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11.
12.
A general algorithm allowing the numerical modeling of the time and space dependence of product formation in spherical reaction volumes is described. The algorithm is described by the complete set of mass balance equations. On the basis of these equations, the effects of the diffusion coefficient, reaction rate, bead size, reagent excess, and packing density of the resin beads on the overall reaction rates are determined for second-order reactions. Experimental data of reaction progress are employed to calculate reaction rates and diffusion coefficients in polymer-supported reactions. In addition, the conditions for shell-like product formation are determined, and various strategies for the radial patterning of resin beads are compared. The effect of diffusion on polymer-supported enzyme-catalyzed reactions of the Michaelis-Menten type is treated, as well. Finally, the effects of typical nonideal solid-phase phenomena, namely, the inhomogeneity of rate constants and the concentration dependence of diffusion coefficients, on overall rates are discussed. 相似文献
13.
Ko C Levine B Toniolo A Manohar L Olsen S Werner HJ Martínez TJ 《Journal of the American Chemical Society》2003,125(42):12710-12711
The photoisomerization mechanism of the neutral form of the photoactive yellow protein (PYP) chromophore is investigated using ab initio quantum chemistry and first-principles nonadiabatic molecular dynamics (ab initio multiple spawning or AIMS). We identify the nature of the two lowest-lying excited states, characterize the short-time behavior of molecules excited directly to S2, and explain the origin of the experimentally observed wavelength-dependent photoisomerization quantum yield. 相似文献
14.
For the determination of flouride, chloride and bromide, a suitable metal ion is added in a modified graphite tube atomizer. After drying and ashing, the substances are vaporized and diatomic molecules between the metal and nonmetal are formed. These molecules are excited by a pulsed dye laser and the resulting fluorescence is measured. At constant metal concentration, the fluorescence is proportional to the halide concentration. The diatomic molecules used are MgF, InCl and AlBr. The detection limits are 11 pg of fluoride, 15 pg of chloride and 70 pg of bromide in the 10-μl injections, corresponding to 6 x 10?8 mol l?1 fluoride, 4 x 10?8 mol l?1 chloride and 9 x 10?8 mol l?1 bromides. 相似文献
15.
Winfried Mientus Hans-Georg Bartel Werner Haberditzl Hans-Joachim Spitzer 《Monatshefte für Chemie / Chemical Monthly》1980,111(3):597-606
A normalization of the wave functions by means of the theoretical exact Multiple-Scattering-(MS)-formalism is discussed within the framework of the SCF-X-SW-method. For the atomic and extramolecular regions the integrals of normalization can be easily determined and the results can be described by the corresponding electronic charges. The calculation of the integral of the interatomic region is problematic. The needful volume integration is only necessary to theGreen's functions of the wave functions and can be solved by means of the residual theory. The further analytical calculation of the surface integrals leads to a complicated formalism which can be numerically evaluated. 相似文献
16.
17.
Hans-Joachim Petzsche 《manuscripta mathematica》1978,24(2):133-171
This article is concerned with ultradistribution spaces in the sense of Komatsu. For these spaces several tensor product theorems, especially Schwartz's kernels theorem for ultradistributions, are proved. Criteria which ensure that a nuclear locally convex space has an absolute basis are given and used to represent the spaces of periodic ultradifferential functions as Köthe sequence spaces. These results permit to state conditions on a sequence {Mp} which are equivalent to nuclearity, s-nuclearity or-as will be shown in part II-even -nuclearity of the corresponding ultradistribution spaces. Under some natural conditions the Beurling ultradistribution spaces defined by Komatsu are shown to constitute a proper subclass of those introduced by Beurling. 相似文献
18.
Hans-Joachim Schulz Jürgen Liebscher Peter Luger Minxie Quian Johann Mulzer 《Journal of heterocyclic chemistry》1992,29(5):1125-1132
2,4,6-Trialkyl-1,3,5-triazines 1 can selectively be mono, bis or trisiminoformylated by reaction with trismorpholinomethane 2 or chloromethylene iminium salts 3 (Vilsmeier reagents), with each alkyl substituent reacting with only one molecule of the electrophile. The resulting aminoalkenyltriazines 4, 5 and 6 are partially or fully hydrolysed to corresponding formylation products. The latter exist either in enol or in unusual acylenamine tautomeric structures 10, 12 , and 13 , depending on the number of enamine or enol units found in the molecule. Reaction of triazines 1 with chlorobenzylidene iminium salts 16 gives monoiminobenzoylation to enaminotriazines 17 . 相似文献
19.
The oxidative cyclization of 5-(2-amino-5-methoxycarbonylphenyl)-substituted tricarbonyl[η4-cyclohexa-1,3-diene]iron complexes by air in protic medium provides the corresponding tricarbonyl[η4-4a,9a-dihydro-9H-carbazole]iron complexes. This procedure is applied to the total synthesis of the 3-methoxycarbonylcarbazole alkaloids mukonine and mukonidine. 相似文献
20.
Heller B Sundermann B Buschmann H Drexler HJ You J Holzgrabe U Heller E Oehme G 《The Journal of organic chemistry》2002,67(13):4414-4422
The photocatalyzed [2 + 2 + 2]-cycloaddition of nitriles with 2 equiv of acetylene to 2-pyridines can be carried out under mild conditions and represents a valuable extension to common synthetical methods. For the ideal wavelength range (350-500 nm), lamps as well as sunlight can be used. Working at room temperature and in organic solvents such as toluene or hexane as well as in water gives satisfying results in many cases. However, it is also possible to vary the solvent and the reaction temperature of the photocatalyzed synthesis and to choose, with respect to the specific substrate, specific requirements for this particular reaction and general requirements of the method. This simple and selective method derives its potential mainly from the large variety of applicable nitriles. Suitable substrates include (functionalized) aliphatic and aromatic nitriles as well as cyanamides derived from secondary amines. 相似文献