Thermochemical Conversion of Wheat Straw Dioxane Lignin in a Sub/Supercritical Dimethyl Carbonate Medium

IF 1.1 4区 化学 Q4 BIOCHEMISTRY & MOLECULAR BIOLOGY
S. S. Shashkina, N. P. Tiguntseva, S. N. Evstaf’ev
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Abstract

Objective: The main goal of this study was to investigate the thermochemical conversion of wheat straw dioxane lignin in a sub/supercritical dimethyl carbonate medium. The object of our study was the dioxane lignin isolated from wheat straw. The conversion of wheat straw dioxane lignin in a sub/supercritical dimethyl carbonate medium was studied. Methods: The experiment was performed in an autoclave in a temperature range from 200°C to 350°C. The low-molecular-weight products were extracted from the liquid fraction using hexane; GC-MS was used to study their composition. The solid products were analyzed by IR spectroscopy. Results and Discussion: The low-molecular-weight products consist of esters, aldehydes, ketones, and alkyl aromatic compounds. Thirty-four compounds were identified by GC-MS, including 12 C6–C3 compounds, i.e., those whose structures match the generally recognized phenylpropane unit of lignin. The low-molecular-weight products fraction is predominantly comprised of methyl esters of aromatic and fatty acids. More than 95% of the identified low-molecular-weight products are veratric-type compounds. New data on the conversion undergone by the wheat straw dioxane lignin in a sub/supercritical dimethyl carbonate medium were obtained. It was shown that high solubility of dioxane lignin under subcritical conditions may be due to cleavage of intermolecular interaction, including hydrogen bonds between the dioxane lignin macromolecules, as a result of thermal exposure and methylation reactions. Fragmentation of the dioxane lignin macromolecules under supercritical conditions involves the processes of radical cleavage of the alkyl aryl ether bonds, as well as the dealkylation, dehydration, methylation, transesterification, and demetoxylation reactions. Conclusions: New data on the conversion of wheat straw dioxane lignin in a sub/supercritical dimethyl carbonate medium were obtained.

Abstract Image

麦草二氧环木质素在亚/超临界碳酸二甲酯介质中的热化学转化
目的:研究麦草二氧环木质素在亚/超临界碳酸二甲酯介质中的热化学转化。以麦草为原料分离得到二氧六环木质素为研究对象。研究了在亚/超临界碳酸二甲酯介质中麦草二氧环木质素的转化。方法:实验在高压灭菌器中进行,温度范围从200°C到350°C。液体馏分用己烷萃取低分子量产物;采用气相色谱-质谱法对其组成进行了研究。用红外光谱对固体产物进行了分析。结果与讨论:低分子量产物由酯类、醛类、酮类和烷基芳香族化合物组成。GC-MS鉴定了34个化合物,其中C6-C3化合物12个,即结构与木质素中公认的苯丙烷单元相匹配的化合物。低分子量产物部分主要由芳香族脂肪酸甲酯和脂肪酸甲酯组成。95%以上已鉴定的低分子量产物为杂环型化合物。获得了麦草二氧环木质素在亚/超临界碳酸二甲酯介质中转化的新数据。结果表明,二氧六环木质素在亚临界条件下的高溶解度可能是由于热暴露和甲基化反应导致分子间相互作用(包括二氧六环木质素大分子之间的氢键)的断裂。二氧六环木质素大分子在超临界条件下的断裂过程包括烷基芳基醚键的自由基裂解,以及脱烷基、脱水、甲基化、酯交换和去甲氧基化反应。结论:获得了在亚/超临界碳酸二甲酯介质中麦草二氧环木质素转化的新数据。
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来源期刊
Russian Journal of Bioorganic Chemistry
Russian Journal of Bioorganic Chemistry 生物-生化与分子生物学
CiteScore
1.80
自引率
10.00%
发文量
118
审稿时长
3 months
期刊介绍: Russian Journal of Bioorganic Chemistry publishes reviews and original experimental and theoretical studies on the structure, function, structure–activity relationships, and synthesis of biopolymers, such as proteins, nucleic acids, polysaccharides, mixed biopolymers, and their complexes, and low-molecular-weight biologically active compounds (peptides, sugars, lipids, antibiotics, etc.). The journal also covers selected aspects of neuro- and immunochemistry, biotechnology, and ecology.
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