Summary. Reaction of triphenylphosphine and an electron deficient acetylenic ester in the presence of strong N–H acid such as alkyl
and aryl sulfamides or acetamide produces phosphorous ylides at room temperature in CH2Cl2. The aryl sulfamide phosphoranes undergo a smooth transformation reaction in boiling toluene and produce iminophosphoranes. 相似文献
In this study, natural‐based ionic liquid (IL) using caffeine (Caff), trietahnolamine (TEA) and ZnBr2, [Caff‐TEA]+[ZnBr3]?, which features high catalytic activity and environmentally‐friendly nature was synthesized with melting point of 76 °C by a facile method. The synthesized [Caff‐TEA]+[ZnBr3]? has high catalytic activity as both of catalyst and solvent in condensation reactions for the synthesis of benzylidenes, bis‐hydroxyenones and xanthenes. Synthesized IL was characterized by proton nuclear magnetic resonance (1HNMR), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD) and Energy‐dispersive X‐ray spectroscopy (EDX) analysis. Also synthesized heterocycles were characterized by FT‐IR, proton nuclear magnetic resonance (1HNMR) and carbon nuclear magnetic resonance (13CNMR). 相似文献
A number of new dialkyl 2‐(alkyl or aryl)‐6‐(pyrimidin‐2‐ylthio)‐4‐thioxo‐5,6‐dihydro‐4H‐1,3‐oxazine‐5,6‐dicarboxylate have been prepared in good yield from the multicomponent reaction between 2‐mercaptopyrimidines and acetylenic diesters with acetyl or benzoyl isothiocyanate. 相似文献
In this study, a simple and efficient method of ligandless-ultrasound-assisted emulsification microextraction (LL-USAEME) followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) has been developed for simultaneous extraction, preconcentration and determination of manganese, cadmium, cobalt and nickel in water samples. In the proposed approach, tetrachloroethylene was selected as extraction solvent. The effect of important experimental factors such as volume of extraction solvent, pH, sonication time, salt concentration, and temperature was investigated by using a fractional factorial design (25?1) to identify important factors and their interactions. In the next step, a Box-Behnken design (BBD) was applied for optimisation of significant factors. The obtained optimal conditions were: 30?µL for extraction solvent, 12 for pH, 5?min for sonication time, and 5% w/v for salt concentration. The limits of detections (LODs) for Cd(II), Co(II), Mn(II) and Ni(II) were 0.20, 0.13, 0.21 and 0.28?µg?L?1, respectively. Relative standard deviations (RSD, C?=?200.0?µg?L?1, n?=?9) were between 3.4–7.5% and the calibration graphs were linear in the range of 0.25 to 1000.0?µg?L?1 for Mn, 0.5–1000.0?µg?L?1 for Co and Ni and 1.0–250.0?µg?L?1 for Cd. The determination coefficients (R2) of the calibration curves for the analytes were in the range of 0.993 to 0.999. The proposed method was validated by using two certified reference materials, and also the method was applied successfully for the determination of heavy metals in different real water samples. 相似文献
Using both classical reflux and microwave-mediated conditions, a series of new spiroindoloindolizidines was synthesized by multicomponent 1,3-dipolar cycloaddition of azomethine ylides in unprecedented exo/endo stereocontrolled. Both conditions easily afforded two identical and separable exo/endo diastereomeric ratios of cycloadducts. However, the ratio of two diastereomeric products obtained from conventional conditions was reversed in all examined cases when the reactions were explored under microwave-mediated conditions. As expected, utilizing the microwave-assisted conditions produced higher yields and reaction rates compared to classical conditions. The structure and exact stereochemistry of synthesized cycloadducts were determined by applying various 2D-NMR spectroscopic techniques and single-crystal X-ray diffraction. Finally, the mechanism of the reaction has been briefly investigated by using density functional theory (DFT) calculations. 相似文献
In this paper, an experimental study, aimed at delaying flow separation on a high-lift device using a pulsed blowing excitation method, is reported. The main objective of this investigation was to evaluate a new pulsed jet generation strategy to enhance flow control performance. In these experiments, two types of signal waveform were implemented to produce the unsteady blowing; a simple square-wave excitation signal for the first case, and a burst modulated excitation signal for the second case. The signal modulation was the first time to be used for a fast-switching solenoid valve actuator. Another objective of this study was to evaluate a new arrangement of the jet exit slots, in the form of a vortex generator which was employed for the first time on the high-lift device. For this purpose, a NASA SC(2)-0714 airfoil with a single slotted flap was employed. The vortex generator jets emanated from the shoulder of the trailing-edge flap with excitation frequencies from 40 to 1000 Hz. Pressure distribution around the model and wake total pressure deficit were measured. The results indicated that ejection from vortex generator slot pairs was able to prevent flow separation completely in most conditions. These measurements revealed that the burst modulated excitation signal was accompanied by more aerodynamic improvements and less air consumption relative to the simple pulsed jet excitation signal. In the best flow control mode, the results showed about a 53% increase in the value of the suction pressure peak on the flap and a 38% decrease in drag with a reduction in total pressure loss.
A series of novel organosoluble polyamides (PAs) bearing different functional groups such as flexible ether, substituted imidazole, and xanthene rings and electron-withdrawing CF3 groups were synthesized from diamines and various dicarboxylic acids. The structures of diamines and PAs were fully characterized by elemental analysis, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy. The PAs showed good solubility in aprotic and polar organic solvents, with high thermal stability exhibiting the glass transition temperatures (Tgs) and 10% weight loss temperatures (T10%) in the range of 184–277°C and 410–480°C in N2 atmosphere, respectively. These polymers showed fluorescence emission upon irradiation with UV light. Diamine compounds and two of synthesized polymers were also screened for antibacterial activity against gram-positive and gram-negative bacteria, and the obtained results for all four combinations showed good inhibition. Extraction capability for heavy metal ions such as Cr3+, Pb2+, Hg2+, Cd2+, and Co2+ from aqueous solutions was also tested at 25°C and pH 7–8. 相似文献
The water-soluble Ni(II) complex, [Ni(bipy)2(phen-dione)](OAc)2·2H2O (bipy = 2,2′-bipyridine and phen-dione = 1,10-phenanthroline-5,6-dione) has been synthesized and characterized by physico-chemical
and spectroscopic methods. The binding interactions of this complex with calf thymus DNA (CT-DNA) were investigated using
fluorimetry, spectrophotometry, circular dichroism and viscosimetry. In fluorimetric studies, the enthalpy and entropy of
the reaction between the complex and CT-DNA showed that the reaction is exothermic (ΔH = −123.9 kJ mol−1; ΔS = −323.5 J mol−1 K−1). The competitive binding studies showed that the complex could not release methylene blue completely. The complex showed
absorption hyperchromism in its UV–Vis spectrum with DNA. The calculated binding constant, Kb obtained from UV–Vis absorption studies was 2 × 105 M−1. Moreover, the complex induced detectable changes in the CD spectrum of CT-DNA, as well as changes in its viscosity. The
results suggest that this nickel(II) complex interact with CT-DNA via a groove-binding mode. 相似文献