杂多酸催化剂研究进展

1杂多酸概述杂多酸（Heteropolyacid）,也称多金属氧簇（Polyoxometalate）,是一类由氧原子桥接金属原子形成的金属-氧簇化合物.杂多酸具有良好的催化性能,是高效的双功能催化剂,即有酸催化性能,又具有氧化还原催化性能.杂多酸结构稳定,可以用在均相或者非均相催化环境,     

Cellulose sulfuric acid as a bio-supported and recyclable solid acid catalyst for the one-pot synthesis of 2,4,5-triarylimidazoles under microwave irradiation

Abstract

A simple, rapid, and highly efficient method has been attempted for the three-component condensation of benzil/benzoin, aldehydes, and ammonium acetate under microwave irradiation in the presence of a catalytic amount of bio-supported cellulose sulfuric acid under solvent-free conditions to afford the 2,4,5-triarylimidazole derivatives. The catalyst is easily prepared, inexpensive, separated simply by filtration, gives excellent yield of products with shorter reaction times, and is recyclable several times.     

微波辐射催化合成肉桂酸苄酯

肉桂酸苄酯是一种具有弱苏合香、花香等香气的香料,主要用于配制龙蜒香,在东方型香脂中作为定香剂,也可用作皂用、化妆用及果实香精的调香配料。肉桂酸苄酯的合成,在工业上,主要采用肉桂酸钠与氯化苄在二乙胺作用下反应,反应时间长达17h,产率80％以上。近年来的研究     

Silica sulfuric acid-catalyzed expeditious environment-friendly hydrolysis of carboxylic acid esters under microwave irradiation

Silica sulfuric acid was found to be an efficient, recoverable, reusable and environment-friendly catalyst for the fast hydrolysis of various carboxylic acid esters in high conversions and selectivities under microwave irradiation conditions. This protocol has the advantages of no corrosion, no environmental pollution, high reaction rate, high yield, and simple work-up procedure.     

微波辐射下的芳基甲酰氨基硫脲的合成

本文报道了以水为介质, 在微波辐射下的芳基甲酰氨基硫脲的合成。该法反应快, 产率高。     

Solvent-free,scalable and expeditious synthesis of benzanilides under microwave irradiation using clay doped with palladium nanoparticles as a recyclable and efficient catalyst

Benzanilide synthesis through amide bond formation was effectively carried out by palladium-doped clay catalyst using microwave irradiation under solvent-free conditions. Products were obtained with excellent yield in very short reaction time and only a small amount of the catalyst was used. The catalyst could be separated easily and recycled several times with insignificant loss in catalytic activity. No column purification was required and the products were purified by the crystallization method. The heterogeneous character of the catalyst in a ligand-free, solvent-free and base-free system supports for a practical and environmentally benign process.     

单手性臂脱氧胆酸分子钳的设计与微波合成

分子钳人工受体的研究已成为生物有机化学和超分子化学前沿领域的研究热点.钳型结构受体以其灵活的结构及易于将裂穴内功能团汇聚在受体与底物结合的活性部位上等特点,对于实现主客体形状、大小和功能互补特别有效.     

Deprotection of oximes using urea nitrate under microwave irradiation

A new mild and efficient method for the cleavage of oximes to carbonyl compounds using readily available urea nitrate in acetonitrile-water (95:5), under microwave irradiation within 2 min, in good yields is reported     

微波辐射下有效合成缩氨基硫脲类化合物

将肼基二硫代甲酸甲酯与相应的醛或酮在微波辐射下,经2~3.5m in反应得到化合物3-二取代甲(乙)撑肼基二硫代甲酸甲酯1,收率90~96%,然后将化合物1与胺在微波辐射下,经35~45m in反应得到目标化合物2~4,收率68~90%。微波辐射法比常规法显著的缩短了反应时间,提高了收率。共计合成目标化合物19个。以上化合物均经过熔点测定、质谱、红外光谱、核磁共振氢谱对其结构进行确证。     

无溶剂微波照射下2－取代苯并咪唑的合成

用PPA作催化剂，在无溶剂微波照射下合成了10种2－取代苯并咪唑，为该类化 合物的合成提供了一种新方法。与常规方法相比，反应时间大大缩短，产率与传统 合成方法相当。     

微波合成水杨酸异丙酯

研究了微波合成水杨酸异丙酯的工艺，与常规方法相对比，发现利用微波合成 水杨酸异丙酯具有反应速度快、转化率高、杂质含量小、后处理简单、无三废排放 等优点。     

Facile construction of symmetric biaryls using (BeDABCO)2Pd2Cl6 as an efficient and highly active catalyst under microwave irradiation

An efficient catalytic system using (BeDABCO)₂Pd₂Cl₆ (BeDABCO, benzyl‐1,4‐diazabicyclo[2.2.2]octane) was developed for the homo‐coupling reaction of various aryl halides. Due to the combination of ionic homogeneous metal catalyst and microwave irradiation, symmetric biaryls were produced in excellent yields and short reaction times in N‐methyl‐2‐pyrrolidone at 120 °C. BeDABCO as an efficient ligand and also a quaternary ammonium salt had an efficient stabilizing effect on the Pd(0) species in this coupling reaction. Copyright © 2015 John Wiley & Sons, Ltd.     

微波辐射下苯偶姻的干法氧化反应

研究了微波辐射下干法氧化苯偶姻生成苯偶酰的反应。结果表明，硅胶和酸性氧化铝是本反应的良好载体，空气是良好的氧化剂。在较短时间内(8～15min)即可获得很高的产率(92%～98%)，为一种有效的苯偶姻氧化反应新方法。     

Pyridine-keggin heteropoly compounds as catalyst for hydroxylation of phenol using hydrogen peroxide as oxidant

The pyridine-heteropoly compounds are very active catalysts for phenol hydroxylation to dihydroxybenzenes with hydrogen peroxide as oxidant in aqueous solutions. The conversion of phenol reaches 77.8%, and the selectivity for dihydroxybenzenes reaches 99%.     

Silica sulfate as a recyclable and efficient catalyst for Beckmann rearrangement under microwave irradiation

Silica sulfate has been proved to be an efficient and recyclable catalyst for Beckmann rearrangement of a variety of oximes in acetone under microwave irradiation. This protocol has advantages of high conversion, high selectivity, short reaction time, no environmental pollution, and simple work-up procedure.     

Zirconia-supported phosphotungstic acid as catalyst for alkylation of phenol with benzyl alcohol

The liquid-phase alkylation of phenol with benzyl alcohol was carried out using zirconia-supported phosphotungstic acid (PTA) as catalyst. The catalysts with different PTA loadings (5–20 wt.% calcined at 750 °C) and calcination temperature (15 wt.% calcined from 650 to 850 °C) were prepared and characterized by ³¹P MAS NMR and FT-IR pyridine adsorption spectroscopy. The catalyst with optimum PTA loading (15%) and calcination temperature (750 °C) was prepared in different solvents. ³¹P MAS NMR spectra of the catalysts showed two types of phosphorous species, one is the Keggin unit and the other is the decomposition product of PTA and the relative amount of each depends on PTA loading, calcination temperature and the solvent used for the catalyst preparation. The catalysts with 15% PTA on zirconia calcined at 750 °C showed the highest Brönsted acidity. At 130 °C and phenol/benzyl alcohol molar ratio of 2 (time, 1 h), the most active catalyst, 15% PTA calcined at 750 °C gave 98% benzyl alcohol conversion with 83% benzyl phenol selectivity.     

Efficient homogeneous catalysis of heteropoly acid and its characterization through etherifications of alcohol

A Keggin-type heteropoly acid revealed high catalytic activity for the etherification such as diethylene glycol with ethanol and cyclization of diethylene glycol in the homogeneous liquid. The catalytic activities of the heteropoly acid were much higher than those of conventional acid catalysts such as sulfuric acid, p-toluene sulfonic acid and phosphorous acid at the same catalyst concentrations or the same proton concentrations. On the basis of comparative measurement of electrical conductivity, acidity, and softness of anion for the solutions of acid catalysts, the efficient acid catalysis by heteropoly acid was suggested to due to be the specific properties of the heteropoly anion, which can be characterized by very weak basicity and great softness, together with the large size of the polyhedral structure.     

Green synthesis of 3,4-dihydropyrimidinones using nano Fe3O4@meglumine sulfonic acid as a new efficient solid acid catalyst under microwave irradiation

Design, synthesis and characterization of nano Fe₃O₄@meglumine sulfonic acid as a new solid acid catalyst for the simple and green one pot multicomponent synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones was studied. New solid acid catalyst was prepared through a clean and simple protocol and characterized using FTIR, VSM, TGA, SEM, elemental analysis (CHN) and XRD techniques. Heterogenization of homogeneous catalyst as a green approach is a useful method for enhancing the efficiency of catalyst. Presented study was a new method for attachment of homogeneous highly soluble catalyst (meglumine sulfate) to the magnetite nanoparticle surfaces for preparing a heterogeneous and effective catalyst. Obtained heterogeneous and reusable solid acid catalyst has high performance in the synthesis of Biginelli compounds. The reaction was performed under microwave irradiation as a rapid and green condition. Easy work up as well as excellent yield (90–98%) of products in short reaction times (40–200 s) and reusable catalyst are the main advantages of presented procedure. Reaction products were characterized in details using physical and chemical techniques such as melting point, ¹H NMR, ¹³C NMR and FTIR.     

Assembly of heteropoly acid nanoparticles in SBA-15 and its performance as an acid catalyst

Keggin‐type 12‐tungstophosphoric acid (TPA) nanocrystals have been assembled inside the pores of mesoporous silica through a vacuum impregnation method by using large‐pore SBA‐15 as a nanoreactor. The product was characterized by Brunauer–Emmet–Teller particle size distribution (BET‐PSD), NMR and FT‐IR spectroscopy, X‐ray diffraction (XRD), tranmsission electron microscopy (TEM), differential thermal analysis (DTA) and FT‐IR of adsorbed pyridine. The experimental results illustrate that the TPA nanocrystals are excellent Brønsted acid catalytic materials at room temperature.     

New environmentally-friendly solvent-free synthesis of imines using calcium oxide under microwave irradiation

Condensation of structurally diverse aldehydes including heterocyclic aldehydes, like furfural, with various amines in the presence of calcium oxide affording the corresponding imines in solvent-free conditions in good to excellent yields under microwave irradiation is described. A comparative study has been done under thermal conditions. The synergy between dry media and microwave irradiation in this reaction is evaluated by condensing less electrophilic aldehydes with poorly nucleophilic amines. The main advantages of this environmentally friendly protocol are the use of the non-toxic and inexpensive reagent calcium oxide and the considerable rate enhancement in comparison with a thermal reaction.