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91.
A simple and efficient method for the synthesis of chiral biphenylbisoxazoline ligands was developed. The bishydroxylamide precursors of ligands showed a dynamic atropselective resolution effect in the crystallization process. When biphenylbisoxazoline ligands were coordinated to tetrakis(acetonitrile)copper(I) hexafluorophosphate, it resulted in the formation of only a single diastereomer complex (S,aS,S), which behaved as a catalyst for the enantioselective allylic oxidation of cycloolefins. The enantioselectivity, yield, and rate of this reaction were optimized under different conditions, such as a change of solvents, temperature, and additives and also using various copper salts. The use of SBA-15 mesoporous silica as an additive played a crucial role in increasing the efficiency of the reaction. 相似文献
92.
Javad Zolgharnein Ghasem Shahmoradi Khosrow Zamani Saeid Amani 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(1-2):99-103
The complexation reaction of phenylaza-15-crown-5, and 4-nitrobenzo-15-crown-5, benzo-15-crown-5 and dibenzopyrdino-18-crwon-6,
dibenzo-18-crown-6,dicyclohexyl-18-crown-6(cis and trans), and 18-crown-6 with Na+ ion in methanol have been studied by potentiometric method. The Na+ ion-selective electrode has been used both as indicator and reference electrode. The stoichiometry and stability constants
of complexes of these crown ethers with sodium ion were evaluated by MINIQUAD program. The major trend of stability of resulting
complexes of these macrocycle with Na+ ion varied in the order DCY18C6 > DB18C6 > 18C6 > DBPY18C6 > phenylaza-15C5 > benzo-15C5 > 4-nitrobenzo-15C5. The obtained
results in particular stability constant of complexes of DBPY18C6, phenylaza-15C5 and 4-nitrobenzo-15C5 with sodium ion in
comparison with other crowns ether are novel, and interesting. 相似文献
93.
Khosrow Jadidi Ramin Ghahremanzadeh Peiman Mirzaei Ayoob Bazgir 《Journal of heterocyclic chemistry》2011,48(5):1014-1018
A one‐pot, three‐component method for the efficient and simple synthesis of novel 2′‐amino‐8′,9′‐dihydro‐3′H‐spiro[indoline‐3,5′‐pyrimido[4,5‐b]quinoline]‐2,4′,6′(7′H,10′H)‐trione derivatives in aqueous media is reported. J. Heterocyclic Chem., (2011). 相似文献
94.
Khosrow Zamani Shirindokht Bagheri 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1913-1918
Different types of 4,5-disubstituted 1,2,4-triazole-3-thiones were prepared by microwave irradiation as well as by a classical method. The beneficial effect of microwave irradiation on the dehydrative cyclization of thiosemicarbazides in different reaction media is described. Our results show that the effect of microwave irradiation on the reaction studied was the shortening of reaction times (from 2–9 h to 2–4 min) and a minor decrease (1–4%) in yields. The structure of the new compounds was established by FTIR, MS, and 1H NMR spectral data. 相似文献
95.
A solvent‐free reaction between urea/thiourea, dimedone and aromatic aldehydes in the presence of catalytic amounts of zirconium (IV) oxychloride octahydrate (ZrOCl2.8H2O) as a powerfull Lewis acid leads to octahydroquinazolinone/thione derivatives in good yields. This method has advantages such as avoidance of the organic solvents, production of pure products without any by‐product, short reaction times and simple operation. 相似文献
96.
A simple synthesis of novel and known calix[4]resorcinarenes derivatives has been achieved by the condensation of resorcinol and different aromatic aldehydes in the presence of catalytic amounts of Fe3O4 nanoparticles under solvent-free conditions.The experimental conditions have been thoroughly optimized and established,allowing significant rate enhancements and good to excellent yields.The reactions can be run safely without using any toxic organic solvents under mild reaction conditions.The Fe3O4 nanoparticles were characterized by powdered X-ray diffraction(XRD),transmission electron microscopy(TEM) and FT-IR spectroscopy. 相似文献
97.
A New Practical Route to ZSM‐5 Nanoparticles and Optimization of Synthetic Parameters through D‐optimal Design of Experiments 下载免费PDF全文
Saeed Soltanali Rouein Halladj Alimorad Rashidi Mansour Bazmi Saeed Khodabakhshi 《中国化学会会志》2015,62(9):817-825
A D‐optimal experimental design with three levels of SiO2/Al2O3, template/SiO2, H2O/SiO2, Na2O/SiO2 and TPABr/TPAOH ratio parameters has been used to optimize the experimental parameters by an analysis of variances (ANOVA). The effects of these ratios in the initial synthetic mixture on the size of the ZSM‐5 zeolite nanoparticles have been studied. XRD and FE‐SEM analyses were used to characterize synthetic samples. Fischer test results showed that H2O/SiO2 and TPABr/TPAOH ratios are the most and least effective parameters, respectively, in the range studied. The most important two‐way interaction variables were the interaction of template/SiO2 and TPABr/TPAOH molar ratios. The average particle size was in the 34–79 nm range. Furthermore, a mathematical model for the synthesis of ZSM‐5 zeolite nanoparticles was derived using experimental results. The optimized gel composition is as follows: SiO2/Al2O3=91.20, template/SiO2=0.16, H2O/SiO2=40.42, Na2O/SiO2=0.0147 and TPABr/TPAOH=0. 相似文献
98.
A convenient synthesis of some pyranocoumarins was described via a one‐pot, three‐component reaction of 4‐hydroxyxoumarin, malononitrile and different aromatic aldehydes in the presence of sodium tungstate. This is the first application of sodium tungstate as non‐oxidative catalyst in organic reactions. Simple operation, use of readily available starting materials, good to excellent yields and short reaction times are the advantages of this method for the synthesis of these biologically important products. 相似文献
99.
In this paper, we provide an exact analysis of a discrete-time queueing system driven by a discrete autoregressive model of order 1 (DAR(1)) characterized by an arbitrary marginal batch size distribution and a correlation coefficient. Closed-form expressions for the probability generating function and mean queue length are derived. It is shown that the system performance is quite sensitive to the correlation of the arrival process. In addition, a comparison with traditional Markovian processes shows that arrival processes of DAR(1) type exhibit larger queue length as compared with the traditional Markovian processes when the marginal densities and correlation coefficients are matched. 相似文献
100.
We introduce stochastic version of an input relaxation model in data envelopment analysis (DEA). The input relaxation model, recently developed in DEA, is useful to resource management [e.g. G.R. Jahanshahloo, M. Khodabakhshi, Suitable combination of inputs for improving outputs in DEA with determining input congestion, Appl. Math. Comput. 151(1) (2004) 263–273]. This model allows more changes in the input combinations of decision making units than those in the observed inputs of evaluating decision making units. Using this extra flexibility in input combinations we can find better outputs. We obtain a non-linear deterministic equivalent to this stochastic model. It is shown that under fairly general conditions this non-linear model can be replaced by an ordinary deterministic DEA model. The model is illustrated using a real data set. 相似文献