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| Thesis Name：Studies on stereoselective synthesis of phenylglycine using D-glucopyranosylimine as chiral template |
| Country：[CN] |
Usage：[Studies on stereoselective synthesis of phenylglycine using D-glucopyranosylimine as chiral template] |
| Remarks： |
The N-(2,3,4,6-tetra-O-pivaloyl-D-glucopyranosyl)aldimine was used as chiral template for stereoselective synthesis of phenylglycine. The phenylglycine can be synthesized stereoselectively by the tin tetrachloride lewis acid induced addition of trimethylsilyl cyanide to N-(2,3,4,6-tetra-O-pivaloyl-D-glucopyranosyl)aldimine in the dichloromethane with the addition of a small quantity of triethylamine and then by acid-catalyzed hydrolysis. The synthetic method is efficient, economical and friendly to environment, giving the high yield and high ratio of diastereomers.
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| Thesis Name：Synthesis, structure and photocatalysis of nano-TiO2 mix-crystal |
| Country：[CN] |
Usage：[Synthesis, structure and photocatalysis of nano-TiO2 mix-crystal] |
| Remarks： |
Using TiCl4 and urea as the raw materials，the mix-crystal of rutile and anatase TiO2 is prepared under 100 -150 oC by hydrothemal method. The effects of reaction pH on the ratio of nanometer TiO2 mix-crystal was also discussed. The crystal structure is determined by XRD. TEM measurement indicates that the TiO2 is spherical particles, and the average diameter of the particles is 20nm. The photocatalytic experiment show that the mix-crystal material has the best photocatalytic reactivity than the singleness TiO2. After being irradiated under the sunlight for 50 min, the compound can completely degrade the acid-red 3R.
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| Thesis Name：Efficient synthesis of dipyrromethanes and their use in the preparation of porphyrins |
| Country：[CN] |
Usage：[ Ceric ammonium nitrate, pyrrole, dipyrromethane, porphyrin] |
| Remarks： |
meso-Substituted dipyrromethanes are important precursors for the synthesis of meso-substituted porphyrins,[1] expanded porphyrins, and porphyrin analogues.[2] Several one-flask methods have been reported for the synthesis of meso-substituted dipyrromethanes by the condensation of an aldehyde and pyrrole using various combinations of acids and solvents,[3-15] such as p-Toluenesulfonic acid, propionic acid, trifluoroacetic acid (TFA) and BF3·etherate in the presencet of menthol, dichloromethane or in the absence of any other solvent, etc. These methods have afforded meso-substituted dipyrromethanes bearing many types of functional groups. However, among the above catalysts used in condensation reaction, some are expensive, some are inconvenient to use and some are of lower yield of reaction.
In recent years, ceric ammonium nitrate (CAN) has been exploited extensively in organic reactions such as oxidation, oxidative addition, nitration, photooxidation, deprotection, and graft polymerization, etc.[16] Recently Ji reported the use of CAN as a catalyst in Michael addition of indole to a,b-unsaturated ketones.[17] However, the use of CAN as a catalyst in the synthesis of dipyrromethanes under neutral conditions has not been reported. In this report we describe a condensation reaction of pyrrole with aldehydes using a catalytic amount of ceric ammonium nitrate at room temperature in the absence of any other solvent, which provides an efficient route to the synthesis of 5-substituted dipyrromethanes. |
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| Thesis Name：Studies on the mechanism of cyclocondensation of a-tosyloxylketones with selenoamides and structure characterization of 5-acetyl-2, 4-diphenylselenazole |
| Country：[CN] |
Usage：[Selenazole derivatives] |
| Remarks： |
Selenazole derivatives have antitumor, antibacterial and other notable activities. The crystal structure of 5-acetyl-2,4-diphenylselenazole that we report here displays the molecular configuration and provides an important evidence for the mechanism of cyclocondensation of a-tosyloxylketones with selenoamides
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| Thesis Name：Transport mechanism of electrolytes across charge-mosaic membrane |
| Country：[CN] |
Usage：[Transport mechanism of electrolytes across charge-mosaic membrane] |
| Remarks： |
The charge-mosaic membrane was prepared by interfacial polymerization for separating electrolytes from organics with low molecular weight. According to phenomenological equation and concentration polarization theory, a theoretical model describing membrane flux and membrane retention is established for electrolyte transport across the charge-mosaic membrane. The membrane parameters such as filtration coefficient, reflection coefficient and solute permeability are estimated. The results show that the model is in good agreement with the experimental data.
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| Thesis Name：Global geometry optimization of Na+(H2O)m clusters using a hybrid algorithm |
| Country：[CN] |
Usage：[A hybrid algorithm] |
| Remarks： |
Many recent developments in the computational technology for random search have been made in the area of atomic and molecular cluster calculations. For example, Niesse used a modified GA method to optimize the geometry of atomic and molecular clusters[1]. Greguick proposed a modified deterministic/stochastic GA method for the determination of the global minimum of (Ar)n and B(Ar)n clusters. The deterministic / stochastic GA converged more quickly to the global minimum than other random search procedures[2]. As a global optimization algorithm, the simulated annealing algorithm has been widely used to optimize the molecular clusters too[3]. But, applying all these methods to larger systems is limited. To make the random search more efficient, based on GA, FSA and CGA we have presented a hybrid optimization algorithm and applied it to water clusters in the previous works. The results showed the structures of water clusters with lower potential energy were found and a more quick optimization strategy than using other was got. So, this method is proved more effective and it can be used to optimize the structure of water clusters in the electrostatic field of sodium ion in this paper. |
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| Thesis Name：Synthesis of novel chiral quaternary ammonium salt from rosin |
| Country：[CN] |
Usage：[ammonium salt] |
| Remarks： |
Four novel chiral quaternary ammonium salts were synthesized from naturally occurring disproportionate rosin amine by isolation, methylation and alkylation. The products were synthesized with yield of 69%-93%. The target compounds were identified with FT-IR, NMR and MS.
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| Thesis Name：The fluorescence characteristic of the aluminium(Ⅲ)-fleroxacin system and its analytical application |
| Country：[CN] |
Usage：[analysis] |
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In this paper, a simple, rapid and sensitive spectrofluorimertic method based on the formation of aluminium complexes has been developed for the determination of Fleroxacin (FLX). The factors of affecting the fluorescence intensity were studied in detail. Under optimum conditions, a linear relationship was obtained between the fluorescence intensity and the FLX concentration in the range 1.0×10-9-5.0×10-6 mol/L, and the detection limit of FLX was 7.4×10-11 mol/L (S/N=3). The method is applied for the determination of FLX in actual sample, and the result obtained is satisfactory。
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| Thesis Name：Synthesis of derivatives of 2, 3, 5, 6-tetrachloromethylbenzene |
| Country：[CN] |
Usage：[Synthesis] |
| Remarks： |
Synthesis of derivatives of 2, 3, 5, 6 - tetrachloro- methylbenzene with electron withdrawing groups was studied. Chlorination could not occur when there were two electron withdrawing groups in the para positions of benzene under designed condition. But if one of them was electron donating group such as methyl, high yield of chlorinated products could be gained in carbon tetrachloride and chlorosulphonic acid at a temperature from 50ºC to 55ºC, and catalyzed by iodine. The products were 2, 3, 5, 6-tetrachloro-4-methylbenzonitrile with yield of 96.3%, 2, 3, 5, 6 - tetrachloro-4- nitrotoluene with yield of 85.5%, 2, 3, 4, 5, 6-pentachloromethylbenzene with yield of 84.2%, and methyl 2, 3, 5, 6-tetrachloro-4-methylbenzoate with yield of 62.1%.
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| Thesis Name：Addition curing type silicone resin composition |
| Country：[CN] |
Usage：[chemical industry] |
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An addition curing type silicone resin composition is provided including (A) 100 parts by weight of a specific organopolysiloxane with a phenyl group and at least two alkenyl groups within each molecule, (B) 1 to 100 parts by weight of a specific organohydrogenpolysiloxane with a phenyl group and at least two SiH groups within each molecule, and (C) an effective quantity of a hydrosilylation reaction catalyst. A cured product obtained by curing this composition is transparent, displays good strength and particularly good flexural strength, and moreover also displays a high degree of hardness. The composition is applicable to a variety of fields including electrical and electronic equipment, OA equipment and precision instruments. |
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