低共熔溶剂的应用研究现状

低共熔溶剂是两种或多种固体或液体物质通过氢键相互作用形成的液体溶剂,其熔点明显低于单一组分的熔点。与传统离子液体相比,低共熔溶剂成本更低,制备更容易,可生物降解,具有100%原子利用率和生物相容性及无毒无害等绿色特性,这些优点使其在许多研究领域被广泛研究。本文介绍了低共熔溶剂的最新分类,综述了低共熔溶剂在电化学、气体吸收、有机合成、功能材料合成、萃取分离、药物增溶及生物质预处理中的应用,并对低共熔溶剂的未来发展进行了展望。     

低共熔溶剂催化有机合成反应的研究进展

低共熔溶剂(DESs)是一种新型的离子液体(ILs)类似物,与传统有机溶剂、离子液体相比,DESs具有低毒、廉价、易于合成、生物可降解性等特点,因此在众多领域广受关注。近年来DESs在有机合成领域备受关注,被广泛用作合成反应的溶剂、催化剂、反应物等,在有机反应方面存在很大发展空间,本文综述了DESs在有机合成反应中的应用,重点讨论其在氧化还原反应、取代反应、缩合反应、环化反应等方面的研究进展,为其开发应用提供新思路。     

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.     

低共熔溶剂在绿色有机合成中的应用

自1991年"绿色化学"的概念被提出以来,溶剂的绿色化一直备受关注.在过去的二十年时间里,离子液体得到长足发展,但是随着研究的不断深入,离子液体的部分弊端也慢慢浮现.在最近几年兴起了一种新型的低熔点混合物溶剂——低共熔溶剂.与传统离子液体相比,低共熔溶剂制备简单、价格便宜、均具有生物可降解性,因此被用来作为一种新型绿色溶剂.近年来,低共熔溶剂在绿色有机合成中的应用受到了越来越多的应用.本文重点从低共熔溶剂在环化反应、取代反应、加成反应、多组分反应以及酶催化反应等方面的应用讨论近几年来低共熔溶剂的研究进展,并对其发展趋势进行展望.     

离子液体中制备无机材料

离子液体作为潜在的“绿色”溶剂,具有许多传统溶剂无法比拟的优异性能,在有机合成、催化、液液分离和萃取等领域引起了广泛的研究。而在离子液体领域无机材料的制备是一个较新的发展分支,现已利用其合成出多种具有独特结构和性能的无机材料。本文就离子液体在无机材料制备方面的应用及发展趋势进行了综述。目前,对于制备无机材料,离子液体主要是作为电解液、表面活性剂或溶剂,本文介绍了其在应用中的优缺点,并指出该领域未来的发展趋势是离子热合成和集模板-溶剂-反应物于一身的离子液体反应。     

手性胍盐离子液体的合成

离子液体作溶剂、催化剂进行有机合成反应是近几年来各国化学家关注的热点之一[1].究其原因主要是离子液体具有低熔点、不挥发、不易燃易爆等特点,使其能代替传统有机合成与工业催化工程中的易挥发性溶剂(VOCs).再就是离子液体作为一种离子溶剂,可能存在1018种二元离子液体,而现在实际应用中的分子溶剂大概600种,离子液体的多样性使得在实际应用中可以通过调节离子液体的结构来调节离子液体的性质,从而为反应提供合适的溶剂环境,从而提高反应的产率、选择性以及立体选择性等[2].手性离子液体的合成和离子液体中的不对称催化一直都是离子液体研究的一个重要方面.Wasserscheid等[3,4]最近报道了从"手性池"(Chiral pool)衍生的新手性离子液体的合成和特性.最近我们报道一类简单的胍盐室温离子液体的合成及性质[5,6],新型胍盐离子液体由于其独特的性质得到了大家的关注[7-8].而手性胍盐离子液体还未见文献报道,因此我们从简单易得的手性胺出发合成了一系列的手性胍盐离子液体(Scheme 1),以新的手性胍盐离子液体作为不对称性催化反应新体系的工作正在进行.     

离子液体作为新型润滑材料的研究进展

离子液体的快速发展产生了许多具有应用价值的新型离子液体。目前,离子液体作为绿色溶剂已广泛应用于合成、催化和分离等许多领域用以替代传统有机溶剂。由于离子液体具有低熔点、低蒸气压、极性可调和安全稳定等诸多特性,可作为一种潜在的高效、通用型润滑剂,已经引起各国科学家的关注。本文从离子液体作为常规润滑剂、添加其他添加剂的离子液体作为润滑剂、离子液体作为常规润滑材料的添加剂以及离子液体在微纳机电系统中的润滑应用等4个方面综述了近几年离子液体在润滑摩擦方面的研究进展,分析和探讨了离子液体润滑剂在摩擦领域存在的问题,提出了离子液体润滑剂在摩擦领域的研究思路并展望了其应用前景。     

离子液体及其在分离分析中的应用进展

室温离子液体是一类熔点在室温附近的熔融盐，以其熔点低、蒸汽压小、电化学窗口宽、酸性可调节以及良好的溶解性等特点在电化学、有机合成、催化、分离等领域应用广泛。综述了离子液体在分离分析上的应用进展。参考文献48篇。     

原子转移自由基聚合法合成聚丙烯腈的研究进展

聚丙烯腈纤维是一种具有优良的化学和物理性能的高分子材料,高分子量、高等规度的聚丙烯腈(PAN)是合成高性能聚丙烯腈纤维的必要要求,原子转移自由基聚合法(ATRP)可以预先确定相对分子量且分散系数低,操作简单、反应条件温和,被广泛应用于聚丙烯腈的合成。本文介绍了原子转移自由基聚合的基本原理及其合成聚丙烯腈的研究概况,探讨了不同溶剂对聚合速率的影响、不同种类过渡金属催化剂及相关配体在聚合反应中的应用、引发剂的选择及分类。     

胆碱类低共熔溶剂的物性及应用

作为一种新型的离子液体,胆碱类低共熔溶剂具有相比于其他离子液体更为突出的特点,如低毒、生物可降解、价格低廉等,这些特点使得此类离子液体在绿色化学和工程化学中受到越来越多的关注。本文分析了胆碱类低共熔溶剂的凝固点、熔点、溶解度、黏度、表面张力、电导率等物性随温度、组成、水分等因素的变化及理论预测模型,并介绍了胆碱类低共熔溶剂在润滑、功能材料制备、电化学、有机合成及生物质催化转化等方面的潜在应用。最后就胆碱类低共熔溶剂研究及应用中存在的问题及难点对其前景做出展望。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.