双核烷基咪唑过氧磷钨酸盐相转移催化剂合成及催化烯烃环氧化性能

合成并表征了一类双核长链烷基咪唑阳离子修饰的过氧磷钨杂多酸盐催化剂[Dnmin]1.5PW4O24,考察了催化剂在过氧化氢为氧源的烯烃环氧化反应中的催化活性.研究表明,这类催化剂在反应过程中表现出相转移催化现象,并具有较高的催化活性和选择性.其中,双核十二烷基咪唑杂多酸盐催化剂[D12min]1.5PW4O24的活性最佳,其环己烯转化率和环氧环己烷选择性分别达到97.7%和96.3%.催化剂在经过简单离心分离后可重复使用,重复使用4次后环己烯转化率和环氧环己烷选择性仍可分别达到72.4%和97.2%.催化剂[D12min]1.5PW4O24在其它几种烯烃的环氧化反应中均表现出相转移催化特性,且具有较高的催化活性.     

Synthesis and applications of quaternized highly branched polyacrylamide as a novel multi-site polymeric phase transfer catalyst

In current study, quaternized highly branched polyacrylamide (HBAA) was synthesized and used as an efficient multi-site polymeric phase transfer catalyst in nucleophilic substitution reactions and also in synthesis of α, β-unsaturated nitriles from reaction of acetonitrile and carbonyl compounds. The quaternized HBAA was synthesized via two steps. First, HBAA was synthesized via self-condensing vinyl polymerization of acrylamide at appropriate molar ratio of monomer to diperiodatocuprate(III). In the second step, 3-acrylamidopropyl trimethylammonium iodide was polymerized on peripheral area of the HBAA in the presence of diperiodatocuprate(III) solution again. The thermal behavior of HBAA and that of the quaternized HBAA were studied by DSC and TGA analysis. This phase transfer catalyst was easily recovered after reaction and reused several times without any loss of activity.     

Synthesis and catalytic activity of novel Ni-N complexes

A series of nickel complexes with 1,3-xylylenediamine, 1,2-diaminobenzene and 1,2-aminobenzylamine were first synthesized and characterized. The reaction of these amines with Ni(OAc)₂ · 4H₂O and NiCl₂ · 6H₂O in methanol or tetrahydrofuran resulted in the production of four novel nickel complexes I, II, III, and IV. The structure of each complex was determined by X-ray diffraction analysis. Each complex was also characterized using elemental analysis, ¹H NMR and IR. The complexes were then used to catalyze the Henry reaction, and good catalytic results (65?C99%) were achieved. The catalytic activity of the complexes was determined by ¹H NMR.     

Synthesis of 4-hydroxymethylbenzophenone by phase transfer catalytic method

An important organic intermediate 4-hydroxymethylbenzophenone was synthesized by halogenation and hydrolyzation with phase transfer catalytic method using 4-methylbenzophenone as raw material and the technological conditions of reactions were investigated as well. Experimental results show that N-bromosuccinimide (NBS) is a good reagent to give 4-bromomethylbenzophenone undergoing a radical reaction with 4-methylbenzophenone with the yield of about 70.7%; 4-bromomethylbenzophenone can be hydrolyzed under basic conditions in the presence of phase transfer catalyst triethylbenzylammonium chloride for 5 h to give 4-hydroxymethylbenzophenone with yield of 84.4%. After the crude product is recrystallized from tetrahydrofuran (THF), the final product is obtained with purity above 99%. The structure of the titled compound is determined by infrared spectrum(IR), proton nuclear magnetic resonance (HNMR), and mass spectrum (MS) and elemental analysis (EA). __________ Translated from Journal of central south university, 2005, 36(4) (in Chinese)     

Synthesis of a novel titanium complex catalyst and its catalytic performance for olefin polymerization

Russian Journal of Applied Chemistry - A phenoxy-ester Ti based complex of bis[5-methyl-3-trimethylsilyl phenyl salicylate]titanium(IV) dichloride was prepared for olefin polymerization. The...     

磷钨钒杂多酸相转移催化剂的制备及其深度氧化脱硫性能

以钒原子取代的Keggin型磷钨杂多酸与不同的季铵类阳离子表面活性剂反应合成了一系列磷钨钒杂多酸相转移催化剂,采用红外和X射线衍射对催化剂进行了表征。以H_2O_2为氧化剂,对模型柴油的氧化脱硫反应进行了研究,考察了季胺类表面活性剂种类、不同季胺盐含量、催化剂用量、氧硫比、反应温度等参数对反应的影响。结果表明,所制备的杂多酸相转移催化剂保留有杂多酸阴离子和季铵盐阳离子的结构特征。[(C_(16)H_(33)(CH_3)_3) N]_3H[PW_(11)VO_(40)]催化剂具有最佳的氧化脱硫性能和重复使用性能,在n(催化剂)/n(模型柴油)=1∶80,n(H_2O_2)/n(模型柴油)=8∶1,反应温度50℃,反应时间3 h的反应条件下,二苯并噻吩的转化率可达到100%;催化剂重复使用五次后,转化率为99.7%。反应过程中,该催化剂与反应物形成微乳体系,如同一个均相混合物,而反应结束体系静置一段时间后,催化剂和产物又形成两相,通过离心法就可以快速分离和回收催化剂。     

甘油作为相转移催化剂催化合成喹喔啉类化合物

本文以绿色介质水为溶剂,甘油作为相转移催化剂,通过1,2-二羰基化合物和1,2-二胺类化合物缩合合成一系列喹喔啉类化合物。甘油作为生物柴油工业的主要副产品,无毒无害,可生物降解,有机合成中的应用为其找到了很好的应用前景。     

相转移催化剂对催化柴油氧化脱硫作用的数学模型

经过顺序氧化反应动力学方程、相转移催化剂强化作用数学模型方程和萃取相平衡方程的推导,确定了催化柴油氧化萃取脱硫数学模型方程。研究表明,呈指数函数形式的相转移催化剂作用数学模型具有较高的计算精度。通过模型参数估值确定了氧化速率常数的频率因子和活化能、相平衡常数、相转移催化剂作用模型参数,建立了脱硫率数学模型。模型预测显示,柴油脱硫率随着氧化时间延长呈先提高后降低的趋势;氧化时间较短时,柴油脱硫率随相转移催化剂用量提高而增大,但氧化时间较长时的情况相反;柴油脱硫率随着氧化溶液体积分数增大或萃取剂与油比增大均呈提高的趋势。     

Synthesis of cyclic disulfides using didecyldimethylammonium bromide as phase transfer catalyst

A convenient, practical and general method for the synthesis of symmetrical and unsymmetrical cyclic disulfides based on the reaction of sulfur with sodium sulfide in the presence of didecyldimethylammonium bromide (DDAB) as a phase transfer catalyst is described.     

Synthesis and catalytic activity of a novel ionic liquid-functionalized metal–organic framework

In this research, a new heterogeneous catalyst is fabricated through covalent modification of iron-based metal–organic framework with ionic liquid. In more detail, using 2-aminoterephthalic acid and iron (III) chloride hexahydrate, amino-functionalized metal–organic framework has been synthesized and then reacted with 2,4,6-trichloro-1,3,5-triazine and 1,4-diazabicyclo[2.2.2]octane successively to furnish ionic liquid on metal–organic framework. The as-prepared catalyst was characterized by FTIR, TGA, BET, SEM/EDS, XRD and elemental mapping analysis and then employed for catalyzing synthesis of pyrano [2,3‐d]pyrimidines (with yields of 80–100%) from one-pot three-component reaction of aldehydes, barbituric acid and malononitrile in aqueous media. The catalytic test inferred high catalytic activity of the catalyst, superior to that of IL and metal–organic framework. Furthermore, the catalyst could be recovered and recycled for five reaction runs with preserving its morphology.

Graphic abstract

     

Synthesis of dialkoxydiphenylmethane under phase transfer catalytic condition assisted by ultrasonic irradiation

The synthesis of dialkoxyldiphenylmethanes (DAODPMs) from the reactions of alcohols and dichlorodiphenylmethane (DCDPM) were successfully carried out in a liquid-liquid phase transfer catalytic reaction (LL-PTC). The reactions are greatly enhanced by irradiation with ultrasonic waves. Two sequential reactions in the organic-phase solution proceed to produce the desired product. Only the di-chloro-substituted product dialkoxyldiphenylmethanes (DAODPM) is obtained, indicating that the second reaction is faster than the first one in the organic phase. Explanations for the phenomena of the experimental results are provided.     

Kinetic study of dichlorocyclopropanation of 4-vinyl-1-cyclohexene by a novel multisite phase transfer catalyst

In this work, the dichlorocyclopropanation of 4-vinyl-1-cyclohexene catalyzed by a new novel phase transfer catalyst was carried out in an alkaline solution/chloroform two-phase medium. This new synthesized phase transfer catalyst, 1,4-bis(triethylmethylammonium)benzene dichloride (DC-X), which possesses two-site activity, was obtained from the reaction of ,′-dichloro-p-xylene and triethylamine. This new novel phase transfer catalyst exhibits higher reactivity than those of the other quaternary ammonium salts. The reaction of chloroform and alkali was carried out at the interface to generate dichlorocarbene which can further react with 4-vinyl-1-cyclohexene to produce mono-dichlorocyclopropane and bis-dichlorocyclopropane products. Rational mechanism of the dichlorocyclopropanation is proposed according to the experimental evidence. The reaction follows a pseudo-first-order rate law. Kinetics of the reactions such as: effect of the catalysts, agitation speed, temperature, alkaline concentration, amount of DC-X catalyst, amount of 4-vinyl-1-cyclohexene (reactant) and volume of chloroform (organic solvent) on the reaction rate were investigated in detail. Peculiar phenomenon for the dependence of the reaction rate on the amount of DC-X catalyst is explained satisfactorily.     

基于γ-环糊精的谷胱甘肽过氧化物酶模拟物的构建及催化作用

基于对天然谷胱甘肽过氧化物酶(GPX)结构与功能的理解,我们利用超分子化学的方法和原理,选择γ-环糊精为骨架,通过引入催化基团硒或碲,设计并合成了7种基于γ-环糊精的新型谷胱甘肽过氧化物酶(GPX)模拟物,并采用元素分析、红外光谱、核磁共振等手段对其结构进行了详细的表征和确认。运用GPX经典双酶体系法测定了它们的GPX活性,实验结果表明:6,6’双碲桥联γ-环糊精(6-diTe-γ-CD)表现出了最高的GPX活性,其催化GSH还原过氧化氢(H2O2)、叔丁基过氧化氢(t-BuOOH)和枯烯过氧化氢(CuOOH)的活力分别是传统小分子硒酶Ebselen的147.3、1897.9和663.9倍,该结果是目前报道的环糊精GPX模拟物中酶活力最高的。     

Synthesis and catalytic activity of novel xylyl‐linked benzimidazolium salts

The reaction of 1‐alkylbenzimidazole derivatives with o‐/p‐di(chloromethyl)benzene results in the formation of the new o‐/p‐xylyl‐linked bis(benzimidazolium) salts, 1 and 2, respectively. The salts were characterized by NMR spectroscopy and elemental analysis. The in situ prepared complexes derived from Pd(OAc)₂–1 and 2 exhibit catalytic activity (61–98%), to give the Heck coupling products of aryl bromides and styrene. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of plasmochemical treatment of platinum catalyst on dispersity of metal phase and its catalytic activity

We studied how treatment of 0.64 wt % Pt/SiO₂ catalyst with a glow-discharge plasma in O₂ and a high-frequency plasma in H₂ (HF H₂) influences the cyclohexane dehydrogenation reaction. The effect of plasmochemical treatment on the average diameter of platinum particles was established by the method of X-ray diffraction analysis. It was found that oxygen plasma increases the surface area of the metal by ∼15% and diminishes activity by raising the activation energy and reducing the number of active centers per unit surface of the metal. The HF H₂ plasma increases the reaction rate constant many times over, due to the number of active centers per unit surface of the metal rising sharply while the size of the Pt particles remains unchanged.     

单相Co_2C的制备及其费-托合成催化性能研究

采用CO与金属钴在温度280℃,压力2 MPa的条件下反应48 h后制备得到单相Co_2C催化剂。通过XRD、H2-TPR、TEM和XAS对催化剂的结构和组成进行表征并考察了单相Co_2C催化剂在费-托合成反应中的稳定性与催化性能。结果表明,随着费-托合成反应的进行,Co_2C催化剂的活性缓慢上升,同时伴随着产物中甲烷的选择性逐渐降低,C5+的选择性逐渐升高。对比反应前后催化剂发现,反应后的催化剂为Co_2C和少量金属Co的混合相,表明在费-托合成反应条件下,单相Co_2C会发生部分分解,生成的金属Co会导致CO的转化率和产物的选择性发生变化。     

Activity and behavior of imidazolium salts as a phase transfer catalyst for a liquid-liquid phase system

The structure-activity relationship and behavior of N,N′-dialkylimidazolium salts as a phase transfer and/or ion-exchange catalyst in a liquid-liquid phase system were investigated for the reactions such as β-elimination reaction of alkyl halides, nucleophilic epoxidation of α,β-unsaturated carbonyl compounds, alkylation of active methylenes, and nucleophilic substitution reaction.