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141.
Ujjal Kanti Roy 《Tetrahedron》2006,62(4):678-683
A simple and highly efficient one-pot procedure for allylation and propargylation of arylepoxides has been developed. A combination of SnCl2 and catalytic Pd(0) or Pd(II) promotes the reaction of organic halides and epoxides in DMSO with controlled water addition, leading to the regioselective formation of the corresponding homoallyl and homopropargyl alcohols in good yields. 相似文献
142.
Angelika Basch Silvia Gross Namita Roy Choudhury Janis Matisons 《Journal of Sol-Gel Science and Technology》2005,33(1):39-45
New inorganic-organic hybrid materials were prepared by free-radical polymerization of methyl methacrylate (MMA) with methacrylate-substituted oxotantalum cluster [Ta4O4(OEt)8(OMc)4] and their properties evaluated. The cluster was prepared by the reaction of the parent alkoxide with methacrylic acid. Samples of the hybrid materials were produced with Ta-cluster to methyl methacrylate in the ratios of 1:50 and 1:100 and were characterized by thermal and spectroscopic techniques. The glass transition temperatures of the hybrid materials are shifted to higher temperatures than pure PMMA as a result of cross-linking of the polymer by the oxotantalum clusters. The increase in Tg is also observed from the dynamic mechanical analysis (DMA). Evidence of crosslinking between the Ta-cluster and PMMA is obtained from infrared spectroscopic study. Surface studies performed by X-ray photoelectron spectroscopy (XPS) provide information about the atomic concentrations of the surface and indicate tantalum bonded to oxygen. 相似文献
143.
Summary The organofunctional trisiloxanes Me3SiOSiMe(R)OSiMe3 [R=(CH2)2PPh2, (CH2)3C5H4N, (CH2)3CN, (CH2)2Ph, (CH2)2SPh, CH=CH2 and CH2CH=CH2] have been reacted with metal halide and-carbonyl moieties in order to determine the coordination preferences of materials being used as models for metallated longchain linear functionalised polysiloxanes. The products [Me3SiOSiMe(R)OSiMe3]3MLn [R=(CH2)2PPh2, MLn=RhCl],cis-[Me3SiOSiMe(R)OSiMe3]2MLn [R=(CH2)2PPh2 or (CH2)3C5H4N, MLn=Mo(CO)4],trans-[Me3SiOSiMe(R)OSiMe3]2MLn[R=(CH2)2PPh2, MLn=NiCl2, PdCl2, PtCl2 and [Rh(CO)Cl] and [Me3SiOSiMe(R)OSiMe3]MLn [R=(CH2)2PPh2, MLn=Mo(CO)3(2,2-bipyridine); R=(CH2)2Ph, MLn=Mo(CO)3; R=(CH2)3C5H4N, (CH2)3CN, or (CH2)2SPh, MLn=Rh(CO)2Cl; R=CH=CH2 or CH2CH=CH2, MLn=Fe(CO)4] have been isolated and characterised spectroscopically in the course of these studies. 相似文献
144.
Rabindra N. Roy Jill Cramer Victoria Randon Demara Willard Jennifer L. Walter William S. Good Amanda Kilker Lakshmi N. Roy 《Journal of solution chemistry》1998,27(5):425-434
The second acidic dissociation constants pK
2 of the ampholyte N-(2-hydroxyethyl) piperazine-N-2-hydroxypropanesulfonic acid (HEPPSO) have been determined at seven temperatures from 5 to 55°C from emf measurements utilizing hydrogen and silver–silver chloride cells without liquid junction. The thermodynamic quantities, G°, H°,S°, and C
p
o
have been calculated from the temperature coefficient of pK
2. At 25°C, the pK
2 = 8.042 and at 37°C, pK
2 = 7.876; hence, buffer solutions of HEPPSO and NaHEPPSOate are important for pH control in the region close to that of clinical fluids (blood serum). Conventional pH values from 5 to 55°C as well as those obtained from liquid junction correction at 25 and 37°C have been reported for three buffer solutions with the compositions (molality scale): (1) equimolal mixture of HEPPSO (0.04 m) + NaHEPPSOate (0.04 m) + NaCl (0.12 m); (2) HEPPSO (0.08 m) + NaHEPPSOate (0.08 m); and (3) HEPPSO (0.08 m) + NaHEPPSOate (0.08 m) + NaCl (0.08 m). 相似文献
145.
A solvent tolerant Pseudomonas aeruginosa PseA strain was isolated from soil. It secreted a novel alkaline protease, which was stable and active in the presence of range of organic solvents, thus potentially useful for catalysis in non-aqueous media. The protease was purified 11.6-fold with 60% recovery by combination of ion exchange and hydrophobic interaction chromatography using Q-Sepharose and Phenyl Sepharose 6 Fast Flow matrix, respectively. The apparent molecular mass based on the sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was estimated to be 35,000 Da. The enzyme was stable in the pH range of 6.0-9.0, the optimum being 8.0. The Km and Vmax towards caseinolytic activity were found to be 2.7 mg/ml and 3 micromol/min, respectively. The protease was most active at 60 degrees C and characterized as a metalloprotease because of its sensitivity to EDTA and 1,10-phenanthroline. It was tested positive for elastase activity towards elastin-orcein, thus appears to be an elastase, which is known as pseudolysin in other strains of P. aeruginosa. The protease withstands range of detergents, surfactants and solvents. It is stable and active in all the solvents having log P above 3.2, at least up to 72 h. These two properties make it an ideal choice for applications in detergent formulations and enzymatic peptide synthesis. 相似文献
146.
Ronald E. Banks Ismail M. Farhat Roy Fields Robin G. Pritchard Mohamad M. Saleh 《Journal of fluorine chemistry》1985,28(3):325-340
The nitrosoarenes ArNO (Ar = C6H5, 2-MeC6H4, 2,4,6- Me3C6H2 and C6F5) have been condensed with 4-(dichloroamino)- tetrafluoropyridine to provide the azoxy-compounds pyFN()Ar (pyF = 2,3,5,6-tetrafluoro-4-pyridyl); de-oxygenation of the first three with triphenylphosphine or triethyl phosphite gave the corresponding azo-compounds, and the reverse reaction was achieved in the case of pyFNNC6H2Me3-2,4,6 using peroxytrifluoroacetic acid. Thermolysis of 4-azidotetrafluoropyridine in the presence of pentafluoronitrosobenzene provided the perfluorinated azoxy-compound pyFN()C6F5. X-Ray methods have been used to determine the molecular geometry of pyFN()C6H2Me3-2,4,6. 相似文献
147.
Carl Bender Fred Cooper L. M. Simmons Jr. Pinaki Roy Greg Kilcup 《Journal of statistical physics》1991,64(1-2):395-428
We discuss the randomly driven systemdx/dt= -W(x) +f(t), wheref(t) is a Gaussian random function or stirring force withf(t)f(t)=2(t–t), andW(x) is of the formgx
1+2. The parameter is a measure of the nonlinearity of the equation. We show how to obtain the correlation functionsx(t)f(t)···x(t(
n))
f
as a power series in. We obtain three terms in the expansion and show how to use Padé approximants to analytically continue the answer in the variable. By using scaling relations, we show how to get a uniform approximation to the equal-time correlation functions valid for allg and. 相似文献
148.
Roy Aleksan Isard Dunietz Boris Kayser 《Zeitschrift fur Physik C Particles and Fields》1992,54(4):653-659
The weak phase γ is conventionally probed by theB s→ρ 0 mode. The predicted rate is tiny. Even if aB s→ρ 0 K s rate difference could be established, it would not be clear that sin 2γ had been measured, because amplitudes with other weak phases may contribute significantly. Non-CP eigenstates, such asB s →D s ± K ?, have a two-fold advantage overB s→ρ 0 K s. Their rates are orders of magnitude above that forB s→ρ 0 K s, and they probe theCP-violating phase γ, without any contamination from other weak phases. Detailed time-dependent studies of non-CP eigenstates remove possible final-state phases and extract the weak phase γ. 相似文献
149.