木素模型化合物在离子液体—水中溶解行为的光谱研究
发布时间：2019-03-21 16:59
【摘要】：本课题组利用离子液体-水体系对木质素进行溶解,但溶解机理尚不明确,这在一定程度上限制了离子液体-水-木质素体系的深层次研究。由于木质素是一种天然高分子聚合物,含有复杂的官能团和空间结构,要考察其与离子液体水之间的相互作用行为比较困难。我们以木素模型化合物2,6-二甲氧基苯酚(2,6-DMP)为探针,研究其在离子液体-水体系中的溶解规律,通过光谱手段解析木素模型化合物、离子液体、水三者之间分子相互作用。从而为木质素的溶解机制提供合理的理论基础。本论文研究主要内容包括:1、配制不同种类、不同浓度离子液体水溶液,选定2,6-DMP为简单酚型木素模型化物,并测定其在特定不同摩尔分数离子液体水溶液中的溶解度。2、固定离子液体与2,6-DMP的摩尔比例(1:0.4),利用谱学手段考察分子间相互作用力。如衰减全反射红外光谱(ATR-IR),二维相关红外光谱,拉曼光谱来考察不同浓度离子液体水溶液中离子液体和水的存在形态及2,6-DMP加入后,三元体系中水簇集体和离子液体聚集体的变化。3、由溶解度在不同摩尔分数离子液体水中的不同现象,解释2,6-DMP的溶解机理,预测木质素在不同离子液体水体系下的溶解特性。通过实验分析,得到以下结论:1.利用衰减全反射红外光谱(ATR-IR)研究2,6-DMP在1-丁基-3-甲基咪唑四氟硼酸盐([C4mim]BF4)水溶液(离子液体摩尔分数xIL=1.0-0.02)中的溶解行为。随着水的加入,2,6-DMP溶解度先增大而后减小,对应的xIL阈值为0.1。ATR-IR和二维相关红外分析结果表明,随着加入水量增大,水能破坏[C4mim]BF4离子簇结构,使其转变为离子对,这种微观聚集状态变化影响2,6-DMP溶解行为。2.利用拉曼光谱对烷基咪唑溴盐-水-木质素模型化合物2,6-DMP三元体系和烷基咪唑溴盐-水二元体系进行分析和比较。发现咪唑环和烷基侧链与水、2,6-DMP之间存在分子间相互作用。离子液体烷基链的顺反构型不同,1-乙基-3-甲基咪唑溴盐([Emim]Br)的烷基侧链为邻位交叉式构型,而1-己基-3-甲基咪唑溴([Hmim]Br)存在反式和邻位交叉式顺反异构体。在富水区域[Hmim]Br的顺反异构体会受大分子水簇影响,而2,6-DMP的加入不会对离子液体烷基链构型的变化有影响。
[Abstract]:The dissolution mechanism of lignin by ionic liquid-water system is not clear, which limits the deep study of ionic liquid-water-lignin system to a certain extent. As lignin is a natural polymer containing complex functional groups and spatial structure, it is difficult to investigate the interaction between lignin and ionic liquid water. We used lignin model compound 2,6-dimethoxyphenol (2,6-dimethoxyphenol) as probe to study its dissolution in ionic liquid-water system. Water interacts with molecules. Therefore, it provides a reasonable theoretical basis for the dissolution mechanism of lignin. The main contents of this thesis are as follows: 1. Different kinds of ionic liquids and different concentrations of aqueous solutions were prepared, and 2,6 DMP were selected as simple phenolic lignin model compounds. The solubility of the ionic liquid in aqueous solution with different molar fraction was measured. 2. The molar ratio of the fixed ionic liquid to 2,6-DMP (1? 0.4) was determined. The intermolecular interaction force was investigated by spectroscopic method. For example, attenuated total reflection infrared spectroscopy (ATR-IR), two-dimensional correlation infrared spectroscopy and Raman spectroscopy were used to investigate the morphology of ionic liquids and water in aqueous solutions with different concentrations of ionic liquids and the addition of 2,6-DMP. Changes in water clusters and ionic liquid aggregates in ternary systems. 3. The dissolution mechanism of 2,6-DMP is explained by the different phenomena of solubility in ionic liquid water with different molar fractions. The dissolution characteristics of lignin in different ionic liquid water systems were predicted. Through the experimental analysis, the following conclusions are obtained: 1. The dissolution behavior of 2,6-DMP in 1-Ding Ji-3-methylimidazolium tetrafluoroborate ([C4mim] BF4) aqueous solution (ionic liquid mole fraction xIL=1.0-0.02) was studied by attenuated total reflection infrared spectroscopy (ATR-IR). With the addition of water, the solubility of 2,6-DMP increases first and then decreases. The corresponding xIL thresholds are 0.1.ATR-IR and two-dimensional correlation infrared analysis. The results show that the structure of [C4mim] BF4 ion cluster is destroyed by water energy with the increase of water content. The change of the micro-aggregation state affects the dissolution behavior of 2, 6-DMP. 2. The ternary system of alkylimidazole bromide-water-lignin model compound 2,6-DMP and alkylimidazole-water binary system were analyzed and compared by Raman spectroscopy. It was found that there was an intermolecular interaction between imidazole ring and alkyl side chain and water, 2,6, DMP. The alkyl side chains of 1-ethyl-3-methylimidazolium bromide ([Emim] Br) are ortho-cross configuration. However, 1-hexyl-3-methylimidazolium bromide ([Hmim] Br) has trans and ortho-cross cis-trans isomers. The cis-trans isomerization of [Hmim] Br in the water-rich region is affected by macromolecular water clusters, while the addition of 2,6-DMP has no effect on the configuration of alkyl chains in ionic liquids.
【学位授予单位】：大连工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O645.1;O636.2
本文编号：2445131
[Abstract]:The dissolution mechanism of lignin by ionic liquid-water system is not clear, which limits the deep study of ionic liquid-water-lignin system to a certain extent. As lignin is a natural polymer containing complex functional groups and spatial structure, it is difficult to investigate the interaction between lignin and ionic liquid water. We used lignin model compound 2,6-dimethoxyphenol (2,6-dimethoxyphenol) as probe to study its dissolution in ionic liquid-water system. Water interacts with molecules. Therefore, it provides a reasonable theoretical basis for the dissolution mechanism of lignin. The main contents of this thesis are as follows: 1. Different kinds of ionic liquids and different concentrations of aqueous solutions were prepared, and 2,6 DMP were selected as simple phenolic lignin model compounds. The solubility of the ionic liquid in aqueous solution with different molar fraction was measured. 2. The molar ratio of the fixed ionic liquid to 2,6-DMP (1? 0.4) was determined. The intermolecular interaction force was investigated by spectroscopic method. For example, attenuated total reflection infrared spectroscopy (ATR-IR), two-dimensional correlation infrared spectroscopy and Raman spectroscopy were used to investigate the morphology of ionic liquids and water in aqueous solutions with different concentrations of ionic liquids and the addition of 2,6-DMP. Changes in water clusters and ionic liquid aggregates in ternary systems. 3. The dissolution mechanism of 2,6-DMP is explained by the different phenomena of solubility in ionic liquid water with different molar fractions. The dissolution characteristics of lignin in different ionic liquid water systems were predicted. Through the experimental analysis, the following conclusions are obtained: 1. The dissolution behavior of 2,6-DMP in 1-Ding Ji-3-methylimidazolium tetrafluoroborate ([C4mim] BF4) aqueous solution (ionic liquid mole fraction xIL=1.0-0.02) was studied by attenuated total reflection infrared spectroscopy (ATR-IR). With the addition of water, the solubility of 2,6-DMP increases first and then decreases. The corresponding xIL thresholds are 0.1.ATR-IR and two-dimensional correlation infrared analysis. The results show that the structure of [C4mim] BF4 ion cluster is destroyed by water energy with the increase of water content. The change of the micro-aggregation state affects the dissolution behavior of 2, 6-DMP. 2. The ternary system of alkylimidazole bromide-water-lignin model compound 2,6-DMP and alkylimidazole-water binary system were analyzed and compared by Raman spectroscopy. It was found that there was an intermolecular interaction between imidazole ring and alkyl side chain and water, 2,6, DMP. The alkyl side chains of 1-ethyl-3-methylimidazolium bromide ([Emim] Br) are ortho-cross configuration. However, 1-hexyl-3-methylimidazolium bromide ([Hmim] Br) has trans and ortho-cross cis-trans isomers. The cis-trans isomerization of [Hmim] Br in the water-rich region is affected by macromolecular water clusters, while the addition of 2,6-DMP has no effect on the configuration of alkyl chains in ionic liquids.
【学位授予单位】：大连工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O645.1;O636.2
【参考文献】
相关期刊论文 前1条
1 郑大锋,邱学青,楼宏铭;木质素的结构及其化学改性进展[J];精细化工;2005年04期
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