Decomposition Reaction of Zn-MPA(3-Mercaptopropionic Acid) Complex Under Microwave Irradiation

The thermal decomposition of Zn-MPA complex was investigated under microwave irradiation. ZnO and ZnS nanocrystals could be obtained by decomposing Zn-MPA（3-mercaptopropionic acid） complex under different reaction conditions. It was found that both the pH value of the solution and the molar ratio of Zn2＋ and MPA can play an important role in the formation of ZnO and ZnS nanocrystals. MPA mainly acts as an S source or as a complexing agent. This study provides a new route for the controllable preparation of semiconductor nanocrystals.

Heck Reactions with Ultralow Concentration of Transition Metals under Microwave Irradiation

The Heck coupling reactions of aryl halides and olefins were performed under the microwave assistance. Interestingly, the ultralow concentration of transition metals (in ppb) coming from the reactants could catalyze the Heck coupling reactions under microwave irradiation, without addition of any catalysts, ligands and phase-transfer agents. The influences of bases, solvents and temperature were discussed, and the reaction rate was enhanced largely in the mixed solvents of NMP and water due to the solubility of base in water.

Microwave Irradiation Effect on Intermolecular and Intramolecular Friedel-Crafts Acylation Reaction

The effect of microwave irradiation on the intermolecular and intramolecular Friedel-Crafts acylation of aromatic compounds was investigated. Microwave irradiation had no effect on the intermolecular reaction but had an accelerating effect on the intramolecular reaction. This enhanced intramolecular reactivity that was attributed to the high probability of close proximity between the reaction sites.

Facile and efficient synthesis of quinoline-4-carboxylic acids under microwave irradiation

A facile and efficient method for the preparation of 2-non-substituted quinoline-4-carboxylic acids is described via the Pfitzinger reaction of isatins with sodium pyruvate following consequent decarboxylation under microwave irradiation.

Preparation of poly(amino-quinone) by microwave-assisted solid-state polymerization

Microwave irradiation was employed to assist the synthesis of poly（amino-quinone） （PAQ） from p-benzoquinone and diamines in solid state. The effects of power, time, and pattern （continuously or intermittently） of microwave irradiation on yield and intrinsic viscosity of PAQs were studied. It is shown that the continuous microwave irradiation at a high power leads to rapid increase of yield and a sudden halt in polymerization afterwards, due to the subsequent loss of volatile reactants at a high reaction temperature. Alternatively, the high-power microwave irradiation is applicable to raising the yield if used intermittently. In contras4 the low-power microwave irradiation favours the way of continuous exposure to ensure sufficient heat for polymerization. In both cases of high and low power, the yield and intrinsic viscosity can be further promoted by prolonging the exposure time. It is found that under a preliminarily optimized condition of intermittent irradiation at 490 W with six sequences of 5 min irradiation followed by 5 rain interval, the yield and intrinsic viscosity of PAQ from p-benzoquinone and p-phenylene diamine can reach as high as 83% and 41.9 mL/g, respectively.

Effect of Microwave Irradiation on Friedel-Crafts Diphenylmethylation of Arenes

The reaction between diphenylmethanols and substituted benzenes is useful to yield triarylmethane derivatives which are important skeletons in various functional materials and biologically relevant substances. The Reactions were carried out under microwave irradiation as environmentally-friendly method. In cyclohexane, the reaction was accelerated under microwave irradiation as compared to under conventional heating. Also, when more than 0.8 equivalents of iron(III) chloride were used, the acceleration was observed. Notably, when iron(III) chloride and arenes were combined, the temperature of the reaction solution rose to 40°C. It is considered that a chemical species was formed upon coordination of iron(III) chloride to the diphenylmethanols or arenes.

Rapid Microwave-promoted Base-free Suzuki Coupling Reaction of Sodium Tetraphenylborate with Hypervalent Iodonium Salts in Water

The palladium chloride-catalyzed Suzuki coupling reaction of sodium tetraphenylborate with hypervalent iodonium salts was achieved under microwave irradiation in water without base in excellent yield. A convenient and rapid method for formation of carbon-carbon bonds was afforded.

Microwave-assisted Palladium-micelle-catalyzed Suzuki Cross-coupling Reaction in Water

A microwave-accelerated Suzuki coupling procedure was developed via guanidinium ionic liquids（GILs） stabilized Pd-micelle.The Pd micelle/GILs play a key role in enhancing the activity,due to the highly dispersed Pd active sites and the phase transfer function of GILs,which ensures the adsorption of reactants and facilitates the translation of the intermediates to the surface of the micelle.

Microwave-assisted one-pot synthesis of 3-substituted-3,4-dihydrocoumarins via tendem Konevenagel and Hantzsch reactions

A convenient route for the synthesis of 3,4-dihydrocoumarin derivates from salicylaldehyde derivates and 1,3-dicarbonyl compounds under solvent-free microwave irradiation conditions was described. In this way, a range of compounds was obtained in moderate to good yields in a short reaction time.

Microwave-assisted aldol condensation of benzil with ketones

Under microwave irradiation, the corresponding hydroxycyclopentenones were prepared in high yields by the cross-aldol reactions of benzil with various ketones. When the reactions were performed in various solvents under classical heating for a long time, they produced the products in relatively low yields.

Microwave Assisted Synthesis of 3,3',3″,3'″-o-,p-Phenylenedi-methylidinetetrakis-(4-hydroxy-2H-1-benzopyran-2-one)

Under microwave irradiation,2,2＇-alkoxy-bridging or 4,4＇-alkoxy-bridging dibenzaldehydes reacted with 4-hydroxycoumarin in DMF to give a series of 3,3＇,3″,3＇″-o-and 3,3＇,3″,3＇″-p-phenylenedimethylidinetetrakis-（4-hydroxy-2H-1-benzopyran-2-ones） in moderate yields.The structures of the synthetic coumarin derivatives were characterized with IR,1H NMR and MS spectroscopy as well as X-ray single crystallography.

Microwave-assisted base-free synthesis of trans-cinnamic acids using hypervalent iodonium salts

A fast and convenient base-free Heck reaction of acrylic acid with hypervalent iodonium salts was achieved under microwave irradiation in water, providing a simple method for the synthesis of trans-cinnanfic acids in good yields in short time.

可控微波促进对称1,n-亚甲基二酯的环境友好合成

采用可控微波加热技术,在水作溶剂或无溶剂条件下芳甲酸与1,n-二溴代烷发生双酯化反应,“一锅”法高效地合成了系列亚甲基二羧酸酯类化合物.考察了反应温度、时间、碱、溶剂对双酯化产率的影响,在优化实验条件下合成了31种亚甲基二羧酸酯,底物适用范围广,并提出了合理的反应机理.该方法操作简单、时间短,产率较高,同时符合绿色化学的原则.

强吸波催化剂协同微波能强化果糖脱水制5-羟甲基糠醛

利用硬模板法制备了中空多孔碳球(MHCS),系统研究了热处理温度、金属负载量、刻蚀前后对MHCS电磁参数的影响。从中选取高介电损耗值(ε″)的MHCS-800(ε″=213)作为催化剂载体,并以SCS-800(ε″=50)和SCS(ε″=0.08)作为对比样品,经磺化后用于催化果糖水解制5-羟甲基糠醛,根据在微波加热和常规油浴条件下的反应动力学探究了ε″对微波催化效果的影响。结果表明,在80 W微波功率辐照下使用MHCS-800-SO_(3)H作为催化剂,5 min转化率即可达97.7%;反应速率常数(k)为0.76 min^(-1),是常规加热(k=0.0847 min^(-1))的8.97倍,该催化剂相较于SCS-800-SO_(3)H和SCS-SO_(3)H的微波催化效果(k比常规分别提升了164.9%、11.9%)更加显著。以上研究结果源于中空多孔结构和高的石墨化程度相耦合更有利于在催化剂颗粒表面形成“热点”,从而加速催化反应。

Solid-state reaction induced defects in multi-walled carbon nanotubes for improving microwave absorption properties

Dielectric polarization performance induced by defect engineering approach has been proved to be an effective way for improving the microwave absorption property of carbon-based materials.Assisting by the solid-state reaction,the structural integrity of multi-walled carbon nanotubes(MWCNTs)would be broken along with the volume expansion and etching process of cobalt oxides.Therefore,the defects could be obtained and result in the enhancement of microwave absorption property.Ascribing to the broken wall structures,the defect-distances(L_(D))and concentrations(n_(D))have been optimized to be 9.80 nm and3.37×10^(11) cm^(-2).The minimum reflection loss(RL)had reached-54.6 dB at 4.5 GHz with a thickness of4.13 mm and the corresponding effective absorption bandwidth(EAB_(<-10 dB))was analyzed to be 14.6 GHz.Such enhancement is correlated to the dielectric polarization and the permeability-to-permittivity transformation raised from the defect structures and concentrations.The present work demonstrates an effective strategy for tailoring the microwave absorption property of MWCNTs by engineering defect concentrations,and could be further extended to other carbon-based absorbents.

微波与离子液体协同催化高效合成1,4-二氢吡啶类化合物

在以吡啶为母体的离子液体和微波辐射协同催化下,以醋酸铵、间硝基苯甲醛和3-氧代-N-苯基丁酰胺为原料,通过Hantzsch反应一锅合成2,6-二甲基-4-3ˊ-硝基苯基-N3,N5-二苯基-3,5-二甲酰胺-1,4-二氢吡啶化合物,产物结构通过1H-NMR表征进行了确认。与文献中描述的方法相比,该方法具有反应过程简单、反应时间短、收率高、催化剂易重复使用等优点。

Rare-Earth Metal Chlorides Catalyzed One-pot Syntheses of Quinolines under Solvent-free Microwave Irradiation Conditions

Under microwave irradiation and solvent-free conditions, rare-earth metal chlorides （RECl3） have been efficient catalysts for one-pot synthesis of quinoline derivatives to give products in good to excellent yields through the mul- ti-component reactions of aldehydes, amines, and alkynes. The rare-earth metal chlorides can be recycled for six times without notable loss of catalytic activities. This new synthetic approach has prominent features of a short re- action time, high yields of products, operational simplicity, broad substrate scopes, environmentally friendly prop- erty and commercially available catalysts. It extends the applications of rare-earth metal compounds as catalysts in organic synthesis.

Synthesis of 14-Fluorophenyl-14H-Dibenzo[a,j]xanthenes and Their Derivatives under Microwave Irradiation and Solvent-free Conditions

A facile and efficient synthesis of 14-fluorophenyl-14H-dibenzo[a,j]xanthenes has been developed by one-pot condensation of fluorinated benzaldehydes with β-naphthol in the presence of p-TSA·H2O under microwave irradiation and solvent-free conditions. These products are conveniently oxidized to 14-fluorophenyl-14-hydroxydibenzo[a,j]xanthenes by PbO2 in acetic acid in good yields.

Rapid Synthesis of 1,2,3,4-Tetrahydropyrimidin-2-ones Using Zn（NH2SO3）2 as a Catalyst under Microwave Irradiation

Rapid synthesis of 1,2,3,4-tetrahydropyrimidin-2-ones （THPO） from aromatic aldehydes, β-ketoester and urea （or thiourea） using zinc sulfamate as the catalyst under microwave irradiation was described here. Compared with the classical Biginelli reaction, this new method consistently has the advantages of good yields （76%-96%）, short reaction time （3-15 min）, no corrosion to equipments, ease of manipulation, and low cost catalyst.

New Method for the Synthesis of 1-Methylimidazolium Trifluoroacetate and Its Application in Biginelli Reaction

A new method for the synthesis of 1-methylimidazolium trifluoroacetate ([Hmi]Tfa), a protic ionic liquid (PIL), under ultrasonic irradiation has been developed. In addition, the product [Hmi]Tfa was successfully employed as solvent and catalyst in Biginelli reaction to prepare 3,4-dihydropyrimidinones (DHPMs) in high yield under mild reaction conditions.