycosyltransferases), chemical synthesis, isolation of natural products, physicochemical studies, reactions and their mechanisms, the study of structures and stereochemistry, and technological aspects. Papers on polysaccharides should have a "molecular" component; that is a paper on new or modified polysaccharides should include structural information and characterization in addition to the usual studies of rheological properties and the like. A paper on a new, naturally occurring polysaccharide should include structural information, defining monosaccharide components and linkage sequence. Papers devoted wholly or partly to X-ray crystallographic studies, or to computational aspects (molecular mechanics or molecular orbital calculations, simulations via molecular dynamics), will be considered if they meet certain criteria. For computational papers the requirements are that the methods used be specified in sufficient detail to permit replication of the results, and that the conclusions be shown to have relevance to experimental observations - the authors'' own data or data from the literature. Specific directions for the presentation of X-ray data are given below under Results and "discussion".