纤维素在离子液体[AMMor]Cl/[AMIm]Cl混合溶剂中的均相乙酰化反应研究

利用混配离子液体N-烯丙基-N-甲基吗啉氯盐(N-allyl-N-methylmorpholinium chloride,[AMMor]Cl)和1-烯丙基-3-甲基咪唑氯盐(1-allyl-3-methylimidazolium chloride,[AMIm]Cl)作为溶剂,乙酰氯为乙酰化试剂,研究了在没有催化剂条件下的纤维素的均相乙酰化反应.生成的醋酸纤维素(CA)的取代度由2.58到3.00.用FT-IR,1HNMR和13CNMR进行表征.结果表明,[AMMor]Cl/[AMIm]Cl混配的离子液体是一种良好的均相乙酰化介质,纤维素C-6,C-3和C-2三个位置上的羟基均发生了乙酰化反应,且得到纯的纤维素醋酸酯.此反应方便可控,简单高效,不仅降低了成本,离子液体比较容易回收,可以再次利用.     

纤维素醋酸酯的均相合成

纤维素的非均相反应取代不均匀、产率低。本文用纤维素在LiCl／DMAc溶液中的均相反应。制得了纤维素三醋酸酯(CTA)、纤维素二醋酸酯(CDA)、纤维素—醋酸酯(CMA),并对产品结构性能进行了表征。     

高直链淀粉乙酸酯的均相合成及其静电纺丝

离子液体1-烯丙基-3-甲基咪唑氯盐(amimCl)可以有效地溶解高直链淀粉.以amimCl为均相反应介质,在无外加催化剂的存在下一步合成了取代度范围较宽的高直链淀粉乙酸酯.考察了反应时间和酰化试剂用量对酰化程度的影响.不同取代度的酰化淀粉在水、丙酮和DMAc等溶剂中表现出不同的溶解性.进一步对高直链淀粉乙酸酯溶液进行静电纺丝,制备出了由直径在数十至数百纳米、表面光滑、连续的纳米纤维组成的超细纤维多孔膜.     

离子液体二维结构制备及其特性研究进展

由于阴阳离子间特殊的静电、氢键作用, 具有二维结构的离子液体呈现出独特的结构特征及热力学、动力学特性, 在化学化工和材料领域都有着巨大的应用前景, 已成为离子液体领域重要的研究方向之一. 本综述重点介绍了离子液体二维结构常用的制备方法, 包括自组装法、Langmuir-Blodgett法以及物理气相沉积法, 并总结了这些制备方法相应的优缺点. 随后归纳了离子液体二维结构的相变特征及在力学和电学方面的特性, 并综述了其在摩擦润滑领域的应用. 最后展望了离子液体二维结构的发展方向及应用前景.     

CO_2/DBU/DMSO体系中纤维素苯甲酸酯的合成及材料性能研究

基于1,8-二氮杂二环十一碳-7-烯(DBU)存在下,纤维素与CO_2在二甲基亚砜(DMSO)中反应生成纤维素可逆聚离子液体反应的原理,实现纤维素溶解与活化,同时实现原位DBU催化棉浆纤维素与苯甲酸甲酯的转酯化反应,成功制备了不同取代度的纤维素苯甲酸酯.探索了不同反应时间、反应温度、苯甲酸甲酯与纤维素脱水葡萄糖单元(AGU)比例对纤维素取代度的影响,并对纤维素苯甲酸酯进行核磁共振氢谱、碳谱、红外光谱、差示扫描量热法(DSC)、热重分析(TGA)及X射线衍射(XRD)表征.结果表明,转酯化反应温度为115℃,苯甲酸甲酯与AGU比例为5:1,反应24 h时取代度最高能达到0.53.和纤维素相比,纤维素苯甲酸酯有明显的玻璃化转变温度,但其热稳定性下降.     

纤维素在新型绿色溶剂离子液体中的溶解及其应用*

近年来,离子液体作为一种极具应用前景的绿色溶剂受到越来越多的关注。纤维素是自然界中含量最丰富的可再生资源,必将成为未来最重要的工业原料之一。离子液体在纤维素化学领域的应用遵循了绿色化学中开发环境友好溶剂和利用生物可再生资源为原料这两个基本原则,大大拓展了纤维素的工业应用前景,为纤维素资源的绿色应用提供了一个崭新的平台。本文对纤维素在离子液体中溶解的研究进展及其在制备再生纤维素材料、纤维素衍生物及生物乙醇等方面的应用进行了综述。纤维素大分子的降解机理及其控制途径、纤维素晶态结构变化规律及其调控途径、纤维素与固体反应试剂的均相衍生化体系的建立及提高衍生化效率的途径等基础问题仍需要进一步深入研究。     

三种离子液体的合成及其对棉纤维素溶解性能的比较研究

合成了三种含有羧基或醚基的离子液体, 1-羧甲基-3-乙基咪唑氯化物([CmEIM]Cl)、1-甲氧乙基-3-乙基咪唑氯化物([C2OC1-EIM]Cl)和1-[2-(2-氯乙氧基)乙基]-3-乙基咪唑氯化物([Cl-C2OC2-EIM]Cl), 用FT-IR和1H NMR对它们的化学结构进行了表征. 测定并比较了这三种离子液体对棉纤维素的溶解能力, 并用FT-IR, SEM和XRD研究了溶解前和再生后纤维素的化学结构、形貌及晶体结构的变化. 结果表明, 在三种离子液体中, [C2OC1-EIM]Cl对棉纤维素的溶解性最好. 在溶解过程中, 随着温度的升高, 纤维素在离子液体中的溶解度增加, 但聚合度下降, 特别是在[Cl-C2OC2-EIM]Cl中溶解时, 纤维素的聚合度下降最严重. 研究结果表明, 含羧基的离子液体会由于分子间氢键的缔合作用降低其对纤维素的溶解性. 侧基较大的离子液体对纤维素的溶解性也较差.     

羧酸根阴离子型功能化离子液体对纤维素的溶解性能

通过两步法合成了1,3-二甲基咪唑乙酸盐([C₁mim][CH₃COO])和1,3-二甲基咪唑羟基乙酸盐([C₁mim][HOCH₂COO])两种羧酸根阴离子型功能化离子液体。 研究了纤维素在这两种离子液体中的溶解性能。 结果表明,阴离子的结构对纤维素的溶解性能有明显影响,在120 ℃下,两种离子液体对纤维素的溶解度分别为19.7%和21.2%。 通过傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)以及热重分析(TG)等技术手段对再生纤维素的结构和热稳定性进行表征,表明两种离子液体均为纤维素的直接溶剂,纤维素在溶解及再生过程中晶体结构由I型转变为无定型结构,且热稳定性有所下降。 此外,研究发现溶解温度的提高和溶解时间的延长均会导致再生纤维素聚合度的降低。 所获得的研究结果为纤维素溶剂体系的开发具有指导意义。     

离子液体中的纤维素溶解、再生及材料制备研究进展

近年来,离子液体作为一类新型的环境友好介质和软功能材料受到了广泛的关注,并被广泛应用于有机合成、催化、电化学、分离分析等领域.其中,离子液体中的纤维素化学是当前离子液体研究的热点领域之一,离子液体的出现也为纤维素化学的进一步发展提供了广阔的空间.离子液体以其低熔点、高稳定性、低蒸汽压、溶解性能可调节等优异的理化性能已被证实为纤维素的有效溶剂,被广泛用于纤维素的溶解、再生及应用研究.综述了离子液体中纤维素的溶解行为,包括纤维素溶解度的影响因素、纤维素在离子液体中的溶解过程、纤维素的溶解及再生机理等,以及离子液体中基于纤维素的新型材料制备研究进展,并对离子液体中纤维素研究存在的问题和未来的发展方向进行了总结和展望.     

以离子液体为介质的纤维素加工与功能化

纤维素作为自然界中储量最大的天然高分子,被认为是未来世界能源与化工的主要原料.但由于分子链间存在丰富氢键网络以及高度结晶的聚集态结构特点,天然纤维素不熔化、难溶解,造成纤维素的加工极其困难,纤维素材料的传统生产工艺复杂且污染严重,极大限制了纤维素材料的广泛应用.近年来,人们发现一些特定结构的离子液体能够高效溶解纤维素,为纤维素的加工和功能化提供了新的多用途平台.本文从"溶解纤维素的离子液体、纤维素溶解机理与溶液性质、以离子液体制备再生纤维素材料和以离子液体为介质合成纤维素衍生物"4个方面详细介绍了本课题组在此领域的研究进展.     

多环芳二酐型聚酯亚胺膜的透气性能

多环芳二酐型聚酯亚胺膜的透气性能李悦生，丁孟贤，徐纪平（浙江大学高分子科学与工程研究所，杭州，３１００２７）（中国科学院长春应用化学研究所）关键词聚醚酰亚胺，聚酯酰亚胺，膜，透气性通常的聚酰亚胺加工性能较差，在芳环二酐的苯环间引入醚键等柔性基团后，其...     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).     

微量元素与疾病诊断治疗的研究现状及展望

对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述，包括：微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。     

Conformations and steric and stacking interactions of trisubstituted ureas and thioureas with alkyl and phenyl groups

The monomeric ν(N—H) vibrations of various trisubstituted ureas of the R₂UPh type and -thioureas of the R₂TUPh type have been studied. The trans—out isomerism in the former and the trans—out—cis isomerism in the latter are discussed from the point of view of steric effect. The monomeric ν(N—H) vibrations of RPhUPh and RPhTUPh are also examined. The single band appearing in the spectrum of both ureas is characteristic of the cis form; this suggests the existence of phenyl—phenyl interaction (the stacking interaction proposed by Galabov et al. [10]). Behavior of ν(N—H) vibrations at several concentrations is shown to be clearly different in the three forms (trans, out and cis). The presence of the cis form is confirmed by solvent effect experiments.     

Ti-V基储氢合金及其氢化物的物相结构与组分优化设计

Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB₅型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。     

钒与糖代谢及糖尿病

微量元素钒作为生物体内必需元素，经证实有很重要的生理学功能，与机体糖代谢有十分密切的关系，且能降低糖尿病动物模型的高血糖，极有可能被开发为治疗糖尿病的药物。     

Ferrocene and ferrocenium modified clays and their styrene and EVA composites

In this work, ferrocene- and ferrocenium-containing salts were employed to modify montmorillonite. X-ray measurements show an increase in the interlayer spacing upon clay modification, which means that the larger and more organophilic cations were inserted into the gallery space of montmorillonite. Attempts to prepare nanocomposites of polystyrene and ethylene vinyl acetate copolymers lead to immiscible systems; the morphology of these systems was elucidated with TEM, XRD and cone calorimetry. The thermal stability of the composites is greater than that of the virgin polymer.     

Synthesis and Optical and Redox Properties of Symmetric and Asymmetric BODIPYs

Herein, we present the synthetic route and the photophysical, electrochemical as well as laser properties of novel red‐emitting boron‐dipyrromethenes (BODIPYs) bearing arylethyne moieties. Such functionality is added along the main axis of the chromophore leading to single‐ and double‐substituted derivatives. The relationship between the dye structure and the lasing properties is studied in detail with the help of the photophysical and electrochemical properties as well as quantum mechanical simulations. The asymmetric substitution of the parent dye induces inhomogeneities in the charge distribution, which leads to an overall loss of the fluorescence capacity, mainly in polar media. Such non‐radiative deactivation processes can be softened by decreasing the electron‐donor ability of the substituent or even avoided by symmetrical substitution. Thus, grafting of the arylethyne moieties at the longitudinal axis of the indacene core results in an effective strategy to develop red‐edge BODIPYs with highly efficient and photostable laser emission.     

Synthesis of Tyrosol and Hydroxytyrosol Glycofuranosides and Their Biochemical and Biological Activities in Cell-Free and Cellular Assays

Tyrosol (T) and hydroxytyrosol (HOT) and their glycosides are promising candidates for applications in functional food products or in complementary therapy. A series of phenylethanoid glycofuranosides (PEGFs) were synthesized to compare some of their biochemical and biological activities with T and HOT. The optimization of glycosylation promoted by environmentally benign basic zinc carbonate was performed to prepare HOT α-L-arabino-, β-D-apio-, and β-D-ribofuranosides. T and HOT β-D-fructofuranosides, prepared by enzymatic transfructosylation of T and HOT, were also included in the comparative study. The antioxidant capacity and DNA-protective potential of T, HOT, and PEGFs on plasmid DNA were determined using cell-free assays. The DNA-damaging potential of the studied compounds for human hepatoma HepG2 cells and their DNA-protective potential on HepG2 cells against hydrogen peroxide were evaluated using the comet assay. Experiments revealed a spectrum of different activities of the studied compounds. HOT and HOT β-D-fructofuranoside appear to be the best-performing scavengers and protectants of plasmid DNA and HepG2 cells. T and T β-D-fructofuranoside display almost zero or low scavenging/antioxidant activity and protective effects on plasmid DNA or HepG2 cells. The results imply that especially HOT β-D-fructofuranoside and β-D-apiofuranoside could be considered as prospective molecules for the subsequent design of supplements with potential in food and health protection.