Department of Forest Products/Wood Science, Swedish University of Agricultural Sciences , Box 7008, SE-750 07 Uppsala, Sweden.
National Institute of Chemical Physics and Biophysics , Akadeemia tee 23, 12618 Tallinn, Estonia.
Biomacromolecules. 2017 Feb 13;18(2):498-504. doi: 10.1021/acs.biomac.6b01584. Epub 2017 Jan 13.
Fatty acid cellulose esters (FACEs), which have been identified recently as sustainable film materials, are conventionally synthesized by the use of the reaction with acyl chloride/anhydride pyridine in the presence of LiCl/N,N-dimethylacetamide. In this study, we have developed a new synthetic route to FACEs using a vinyl ester of long chain fatty acid, which is an excellent biobased and highly reactive reagent, for the functionalization of cellulose. The developed method involves the synthesis of the long aliphatic fatty acid vinyl ester via a transition-metal-catalyzed transvinylation reaction between vinyl acetate and the fatty acid, followed by its subsequent reaction with cellulose to yield FACEs. In this work, we have used vinyl oleate as a model precursor to introduce the fatty acid chain to cellulose. The covalent grafting of the fatty acid chain to the free hydroxyl groups of cellulose was achieved through potassium carbonate (KCO)-catalyzed transesterification of vinyl oleate in the presence of N-methyl pyrrolidone as solvent with low toxicity. Successful functionalization of cellulose was confirmed by FTIR, C CP-MAS NMR, X-ray diffraction, and the thermogravimetric analysis. The results obtained showed that the functionalization efficiency of the cellulose increased with higher temperature and prolonged reaction times. The strategy proposed in the present work is an important step onward in terms of sustainability because the long-chain vinyl ester can be synthesized from a renewable and biobased source, and the toxic and corrosive chemicals commonly employed for cellulose esterification are avoided.
脂肪酸纤维素酯（FACEs）最近被确定为可持续的薄膜材料，通常是通过酰氯/酸酐吡啶与 LiCl/N，N-二甲基乙酰胺一起反应合成的。在这项研究中，我们开发了一种使用长链脂肪酸的乙烯基酯作为纤维素功能化的新型合成途径。所开发的方法涉及通过过渡金属催化的醋酸乙烯酯和脂肪酸之间的反式乙烯基化反应合成长脂肪族脂肪酸乙烯基酯，然后将其与纤维素反应生成 FACEs。在这项工作中，我们使用油烯基乙烯酯作为模型前体将脂肪酸链引入纤维素。通过在低毒性溶剂 N-甲基吡咯烷酮存在下，用碳酸钾（KCO）催化油烯基乙烯酯的酯交换反应，将脂肪酸链共价接枝到纤维素的游离羟基上。通过傅里叶变换红外光谱（FTIR）、C CP-MAS 核磁共振、X 射线衍射和热重分析证实了纤维素的成功功能化。结果表明，随着温度升高和反应时间延长，纤维素的功能化效率增加。本工作中提出的策略在可持续性方面是重要的一步，因为长链乙烯基酯可以从可再生和生物基来源合成，并且避免了通常用于纤维素酯化的有毒和腐蚀性化学品。
