Liquid-phase synthesis of polyhydroquinoline using task-specific ionic liquid technology

A new strategy for the synthesis of polyhydroquinolines from task-specific ionic liquids (TSIL) as a soluble support was developed. The preparation of the polyhydroquinolines by a three-component reaction was achieved by using ionic liquid-phase bound beta-oxo esters. These starting functionalized esters were synthesized by a solventless transesterification without catalyst under microwave irradiation. The structure of the intermediates in each step was verified routinely by spectroscopic analysis, and after oxidation of the polyhydroquinolines grafted on the TSIL with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or after cleavage (transesterification, saponification-acidification), the target compounds were obtained in good yields and high purities.     

Ionic liquid incorporated polystyrene resin for solid-phase peptide synthesis

Ionic liquid (IL) resins with an ionic liquid environment on solid support were prepared by immobilizing ionic liquid spacers on polystyrene (PS) resin. The properties of IL resins were dramatically changed as the anions of IL were exchanged. The performance of IL resins for solid-phase peptide synthesis (SPPS) was evaluated by measuring coupling kinetics of the first amino acid and synthesizing several peptides on IL resins.     

Bicyclic imidazolium-based ionic liquids: synthesis and characterization

We previously reported the use of imidazole as starting compound for preparing a bicyclic imidazolium ionic liquid, [b-3C-im][NTf₂], with an overall 29% isolated yield in four synthetic steps. This new room temperature ionic liquid was shown to be far more chemically stable than commonly used [bmim][PF₆], [bdmim][PF₆], and [bdmim][NTf₂]. Because of this intriguing chemical stability, it prompted us to develop a more generalized and high yielding synthesis so that molecular diversity of bicyclic ionic liquids may be explored. In this work, we amended the previous synthetic route by employing 4-chlorobutyronitrile or 5-chlorovaleronitrile as starting materials and successfully developed a five-step synthesis of a series of novel bicyclic imidazolium-based ionic liquids in 40-53% overall isolated yields. We investigated intrinsic reactivity of all bicyclic ionic liquids prepared and found that, under strongly basic conditions, among all tested ionic liquids the 5,5-membered [R-3C-im][NTf₂] ionic liquids were most stable to solvent deuterium isotope exchange while the previously reported [bdmim][NTf₂] ionic liquid was 50% deuterium exchanged at its C-2 methyl in 30 min at ambient temperature. Under identical condition, the commonly used [bmim][NTf₂] ionic liquid was deuterium exchanged instantaneously at its C-2 hydrogen. In the absence of bases, only [bmim][PF₆] was deuterium exchanged (50% within 1 h) and all other ionic liquids gave no detectable exchanges even after 25 days at ambient temperature. Moreover, both [bmim][NTf₂] and [bdmim][NTf₂] ionic liquids were readily methylated at C-2 position with methyl iodide under basic condition at room temperature. Under the same condition, [R-3C-im][NTf₂] and [R-4C-im][NTf₂] ionic liquids were completely stable and chemically inert. We envisioned that [R-3C-im][NTf₂] should be well suited as solvents for organic synthesis.     

Bicyclic 1,2,3-triazolium ionic liquids: synthesis, characterization, and application to rutaecarpine synthesis

Starting with commercial reagents, bicyclic 1,2,3-triazolium ionic liquids [b-3C-tr][NTf(2)] (1) and [b-4C-tr][NTf(2)] (2) were synthesized in four steps with high overall isolated yields of 68% and 76%, respectively. Since the C-5 hydrogen is acidic, under basic condition ionic liquids 1 and 2 were readily methylated with methyl iodide to afford chemically stable ionic liquids 7 and 8 at room temperature (88% and 82%, respectively). Ionic liquid 1 was used as the ionic solvent to demonstrate its usefulness for the synthesis of rutaecarpine, a natural product.     

尿素醇解合成碳酸二甲酯过程中离子液体催化剂的含量分析

提出了尿素醇解合成碳酸二甲酯体系中1-甲基-3-丁基咪唑氯化锌离子液体催化剂的含量分析方法。采用紫外光谱法测定了离子液体催化剂的最大吸收波长,并建立了标准工作曲线,其线性相关系数为0.9986,方法的相对标准偏差RSD为2.5%,回收率为98.7%～102.4%。     

Efficient combination of task-specific ionic liquid and microwave dielectric heating applied to one-pot three component synthesis of a small library of 4-thiazolidinones

The first report of the use of task-specific ionic liquid as synthetic equivalent of ionic liquid-phase matrice for the preparation of a small library of 4-thiazolidinones is reported in this paper. The starting (ethyleneglycol)ionic liquid-phase is functionalized in good yields with 4-(formylphenoxy)butyric acid by using usual esterification reaction conditions (DCC/DMAP as catalyst). The synthesis of the ionic liquid-phase bound 4-thiazolidinones was performed by a one-pot three-component condensation under microwave dielectric heating. The final cleavage under microwave/catalysis strategy provides the expected 4-thiazolidinones in high purity after flash-chromatography purification. According to the ionic liquid-phase organic synthesis (IoLiPOS) methodology, it was found that optimized reaction conditions were performed by standard analytical methods (NMR, TLC). The ¹H, ¹³C NMR spectrum of some representative 4-thiazolidinones and ionic liquid-phase bound benzaldehyde are also reported.     

离子热法合成沸石咪唑骨架材料及其溶解-结晶机理研究

基于沸石咪唑骨架材料在离子液体和低共熔溶剂中冷却结晶的析出方式,开发了一种离子热法合成沸石咪唑骨架材料的新途径,采用X射线衍射、扫描电镜、核磁共振光谱、红外光谱以及热重分析等方法对制备的产物进行了表征,研究了合成条件对产物结晶度、尺寸和形貌的影响,探讨了沸石咪唑骨架材料在离子热合成体系中的溶解-结晶析出机理.研究发现,冷却速率能够影响产物形貌,急速冷却时,sod(RCSR代码)型产物的形貌为球形,zni(RCSR代码)型产物为棒状或平板状;程序控制冷却时,sod型产物的形貌为多面体,zni型产物呈团簇状.     

A novel one step synthesis of silver nanoparticles using room temperature ionic liquid and their biocidal activity

This article reports the synthesis of silver Nan particles (SNPs) using 1-(dodecyl) 2 amino-pyridinium bromide ionic liquid. This is a new one phase method for the synthesis of uniform monodispersed crystalline silver nanoparticles in a water-ionic liquid system. In this work, the functionalized room temperature IL acts as stabilizing agent and solvent. Hydrazine hydrate acts as reducing agent. To the best of our knowledge, there is no report of the synthesis of metal nanoparticles using this ionic liquid. The synthesis of silver nanoparticles is very primarily studied by UV-Visible spectroscopic analysis. The TEM and particle size distribution was used to study morphology and size of the particles. The charge on synthesized SNPs was determined by Zeta potential. The silver nanoparticles have been known to have inhibitory and bactericidal effect. The investigation of antibacterial activities of ionic liquid stabilized silver nanoparticles was performed by measurement of the minimum inhibitory concentration.     

吗啡啉碱性离子液体催化合成油酸甲酯

采用两步法合成了由阳离子N-甲基-N-丁基吗啡啉和阴离子氢氧根搭配的[Nbmm]OH新型碱性离子液体。实验利用FT-IR、元素分析和TGA分别对该离子液体的化学结构和热稳定性进行了表征。结果表明,该离子液体的热稳定性超过200℃。对该离子液体的溶解性能进行了考察, 结果表明,该离子液体能与强极性溶剂互溶,而且其水溶液的碱性较强。为了考察该离子液体对酯化反应的催化活性,实验过程中以油酸和甲醇反应生成油酸甲酯的酯化反应为模型反应,评价该离子液体的催化活性。结果表明,当反应温度60℃、酸醇比为1:6、离子液体加入量为原料总质量的15%、反应10 h时,油酸转化率达93.9%,而且该离子液体易于从反应体系中分离,可以循环使用。     

Solvothermal aluminophosphate zeotype synthesis with ionic liquid precursors

We have carried out a study of aluminophosphate framework synthesis using several amine based ionic liquids and their parent amines as solvent and template. The results suggest that in the presence of fluoride ions from hydrofluoric acid the ionic liquids and their parent amines produce the same frameworks, while in synthesis without fluoride ions the products are not related. The results include the synthesis and crystal structure of a novel extra-large pore material using 1-methylpyrrolidine as solvent and template. The relationship between this and sodalite, which can be synthesised in cobalt aluminophosphate form using an ionic liquid prepared from 1-methylpyrrolidine is described. The crystal structures of two other new layered materials are also presented.     

Amino-functionalized ionic liquid as a nucleophilic scavenger in solution phase combinatorial synthesis

A new functionalized ionic liquid, 1-aminoethyl-3-methylimidazolium hexafluorophosphate was synthesized from 1-methylimidazole and 2-bromoethylamine hydrobromide. This ionic liquid was found to be an efficient scavenger for removing excess electrophiles, such as benzoyl chloride, p-toluenesulfochloride, phenyl isothiocyanate, and p-chlorophenyl isocyanate, in a solution-phase parallel synthesis. The resulting ionic liquid derivatives can be separated directly from the reaction mixture. Desired products were obtained with high purity. Only 1.5-2.0 equiv of this scavenger was needed with a sequestration time of less than 35 min. In addition, the used ionic liquid can be regenerated and recycled several times without significant loss of activity.     

Ionic liquid phase technology supported the three component synthesis of Hantzsch 1,4-dihydropyridines and Biginelli 3,4-dihydropyrimidin-2(1H)-ones under microwave dielectric heating

A microwave dielectric heating assisted liquid phase synthesis of 1,4-dihydropyridines, 3,4-dihydropyrimidin-2(1H)-ones, pyridines and polyhydroquinolines using task-specific ionic liquid as a soluble support was described. The efficiency of the ionic liquid phase organic synthesis (IoLiPOS) methodology was demonstrated by using a one-pot three component condensation. The structure of the intermediates in each step was verified routinely by spectroscopic analysis and, after cleavage the target compounds were obtained in good yields and high purities.     

Ionothermal synthesis of polyoxometalates

An emerging approach: In the ionothermal synthesis of transition-metal-oxide clusters an ionic liquid acts as a solvent, structure-directing agent, and charge-compensating species. The method may open new convenient routes for the synthesis of polyoxometalate-based materials.     

Development in the green synthesis of cyclic carbonate from carbon dioxide using ionic liquids

This brief review presents the recent development in the synthesis of cyclic carbonate from carbon dioxide (CO₂) using ionic liquids as catalyst and/or reaction medium. The synthesis of cyclic carbonate includes three aspects: catalytic reaction of CO₂ and epoxide, electrochemical reaction of CO₂ and epoxide, and oxidative carboxylation of olefin. Some ionic liquids are suitable catalysts and/or solvents to the CO₂ fixation to produce cyclic carbonate. The activity of ionic liquid is greatly enhanced by the addition of Lewis acidic compounds of metal halides or metal complexes that have no or low activity by themselves. Using ionic liquids for the electrochemical synthesis of the cyclic carbonate can avoid harmful organic solvents, supporting electrolytes and catalysts, which are necessary for conventional electrochemical reaction systems. Although the ionic liquid is better for the oxidative carboxylation of olefin than the ordinary catalysts reported previously, this reaction system is at a preliminary stage. Using the ionic liquids, the synthesis process will become greener and simpler because of easy product separation and catalyst recycling and unnecessary use of volatile and harmful organic solvents.     

Novel biodegradable protonic ionic liquid for the Fischer indole synthesis reaction

Novel eco-friendly tetramethylguanidinium propanesulfonic acid trifluoromethylacetate ([TMGHPS][TFA]) ionic liquid was developed as catalyst and medium for the Fischer indole synthesis of a wide variety of hydrazines and ketones. The indole products were isolated in high yields and with minimal amounts of organic solvent. This reaction showed that [TMGHPS][TFA] can be regenerated and reused with reproducible yields without eroding the integrity of the ionic liquid.     

A green approach for efficient synthesis of N-substituted pyrroles in ionic liquid under microwave irradiation

A rapid synthesis of N-substituted pyrroles has been described by the reaction of 4-hydroxyproline with isatins in ionic liquid under microwave irradiation. The recovered ionic liquid was reused for six cycles. The reaction proceeds without the addition of any acid promoter     

Recent trends in the synthesis of polyelectrolytes

Recent developments in the synthesis of polyelectrolytes are highlighted, with respect to the nature of the ionic groups, the polymer backbones, synthetic methods, and additional functionality given to the polyelectrolytes. In fact, the synthesis of new polyelectrolytes is mostly driven by material aspects, currently. The article pays particular attention to strong polyelectrolytes, and the new methods of controlled polymerization. These methods and the so-called click reactions have enabled novel designs of polyelectrolytes. Nevertheless, the polymerization of unprotected ionic monomers is still challenging and limits the synthetic possibilities. The structural aspects are complemented by considerations with respect to the aspired uses of the new polyelectrolytes.     

Electrochemical synthesis of gallium nanowires and macroporous structures in an ionic liquid

The electrochemical synthesis of gallium nanostructures in an ionic liquid is presented. Gallium nanowires and macroporous structures were synthesized by the template-assisted electrodeposition in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py(1,4)]TFSA) containing GaCl(3) as the precursor. Track-etched polycarbonate membranes with an average pore diameter of 90 nm and a thickness of 21 μm were used as templates for the nanowire synthesis. Ga nanowires with a length of more than 4 μm and an average diameter corresponding to that of the template's pores were easily obtained by this method. Macroporous structures with an average pore diameter of 600 nm were obtained by the electrochemical deposition of Ga inside polystyrene colloidal crystal templates and the subsequent removal of the template by THF. The macroporous deposit showed a granular morphology with smallest grain sizes of about 40 nm and light reflections. The nanostructures of Ga were characterized by HR-SEM and EDX analysis.     

One-pot synthesis of quinoxaline-2-carboxylate derivatives using ionic liquid as reusable reaction media

The catalyst-free one-pot synthesis of quinoxaline-2-carboxylate is reported by the reaction of α-halo-β-ketoesters with 1,2-diamines using an ionic liquid as an environmentally benign solvent. The recovered ionic liquid was reused for four to five cycles. Moreover, the method is applicable for a variety of 1,2-diamines and α-halo-β-ketoesters.     

Ionic liquid mediated CO2 activation for DMC synthesis

Promoted catalytic reaction between methanol and CO2 for dimethyl carbonate(DMC) synthesis is conducted over K2CO3/CH3 I catalyst in the presence of ionic liquid under microwave irradiation.The effect of ionic liquids incorporated with microwave irradiation on the yield of DMC is investigated.DMC was found to form at lower temperature in a relative short time,which indicated an enhanced catalytic process by ionic liquid.Among the ionic liquids used,1-butyl-3-methylimidazolium chloride is the most effective promoter.Density functional theory calculations indicate that CO2 bond lengths and angles changed due to the molecular interaction of ionic liquid and CO2,resulting in the activation of CO2 molecules and consequently the acceleration of reaction rate.