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31.
32.
R. Haas I. Schreiber M. Losekam G. Koss 《Fresenius' Journal of Analytical Chemistry》1989,335(8):980-981
Summary Three methods (photometry, TLC, HPLC) are proposed for the separation, detection and determination of the cancerogenic compounds benzidine, - and -naphthylamine in drinking water. The necessary detection limit of 0.1 g/l has been achieved. 相似文献
33.
A supramolecular poly[3]pseudorotaxane was prepared by self-assembly of a homoditopic cylindrical bis(crown ether) host and a bisparaquat derivative in solution by host-guest complexation. 相似文献
34.
The availability for the first time of detailed rate constants k(V′, R′, T′) (where V′, R′ and T′ are product vibrational, rotational and translational excitation) for the highly exothermic reaction H + F2 → HF(V′, R′) + F has prompted the 3D classical-trajectory study reported here. The potential-energy surface is found to be predominantly repulsive (⊥ ≈ 42%, R⊥ ≈ 58%) corresponding to the rather low fractional conversion of reaction energy into vibration ((f′V) = 0.58 from experiment, and 0.56 from theory). In the homologous series of reactions H + X2 (X F, Cl, Br, I) the percentage of repulsive energy-release decreases for X Cl, Br, I, but increases from X F to Cl. It is shown that this cannot be due to charge in mass-combination, but can plausibly be explained by the anomolously short range of interaction between the separating X atoms in the case X F. It is predicted that the more-forward scattered HF will be more rotationally excited. The form of the cross section function Sr(T) (where T is reagent translation) is analysed. In accordance with the expectation for a strongly exothermic reaction, it is found that Sr(T) rises more steeply than Sr(V) (where V is reagent vibrational energy). The effect on the product energy distribution conforms qualitatively to the “adiabatic” behaviour noted in previous work: ΔT → ΔT′ + ΔR′; ΔV → ΔV′. The explanation is to be found in reaction through more-compressed or more-extended intermediate configurations than are characteristic of room temperature reaction. We note the existence of an amplification effect: (ΔT′ + ΔR′)/ΔT ≈ 2, and ΔV′/ΔV ≈ 2. 相似文献
35.
Two new synthetic approaches to the title compounds are reported. In the first of these, starting with N-carbobenzyloxysarcosine, four synthetic steps are employed to finally assemble the C3? C4 bond of the 1,2-benzothiazine ring. In the second approach, an enol ether is employed as a protecting group to allow formation of the 3-carboxamide function, which is followed by cleavage of the ether function to yield the desired 4-hydroxy-1,2-benzothiazine-3-carboxamide 1,1-dioxide. 相似文献
36.
Yasri A Berthelot D Gijsen H Thielemans T Marichal P Engels M Hoflack J 《Journal of chemical information and computer sciences》2004,44(6):2199-2206
REALISIS is a software system for reagent selection, library design, and profiling, developed to fit the workflow of bench chemists and medicinal chemists. Designed to be portable, the software offers a comprehensive graphical user interface and rapid, integrated functionalities required for reagent retrieval and filtering, product enumeration, and library profiling. REALISIS is component-based, consisting of four main modules: reagent searching; reagent filtering; library enumeration; and library profiling. Each module allows the chemist to access specific functionalities and diverse filtering and profiling mechanisms. By implementing the entire process of reagent selection, library design, and profiling and by integrating all the necessary functionalities for this process, REALISIS cuts the time required to design combinatorial and noncombinatorial libraries from several days to a few hours. 相似文献
37.
Photosynthesis is one of the fascinating fields of current interdisciplinary research. It seems miraculous that nature, in the process of evolution, has managed to bring about the process of photosynthesis. The first step involves a charge separation at the reaction centers, which proceeds with 100% quantum yield from the photoexcited singlet state of the bacteriochlorophyll donor, despite the fact that the wasteful deactivation of the electron into the ground state should be highly favored. Biomimetic model compounds (that is, those which resemble the pigments nature has developed) have been constructed from porphyrins and quinones. These model systems have allowed the study of the factors contributing to the highly efficient charge separation. This report focuses on recent developments in the study of electron transfer in porphyrinoquinones. Some of the results of these investigations may not be not fully understood and are often the subject of controversial discussions. 相似文献
38.
Anion excess colorless fluorite-type strontium-yttrium chloride has been prepared. Single crystals of the SrY compound exhibit a primitive cubic lattice with a = 6.967(1)Å. Two mutually exclusive structural models for solutions, neither of which is exact, are discussed. The first is a vacancy model in which the extra charge which results from substitution of Y3+ for Sr2+ is balanced by the simultaneous removal of a Sr2+Cl? ion pair. This model requires individual ion sites to be partially occupied and nonequivalent and is strongly suggestive of vacancy ordering. Refinement in space group P1, with sites refined independenty, led to R = 0.1096. The second model describes the structure in terms of a Willis cluster of defects and includes both anion vacancies and interstitial anions. Full-matrix least squares refinement in space group Fm3m, with positions analogous to those in UO2.12 and (Ca,Y)F2.10, converged at R = 0.0633 for the 114 face-centered parent structure reflections whose |F|;2 > σ(F2). This second model is discussed in relation to a probable true solution which involves longrange order. 相似文献
39.
Tallarico JA Depew KM Pelish HE Westwood NJ Lindsley CW Shair MD Schreiber SL Foley MA 《Journal of combinatorial chemistry》2001,3(3):312-318
The synthesis and use of an alkylsilyl-tethered large (500-600 microm) polystyrene resin (1) are disclosed. An optimized Suzuki coupling of bromine-functionalized polystyrene and a silicon-functionalized alkylborane generates the silicon-substituted polystyrene 1 in large scale (>100 g). Resin loading is accomplished by activation as the silyl triflate, which can accommodate even sterically encumbered secondary alcohols and phenols. Treatment with HF/pyridine for linker cleavage is mild, efficient, and amenable to an automated, large-scale distribution system. This platform delivers, minimally, 50 nmol of each small molecule derived from a diversity-oriented, split-pool synthesis on a per bead basis for use in both forward and reverse chemical genetic assays. This technology satisfies many requirements of a one bead-one stock solution approach to chemical genetics. 相似文献
40.
Harry W. Gibson Dennis K. Chesney Frank D. Popp 《Journal of heterocyclic chemistry》1972,9(3):541-544
Treatment of 2-(4-chlorobutanoyl)- and 2-(5-chloropentanoyl)-1, 2-dihydroisoquinaldonitrile with sodium hydride gave rise to tricyclic benzoquinolizone and azepino[1,2-α]isoquinoline derivatives. A similar reaction was observed in the quinoline series. Several reactions of 1,2,3,4-tetrahydro-4-oxo-11bH-benzo[α]quinolizine-11b-carbonitrile are reported. 相似文献