PEG-400介质中L-脯氨酸催化香豆素-3-羧酸乙酯的合成

用PEG-400为溶剂,L-脯氨酸作为催化剂,能高效简便地催化水杨醛与丙二酸二乙酯通过Knoevenagel缩合反应得到香豆素3-羧酸乙酯.本方法具有易于操作,后处理方便,反应时间较短,反应收率较高,催化剂和溶剂价廉易得,而且环境友好等优点.     

Acoustical study of molecular interactions in polymer solutions through various thermodynamical parameters and Flory's theory at 298.15 K

This study intends to portray the nature of polymer solutions by ultrasonic velocity and density data. Acoustical parameters, such as relaxation strength, relative association, molecular constant, fractional free volume, available volume, Beyer's non-linearity parameter, internal pressure, van der Waals’ constants and molecular radius have been computed for the binary mixtures of PEG400?+?methanol, PEG400?+?ethanol, PPG400?+?ethanol and PPG400?+?2-propanol systems at 298.15?K. Flory's theory has been used for computing ultrasonic velocity, surface tension, thermal expansion coefficient, thermal conductivity, excess heat capacity and excess isothermal compressibility. Isothermal compressibilities of mixtures have been theoretically evaluated using different theories. A new relation has been proposed by us for evaluating excess molar volume using ultrasonic velocity of the mixture which gives fairly good result when compared with the experimental values. Excess molar volume has been calculated using Flory's theory and Prigogine–Flory–Patterson theory. The partial molar volume and its excess value at infinite dilution have also been evaluated.     

Online measurement of the BEPC Ⅱ background using RadFET dosimeters

To monitor the integral dose deposited in the BESⅢ electromagnetic calorimeter whose perfor-mance degrades due to exposure to the BEPCⅡ background, a 400 nm IMPL RadFET dosimeter-based integral dose online monitor system is built. After calibration with the 60Co source and verification with TLD in the pulse radiation fields, an experiment was arranged to measure the BEPC Ⅱ background online. The results are presented.     

PEG-400为绿色反应介质无催化一锅法合成2-氨基-3-氰基-4-芳基-4H-苯并色烯衍生物

PEG-400为绿色反应介质下无催化萘酚、丙二腈及芳香醛三组分“一锅法”高产率地得到了苯并色烯衍生物. 该反应具有产率高、污染少、操作简单、环境友好等优点, 产物的结构通过红外光谱和核磁共振谱进行了表征.     

L-proline catalyzed multicomponent domino reaction in polyethyleneglycol-400 for regioselective synthesis of pyrazolyl-tetrahydroindazolones under microwave irradiation

A simple and convenient approach for the synthesis of pyrazolyl-tetrahydroindazolones via L-proline catalyzed three component domino reaction of arylhydrazine, dimedone and pyrazole aldehyde in polyethyleneglycol-400 (PEG-400) under microwave irradiation is described. This novel and green protocol proceeds smoothly in good to excellent yields and provides several advantages such as shorter reaction time, metal-free reaction conditions, simple work-up procedures. Also, recycling of the catalyst and solvent was observed without the loss of activity for three (03) runs.     

Synthesis of homo-propargylic ethers: A domino ring opening/coupling reaction of oxiranes with terminal alkynes and aryl iodides

A domino ring opening/cross-coupling reaction of oxiranes with terminal alkynes and aryl iodides has been developed. This transformation serves as a protocol for the synthesis of homo-alkyne ether skeletons from the readily available starting materials. The success of the reaction has dependence on catalyst/ligand system of choice. The synthesis utility of the alkyne ether skeletons in formation of chromane skeleton has also been studied.     

A green and efficient method for synthesis of benzimidazoles using nano‐Fe3O4 in PEG‐400/H2O aqueous system under ambient conditions at room temperature

In this paper, a green and facile protocol was described which was efficient for synthesis of benzimidazoles using nano‐Fe₃O₄ catalyst with continuous bubbling of air as the oxidant in PEG‐400/H₂O aqueous system at room temperature. This protocol afforded the target products in good to excellent yields and the catalytic system could be recycled and reused without significant loss of catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Sensitized multiphoton dissociation of UF6 IN SF6-UF6 mixtures by a tea CO2 laser

UF₆ undergoes decomposition in the presence of SF₆ when mixtures of both are irradiated with a TEA CO₂ laser. The mechanism for UF₆ decomposition may involve vibrational energy transfer from excited SF₆ and laser absorption from the same laser pulse by excited UF₆ in its vibrational quasi-continuum     

Facile one-step sonochemical synthesis of ultrafine and stable fluorescent C-dots

This work describes a one-step synthesis of carbon dots (C-dots), which is carried out by sonication of polyethylene glycol (PEG-400) for 0.5–3 h. The effect of the various experimental parameters, such as sonication time, amplitude and temperature on the size and the fluorescence of the C-dots was studied. It was found that the average diameter of the C-dots is between 2 and 9 nm, depending on the preparation conditions. The highest quantum yield of emission was ∼16%. These high fluorescence properties of the C-dots could be used for bioimaging and for solar cell applications.     

A rapid,mild, and efficient method for C-5 iodination/thiocyanation of 2-aminothiazoles

An efficient, green, rapid multitasking protocol for the selective C-5 substitution of 2-aminothiazole using iodic acid and aqueous PEG-400 was developed. The method found suitable for C-5 substitution i.e. iodination and thiocyanation of 2-amino thiazole using iodine and ammonium thiocyanate respectively. Iodic acid was found to be a good oxidant and aqueous PEG-400 as green reaction solvent.