排序方式: 共有225条查询结果,搜索用时 15 毫秒
1.
Molecular Diversity - This study describes the use of 3-aminotriazole, different aldehydes and N-methyl-1-(methylthio)-2-nitroethenamine as a ketene N,S-acetal in a three-component condensation for... 相似文献
2.
Shamsipur M Chaichi MJ Karami AR 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(3):511-517
The chemiluminescence arising from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with hydrogen peroxide in the presence of acriflavine has been studied. The relationship between the chemiluminescence intensity and concentrations of TCPO, H2O2, acriflavine and the base sodium salicylate are reported. The kinetic parameters for the peroxyoxalate-chemiluminescence (PO-CL) of acriflavine were evaluated from the computer fitting of the corresponding chemiluminescence intensity-time plots. 相似文献
3.
Urea-hydrogen peroxide (UHP) was used in the presence of maleic anhydride as mediator in a simple and convenient method for the oxidation in high yield of some thiols to the corresponding disulfides. Peroxymaleic acid formed in situ from the reaction of UHP with maleic anhydride has a key role in this oxidation. Performance of the reaction in various solvents showed that methanol was the solvent of choice at 0 oC. The products were isolated by simple filtration on silica gel. 相似文献
4.
Bahador Abolpour Roozbeh Abolpour Arash Shamseddini Saideh Kamyabi Farahnaz Hamzehee 《Research on Chemical Intermediates》2013,39(2):681-692
In this paper, the enthalpy-concentration method was applied in order to model a steady-state continuous methanol–water mixture distillation column. This work includes three steps; first, to develop a code in MATLAB v.7.6 to apply to the mathematical model of the column. The second step is to simulate the column using HYSIS v.3.2. While the third is the calculation of the optimized reflux ratio to minimize the operating cost. For a distillation tower such as the methanol–water splitter in this study, there are relatively few degrees of freedom that can be manipulated in order to minimize operating costs; the reflux ratio can influence the steady-state operating point and therefore the daily costs. In this paper, we have discussed the trade-offs between reflux ratios and operating costs. A correlation is derived to define the optimum value of the reflux ratio as an exponential function of a certain economic parameter of energy prices and depreciation costs. We demonstrate that, at low energy prices or high equipment depreciation costs, the optimum reflux factor is high. 相似文献
5.
Hossein Filian Alireza Kohzadian Masoud Mohammadi Arash Ghorbani-Choghamarani Amirali Karami 《应用有机金属化学》2020,34(6):e5579
In this research, a rapid, green and efficient protocol for synthesis of bis (pyrazolyl)methane derivatives in the presence of Pd(0)-guanidine@MCM-41 catalysts under solvent-free conditions by the following two methods has been reported: (i) via the one-pot pseudo five-component reaction among phenylhydrazine (2 equivalents), ethyl acetoacetate (2 equivalents) and aromatic aldehydes (1 equivalent); and (ii) the one-pot pseudo three-component reaction between 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (2 equivalents) and aromatic aldehydes (1 equivalent). Some advantages of this protocol include: green conditions, extremely short times, high efficiency, proper one-pot operation, generality of method, easy work-up and recyclability, and reusability of the catalyst up to five times without significant loss in catalytic activity. 相似文献
6.
Reaction pathways of ethylene and carbon monoxide on the singlet and triplet potential energy surfaces (PESs) have been calculated at B3LYP/6-311++G (3df, 3dp), G3B3 and CCSD(T)//B3LYP levels. Reaction mechanisms have been investigated by analysis of various structures. Suggested reaction mechanisms reveal that 3P3(CH2CHCHO) and 3P4(CH3CCHO) are thermodynamically stable adducts with the negative value in Gibbs free energies on the triplet PES. In addition, results show that one intersystem crossing exists between triplet and singlet PESs, which are obtained by scanning of the C–C bond length in 1IN3 and 3IN7 species. 相似文献
7.
Bahador Abolpour Benafsheh Abolpour Roozbeh Abolpour Hossein Bakhshi 《Research on Chemical Intermediates》2013,39(2):707-719
Concrete mix design is a process of proportioning the ingredients in right proportions. The aim of this study is to design a fuzzy logic model for determination of the compressive strength of a concrete. The datasets which have been loaded into a fuzzy logic model contain 1,030 concrete mixtures. Input fields of the fuzzy expert system are weight percent of cement, water, blast furnace slag, fly ash, super plasticizer, fine aggregate, coarse aggregate, and age of the concrete. Output field is concrete compressive strength. Finally, 897 rules used for this fuzzy logic modeling. 相似文献
8.
N. Iranpoor H. Firouzabadi H. Bahador A. Jamalian 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1972-1978
Silicaphosphite (silphos), [PCl3-n(SiO2)n], as a heterogeneous phosphorous compound, catalyzes the thiocyanation of benzylic alcohols and silyl and THP ethers in the presence of I2 and NH4SCN in refluxing CH3CN. The produced silphos oxide byproduct can be easily separated by a simple filtration. Silphos is also used for the efficient and selective deprotection of silyl and THP-ethers to their corresponding alcohols. 相似文献
9.
A combination of molybdatophosphoric acid and NaNO2 in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of 1,2‐dihydroquinolines to their corresponding quinoline derivatives in dichlomethane at room temperature with excellent yields. 相似文献
10.
The activity of [Pd(C6H4CH2 NH2‐κ2‐C‐N)PPh3MOBPPY]OTf complex, A (MOBPPY = 4‐methoxybenzoylmethylenetriphenyl‐ phosphoraneylide), was investigated in the Heck–Mizoroki C? C cross‐coupling reaction under conventional heating and microwave irradiation conditions. The complex is an active and efficient catalyst for the Heck reaction of aryl halides. The yields were excellent using a catalytic amount of [Pd(C6H4CH2 NH2‐κ2‐C‐N)PPh3MOBPPY]OTf complex in N‐methyl‐2‐pyrrolidinone (NMP) at 130 °C and 600 W. In comparison to conventional heating conditions, the reactions under microwave irradiation gave higher yields in shorter reaction times. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. 相似文献