微波辐射无溶剂条件下快速合成2,4,6-三芳基吡啶四氟硼酸盐

在微波辐射无溶剂条件下快速、高产率地合成了2,4,6-三芳基吡啶四氟硼酸盐化合物, 并对其进行核磁共振、红外光谱、元素分析表征. 同时得到了化合物4f的晶体, 对其进行了X单晶射线衍射表征. 结果表明, 该晶体属正交晶系, 空间群Pbca, a＝2.1050(2) nm, b＝1.64360(17) nm, c＝2.9209(3) nm, α＝β＝90.00°, γ＝90.00°, D_c＝1.276 g•cm^－3, V＝10.1057(17) nm^－3, Z＝16.     

2,4,6-三芳基吡啶的微波辐射促进合成

微波辐射;查尔酮;缩合反应;吡啶;叶立德     

低共熔溶剂及其应用研究进展

作为一类新型的绿色溶剂,低共熔溶剂具有蒸汽压低、无毒性、可生物降解、溶解性和导电性优良、电化学稳定窗口宽等独特的物理化学性质,并且可以通过选择合适的组成和配比来调节其性能,在很多领域中有着诱人的应用前景.本文从低共熔溶剂的组成、性质及其应用等3个方面综述了近年来低共熔溶剂的研究进展,并对目前研究中存在的问题进行了讨论.     

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。     

低共熔溶剂在高分子合成中的应用

低共熔溶剂(DES)是由两种或多种物质按一定比例混合而成的低熔点混合溶剂,其熔点显著低于每一个单纯组分的熔点,可被视为一种新的离子液体。与传统有机溶剂相比,DES具有来源广泛、成本低廉、易于制备、毒性低、生物可降解等优点,并已作为一种新型的绿色反应介质被广泛用于萃取分离、无机合成、有机合成和离子凝胶等领域。近年来,DES在高分子合成中的应用也吸引了广泛的研究兴趣。本综述从简述DES及其在有机合成中的应用出发,重点介绍它们用于缩合聚合、自由基聚合、阴离子聚合、电化学聚合、开环聚合和氧化聚合等高分子合成领域的研究进展,并对其发展趋势进行展望。     

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。     

低共熔溶剂的热稳定性研究

近年来,低共熔溶剂(DESs)引起了人们的广泛关注,在诸多领域得到应用。DESs一般由氢键供体(HBDs)和氢键受体(HBAs)通过氢键作用形成,其热稳定性研究对于其高温应用具有重要意义。本文利用热重分析法(TG)对40种DESs的热稳定性进行了系统研究,并得到了所研究DESs的开始分解温度(T_onset)。值得注意的是,DESs受热后的变化情况与离子液体不同,呈现出分阶段失重的现象。通常形成DESs的氢键在升温后首先被破坏,从而导致DESs分解成组成其的HBDs和HBAs。然后热稳定性较差(或者沸点较低)的HBDs首先分解(或挥发),而HBAs则在更高温度下分解(或挥发)。例如常见的HBA氯化胆碱(ChCl)在250 ℃附近开始分解。氢键强度对DESs受热后的表现起着重要的作用,DESs中的氢键会阻碍分子“逃脱”,使得T_onset向高温方向移动。此外,我们考察了阴离子、氢键供体、摩尔比对DESs热稳定性的影响,发现HBDs自身的挥发或分解对DESs的热稳定性起着决定性作用。由于用T_onset值会高估DESs的热稳定性,长期热稳定性的考察对其工业应用具有重要价值。本研究能帮助人们理解DESs的热分解行为,为制备具有适当热稳定性的DESs提供依据。     

镧在低共熔溶剂中的电沉积研究

以氯化胆碱/尿素低共熔溶剂为介质通过恒电位沉积法成功制备了形状和尺寸均一的橄榄状镧粒子. 采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线能量色散谱（EDX）和X射线光电子能谱（XPS）等技术对所制备的样品进行表征. 同时,研究了沉积电位、温度和时间等因素对样品尺寸、形貌的影响,确定恒电位法制备橄榄状镧粒子的优化工艺条件为沉积电位-1.7 V、温度80 ^oC和沉积时间15 min.     

微波促进下2-氨基-3-氰基-4-芳基-4H- 吡喃化合物的一锅法合成

标题化合物可在微波辐射下以良好的产率经一锅法合成，为2-氨基-4H-吡哺类化合物的制备提供了一种快速便捷的有效方法。     

EMIES/p-TsOH型低共熔溶剂的合成及其氧化脱硫性能的研究

通过1-乙基-3-甲基咪唑硫酸乙酯离子液体（EMIES）和对甲苯磺酸（p-TsOH）的混合物制备EMIES/p-TsOH型低共熔溶剂。其结构特征通过红外光谱、氢谱和热重技术进行了分析。并以EMIES/p-TsOH作为催化剂与萃取剂,H₂O₂作为氧化剂研究了其对模拟油中的硫化物的脱除性能。考察了反应温度、n（H₂O₂）/n（S）比、低共熔溶剂加入量及硫化物类型对脱硫效果的影响。在最佳的条件下,模拟油中二苯并噻吩（DBT）、4,6-二甲基二苯并噻吩（4,6-DMDBT）和苯并噻吩（BT）的脱除率分别为96.2%、92.2%和88.8%。经过五次循环使用后,DBT的脱除率仍达到93.6%。对该脱硫体系进行了动力学分析,其表观活化能为66.4kJ/mol。     

Green and highly efficient synthesis of pyranopyrazoles in choline chloride/urea deep eutectic solvent

A simple and efficient multicomponent protocol, using ammonium deep eutectic solvent as a dual catalyst and environmentally benign reaction medium, is developed for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives. This operationally simple protocol does not involve tedious workup or purification, affording the target compounds in short reaction times and excellent yields and avoiding the use of environmentally hazardous solvents and catalysts.     

Choline chloride based deep eutectic solvent as an efficient solvent for the benzylation of phenols

Deep eutectic solvents (such as the combination of urea and choline chloride) are found to be promising solvent and phase-transfer-media for benzylation of phenol. These methods avoided the complexity of multiple alkylations giving selectively O-alkylated aromatic products. Good to excellent yields of the corresponding benzyl phenyl ether were obtained. The non-toxic, biodegradable, inexpensive, and recyclable nature of DES make this protocol green and cost-effective.     

Choline chloride based eutectic solvent for the efficient synthesis of 2-amino-4H-chromen-4-yl phosphonate derivatives via multicomponent reaction under mild conditions

Synthesis of 2-amino-4H-chromen-4-ylphosphonate derivatives has been accomplished by the one-pot three-component reaction of salicylaldehyde, malononitrile/ethylcyanoacetate and dialkyl phosphites in the presence of reusable deep eutectic solvent (DES) under mild conditions. The advantages of this method are mild reaction conditions, simple work-up procedure, use of DES as a green solvent and an economical protocol for the preparation of important biologically active phosphorus-containing compounds.     

Metal-free and base-free decarboxylation of substituted cinnamic acids in a deep eutectic solvent

Abstract

A metal-free and base-free strategy was developed in DES to synthesize styrenes for the first time by decarboxylation of cinnamic acid derivatives, which provided a renewable and cost efficiently protocol to access various styrenes including those with functional groups such as 4-vinylphenol and 1-chloro-4-vinylbenzene.     

One-pot rapid synthesis of 4H-1-benzopyran derivatives in a deep eutectic solvent

A method for introducing a biologically active heterocycle, 2-methylquinoline into the 4-position of a 2-amino-4H-1-benzopyran skeleton is described. Choline chloride/glucose (1:1 molar ratio) was used as both the solvent and catalyst in the reaction of a salicylaldehyde, methylquinoline, and cyanoacetate to obtain 2-amino-4H-1-benzopyran derivatives in 48%–80% yields after short reaction times. The effects of the deep eutectic solvent type, substrate molar ratio, cosolvent, temperature, and reaction time were examined. The method has the advantages of simple steps, environmental friendliness, mild conditions, and wide substrate applicability. This is the first attempt to synthesize methylquinoline derivatives of 4H-1-benzopyran.     

Highly efficient and green esterification of carboxylic acids in deep eutectic solvents without any other additives

A protocol that carboxylic acids esterifies with the quaternary ammonium salt of deep eutectic solvent (DES) is presented, which opens a new access to ester using DES as alkylating agent, solvent, and catalyst. The reaction runs smoothly in DES without any other additives. Substituted cinnamic acids, aromatic acids, and aliphatic acids can be esterified in moderate to good yields. The advantages of this reaction include excellent functional group compatibility and simple reaction procedure.     

An atom-economic and odorless thia-Michael addition in a deep eutectic solvent

The first 100% atom-efficient and odorless protocol for carbon–sulfur bond formation in a deep eutectic solvent (DES) as both the reaction medium and catalyst is reported. The biodegradable and inexpensive DES provides an efficient and convenient ionic reaction medium for the thia-Michael addition with in situ generation of S-alkylisothiouronium salts in place of thiols without the urea by-product segment. This protocol offers several advantages including short reaction times, high yields, clean reactions, and inexpensive and commercially available starting materials.     

Chemoselective synthesis of xanthenes and tetraketones in a choline chloride-based deep eutectic solvent

A chemoselective synthesis of tetraketone and xanthene derivatives, by means of tandem Knoevenagel condensation and Michael addition in choline chloride-based deep eutectic solvents (DESs), is presented. The reaction of readily available aldehydes and active methylene compounds in malonic acid- and ZnCl₂-based DES gives various xanthenes derivatives with good to excellent yields under mild reaction conditions. On the other hand, tetraketones were synthesized in almost quantitative yields by simple condensation of an aldehyde and active methylene compounds in milder deep eutectic solvents of urea and SnCl₂. In addition, the reaction of other types of choline chloride-based DES leads to a mixture of tetraketone and xanthene.     

Solvent terminated natural deep eutectic solvent microextraction for concentration of curcuminoids in Curcumae Longae Rhizoma and turmeric tea

A novel solvent terminated microextraction method based on a natural deep eutectic solvent (L-menthol and lactic acid at a molar ratio of 1:2) coupled with high-performance liquid chromatography was proposed, which was utilized for the separation and enrichment of bisdemethoxycurcumin, demethoxycurcumin and curcumin in Curcumae Longae Rhizoma and turmeric tea. The effects of independent parameters on extraction efficiency were optimized by single-factor analysis. Subsequently, four predominated parameters affecting the extraction procedure, including extractant volume, salt concentration, demulsifier consumption, and demulsification time, were further evaluated by a central composite design. Under the optimized conditions, the linear ranges of calibration curves were 0.005–0.5 μg/mL for bisdemethoxycurcumin, 0.004–0.4 μg/mL for demethoxycurcumin, and 0.0045–0.45 μg/mL for curcumin, respectively. In addition, the developed method provided low detection limits (0.1–0.4 ng/mL) and high enrichment factors (279–350). Its intra-day and inter-day precision were carried out by relative standard deviation ranging from 2.2 to 9.2%. Finally, the applicability of this method was assessed by the analysis of Curcumae Longae Rhizoma and turmeric tea samples. The results showed that these samples were detected successfully and the spiked recoveries over the range of 85.3-108.9% with relative standard deviations of 1.6-8.9% were attained, indicating its high relative recoveries with good precision in real sample analysis.     

Magnetic graphene oxide modified with choline chloride-based deep eutectic solvent for the solid-phase extraction of protein

Four kinds of green deep eutectic solvents (DESs) based on choline chloride (ChCl) have been synthesized and coated on the surface of magnetic graphene oxide (Fe₃O₄@GO) to form Fe₃O₄@GO-DES for the magnetic solid-phase extraction of protein. X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and thermal gravimetric analysis (TGA) were employed to characterize Fe₃O₄@GO-DES, and the results indicated the successful preparation of Fe₃O₄@GO-DES. The UV–vis spectrophotometer was used to measure the concentration of protein after extraction. Single factor experiments proved that the extraction amount was influenced by the types of DESs, solution temperature, solution ionic strength, extraction time, protein concentration and the amount of Fe₃O₄@GO-DES. Comparison of Fe₃O₄@GO and Fe₃O₄@GO-DES was carried out by extracting bovine serum albumin, ovalbumin, bovine hemoglobin and lysozyme. The experimental results showed that the proposed Fe₃O₄@GO-DES performs better than Fe₃O₄@GO in the extraction of acidic protein. Desorption of protein was carried out by eluting the solid extractant with 0.005 mol L⁻¹ Na₂HPO₄ contained 1 mol L⁻¹ NaCl. The obtained elution efficiency was about 90.9%. Attributed to the convenient magnetic separation, the solid extractant could be easily recycled.