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.     

离子液体中13-芳基-5,7,12,14-四氢二苯并[b, i]氧杂蒽5,7,12,14(13H)-四酮衍生物的绿色高效合成

在离子液体[bmim+][BF4-]中高产率的合成了一系列13-芳基-5,7,12,14-四氢二苯并[b, i]氧杂蒽-5,7,12,14(13H)-四酮类化合物。该反应操作步骤简单,离子液体易于与产物分离,并且离子液体可以循环使用。     

离子液体中2,4,6-三溴苯酚的电化学还原脱卤

<正>室温离子液体的许多独特的性质为其在化学分离、电化学传感器、电池等领域展示了广阔的应用前景[1-3]。室温离子液体作为有机反应介质,可以克服水溶液电化学窗口较窄的缺点,还可避免或减少造成二次污染的大量有机溶剂[4]。利用离子液体的导电性,可将电化学反应中的     

[Bmim]FeCl_4离子液体的物理性质

研究了自制[Bmim]FeCl4离子液体的电导率、黏度与温度的关系,并与文献数据进行了对比.结果表明,采用落球法和旋转法都能准确地测量[Bmim]FeCl4离子液体的黏度;与Andrade方程相比,VTF方程能更好地拟合[Bmim]FeCl4离子液体的黏度和温度的关系,其相关系数达0.999 9.采用不同电导率仪测量的[Bmim]FeCl4离子液体的电导率有较大差别;相比Arrhenius方程而言,VTF方程能更好地拟合电导率与温度的关系;随着温度的变化,电导率与黏度的关系符合Walden规则,其相关系数达到0.99以上.     

绿色离子液体中纳米钯催化剂的制备及其催化Heck-Mizoroki反应性能

发展了在非卤素绿色离子液体1-丁基-3-甲基咪唑离子液体乳酸盐中制备纳米Pd催化剂的简便化学方法.透射电镜结果表明,Pd纳米粒子高度分散在[Bmim]Lac离子液体中,平均粒径为2.2–3.1 nm.Pd纳米粒子的大小随着体系中[Bmim]Lac与Pd(OAc)2摩尔比减小和温度升高而增大.考察了离子液体稳定纳米Pd催化剂(PdNPs@[Bmim]Lac)催化Heck-Mizoroki反应性能,并对反应条件进行了优化.结果表明,所制备的离子液体稳定的纳米Pd催化剂在优化条件下可高效催化系列卤代芳烃与烯烃的Heck-Mizoroki反应,且可循环使用6次.     

辣根过氧化物酶在亲水性离子液体中的活性与稳定性研究

基于辣根过氧化物酶对过氧化氢氧化愈创木酚这个显色反应的催化作用,研究了辣根过氧化物酶在七种亲水性离子液体[C2mim][BF4]、[C4mim][BF4]、[C6mim][BF4]、[C4mim]HSO4、[C4mim]Cl、[C4mim]NO3、[C4mim][CF3CO2]中的活性与稳定性变化.结果表明辣根过氧化物酶在不同离子液体中均有不同程度的失活,辣根过氧化物酶活性随离子液体极性增强而降低.辣根过氧化物酶在含[C4mim]Cl离子液体的介质中,随着温度升高,[C4mim]Cl对辣根过氧化物酶的失活过程起加速作用,离子液体浓度越高,酶的热稳定性越差.紫外-可见光谱研究表明,在含[Cnmim][BF4]、[C4mim]HSO4、[C4mim]Cl、[C4mim]NO3的介质中,辣根过氧化物酶血红素中心最大吸收峰没有发生变化,但吸收值增强,证明离子液体使酶的血红素基团暴露于介质中而增强了吸收;而在含[C4mim][CF3CO2]的介质中,辣根过氧化物酶血红素基团最大吸收峰区发生蓝移,证明有部分血红素基团被离子液体破坏而脱落.     

Brønsted酸性离子液体中的二甘醇脱水环化反应

首次报道了Brønsted酸性离子液体介质中的二甘醇的脱水环化反应,考察了不同的离子液体、离子液体/二甘醇摩尔比、反应温度和时间对反应的影响。结果表明,Brønsted酸性离子液体作为反应介质能够促进脱水环化反应的有效进行,且在离子液体1-(3-磺酸根丙基)-3-甲基咪唑硫酸氢盐([SPmim]HSO4)中,二甘醇的转化率和1,4-二氧六环的选择性更高。采用Hammett指示剂法测定了离子液体的酸度函数H0,其酸性强弱顺序为[SPmim]HSO4 > [Bmim]HSO4 > [Amim]HSO4 > [Hmim]BF4> [Bmim]H2PO4 >[Amim]H2PO4 > [Hmim]Tsa,这与离子液体在脱水环化反应中的催化效果一致。当温度为170 ˚C,离子液体/二甘醇摩尔比为1:1时,二甘醇在[SPmim]HSO4中反应2 h,转化率可达到97.0%,1,4-二氧六环的选择性为89.3%。     

离子液体[bmim]Cl-CrCl2促进的Reformatsky反应研究

用无水氯化铬(CrCl2)和氯化1-丁基-3-甲基咪唑([bmim]Cl)制备了离子液体[bmim]Cl-CrCl2, 考察了CrCl2与[bmim]Cl物质的量比以及离子液体与底物物质的量比对Reformatsky反应的影响, 研究了[bmim]Cl-CrCl2促进不同底物发生的Reformatsky反应. 结果表明, 离子液体[bmim]Cl-CrCl2不仅能促进醛、酮与α-溴代酸酯的反应, 以极好的产率得到β-羟基酸酯; 而且能较好地诱导α-溴代苯乙酮与醛、酮的反应, 以较高的产率得到β-羟基酮. 该离子液体经处理后可以重复使用, 是一种Reformatsky反应的绿色化学方法.     

咪唑类离子液体中合成β-烯胺酮的研究

本文通过修饰阴阳离子合成了一系列咪唑型离子液体,以β-烯胺酮的合成为反应探针,考察离子液体结构和活性之间的关系。结果表明:阴阳离子对离子液体的活性都有显著的影响。阴离子为BF4-时,阳离子活性顺序为[Hmim]+[bmim]+,[emim]+[bmmim]+,其中[Hmim]BF4作反应介质,反应时间为10min,产率可达96%。当阳离子为[Hmim]+时,阴离子BF4-,Tsa-,Br-和NO3-活性均较高,产率达到93%以上,但阴离子HSO4-显著降低离子液体的活性,反应30min,产物收率仅有60%;阳离子为[bmim]+时,[bmim]Br[bmim]PF6[bmim]BF4,产率达到85%以上;而阴离子为HSO4-和H2PO4-时,离子液体活性变差,收率低于70%。离子液体[Hmim]BF4重复使用5次,β-烯胺酮产率基本不变,反应10min后,仍达89%。     

H_3PW_(12)O_(40)在离子液体中催化β-萘甲醚乙酰化反应

利用吡啶和正溴丁烷合成离子液体中间体[BPy]Br,再由[BPy]Br和NaBF4合成了离子液体[BPy]BF4,对其进行了FT-IR,1 H NMR和TG-DTA表征.将合成的离子液体作为溶剂,磷钨酸为催化剂,催化β-萘甲醚(MM)和乙酸酐(AA)的乙酰化反应.结果表明,该反应的主要产物是2-甲氧基-1-萘乙酮.反应的较佳工艺条件为:β-萘甲醚0.01mol,β-萘甲醚与乙酸酐的摩尔比为1∶1.5,磷钨酸0.05g,100℃下反应4h,反应物β-萘甲醚的转化率达到57.04%,最高选择性可达99.04%.通过萃取分离实现回收磷钨酸-离子液体的催化体系,并可循环使用5次,催化活性无下降.     

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%.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.