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151.
152.
N. N. Zemlyanskii I. V. Borisova A. K. Shestakova Yu. A. Ustynyuk E. A. Chernyshev 《Russian Chemical Bulletin》1998,47(3):469-474
The first stable dibenzosilafulvene, 9-{[8-(dimethylaminomethyl)-1-naphthyl]phenylsil-1-ylium}fluoren-9-ide (7a), was obtained in one step from 9-fluorenyllithium and chloro[8-(dimethylaminomethyl)-1-naphthyl]phenylsilane as a stable
solvate with THF. The structure of the zwitterionic compound7a was established by1H,13C, and29Si NMR in solution and in the solid state. The reactions of compound7a with crotonaldehyde, ethanol, and triethylethylidenephosphorane are described. The data on the synthesis of alkoxy- and alkylthiochloro-9-fluorenylsilanes
and their phosphonium salts are given.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 486–491, March, 1998. 相似文献
153.
Diffusion coefficients of copper sulfate-water and copper sulfate-sulfuric acid-water solutions have been determined at 25°C using conductimetric and diaphragm-cell techniques. The ternary diffusion measurements indicate that diffusion of sulfuric acid can produce large counterflows of copper sulfate and vice versa. If diffusion of copper sulfate in aqueous sulfuric acid solutions is treated as a binary process, the measured apparent diffusivities of copper sulfate can be 1 to 8% lower than the salt's true diffusivity. Equations are developed to predict transport coefficients from the concentrations and mobilities of the diffusing species. 相似文献
154.
M. Wei X. Y. Xu J. He G. Y. Rao H. L. Yang 《Journal of Thermal Analysis and Calorimetry》2006,85(3):795-800
Supramolecular 2,3- and 2,5-pyridinedicarboxylate (PDC) intercalated
ZnAl-layered double hydroxides (2,3- and 2,5-PDC–ZnAl–LDHs) have
been prepared by ion exchange method. The structure and composition of the
intercalated materials have been studied by X-ray diffraction (XRD) and inductively
coupled plasma emission spectroscopy (ICP). The study indicates that the 2,3-PDC
and 2,5-PDC anions are accommodated as interdigitated bilayer and monolayer
arrangement respectively between the sheets of LDHs. Furthermore, their thermal
decomposition processes were studied by the use of in situ high temperature
X-ray diffraction (HT-XRD), and the combined technique of thermogravimetry-differential
thermal analysis-mass spectrometry (TG-DTA-MS) under N2 atmosphere. Based
on the comparison study on the temperatures of both decarboxylation and complete
decomposition of interlayer PDC, it can be concluded that 2,5-PDC–ZnAl–LDHs
has higher thermal stability than that of 2,3-PDC–ZnAl–LDHs. 相似文献
155.
In the context of the density functional theory of the local electron density the valence and differential density distribution in crystalline sulfates of M2SO4 (M is Li, Rb, and Cs) and double sulfates of MLiSO4 were calculated using the pseudopotential method in the basis set of numerical atomic pseudo-orbitals. It is shown that in lithium sulfate crystallographically inequivalent oxygen atoms are in different charge states and have a different force of chemical bonding with sulfur. Anions are bonded to each other through lithium atoms that form tetrahedral complexes with oxygen. In rubidium sulfates the electron clouds of the anions overlap and chain structures form. Chemical bonding between the anion and the cation has an ionic nature. These features of the electron structure manifest themselves in double sulfates, where LiO4 complexes that link the anionic chains also form, and heavy metals serve as cations. 相似文献
156.
Xin-Rui Wang Hui-Min Cheng Xue-Wei Gao Wei Zhou Shu-Jing Li Xue-Li Cao Dongpeng Yan 《中国化学快报》2019,30(4):919-923
The inhibitor of melanin and the bacteriostatic agent kojic acid was inserted into Zn-Ti layered double hydroxide (LDH) by anion-exchange reaction. The structure, slow release, antibacterial and skin whitening activity were studied. 相似文献
157.
At 20–70 °C, the temperature has almost no effect on the semisaturation field,B
1/2, or on the magnetic effects detected by exciplex fluorescence (pyrene/N,N-dimethylaniline) in binary benzene-DMSO mixtures. In individual solvents (ethanol, methanol) heating leads to a noticeable
increase in the magnetic effect, whileB
1/2 decreases. The results obtained corroborate a previously proposed hypothesis that polar microclusters are formed in binary
solvents with components of different polarity.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1821–1823, October, 1993. 相似文献
158.
Densities,ρ, ultrasonic speeds, u, viscosities,η, and refractive indices, n, of pure benzene, benzyl alcohol (BA), benzonitrile (BN), benzoyl chloride (BC), chlorobenzene (CB) and their thirty six binary mixtures, with benzene as common component, were measured at 303.15 K over the entire mole fraction range. From these experimental data the values of deviations in ultrasonic speed, △u, isentropic compressibility, △ks,excess acoustic impedance, ZE, deviation in viscosity, Dh, and excess Gibbs free energy of activation of viscous flow, G*E, and partial molar isentropic compressibility, Kφ,20 of BA, BN, BC and CB in benzene were computed. The variation of these derived functions with composition of the mixtures suggested the increased cohesion
(molecular order) in the solution and that interaction (A-B)>(A-A) or (B-B).Moreover, theoretical prediction of ultrasonic speed, viscosity and refractive index of all the four binary mixtures was made on the basis of empirical and semi-empirical relations by using the experimental values of the pure components. Comparison of theoretical results with the experimental values was made in order to assess the suitability of these relations in reproducing the
experimental values of u, η and n. Also, molecular radii of pure liquids and the average molecular radii of binary mixtures were evaluated using the corresponding refractive indices of pure liquids and binary mixtures. The average molecular radii of binary mixtures were found to be additive with respect to mole fraction of the pure component. 相似文献
159.
Solid-state 2H NMR spectroscopy is a well-established and versatile method to study molecular orientation and dynamics in selectively deuterated samples. Herein, we introduce a 2D 2H double-quantum (DQ) NMR experiment performed under fast magic-angle spinning with a slight offset of the magic angle (OMAS). The experiment combines 2H chemical-shift resolution with DQ-filtered quasistatic 2H line shapes. In this way, it is possible to separate 2H resonances and to independently determine 2H quadrupole couplings at multiple sites. While 2H chemical shifts are resolved in the 2H DQ dimension, the quadrupole parameters can be obtained from characteristic line shapes which are reintroduced in the second dimension by the magic-angle offset. The 2D 2H DQ OMAS experiment is demonstrated on L-histidine which was deuterated at multiple sites by recrystallisation from D2O. 相似文献
160.
A method based on Pitzer's model has been used for calculation of the solubilities of carnallite type double salts crystallizing in the systems MeX–MgX2–H2O (Me=Li, NH4, K, Rb, Cs; X=Cl, Br). The solubility of congruently soluble double salts was also determined experimentally at 25–75°C. The results from studies of the solubility diagrams of ternary carnallite type water-salt systems over a wide temperature range are summarized. It is found that the width of the crystallization region for each of the salts can be explained by the relative differences in the solubilities of the ternary solution components (MeX, MgX2·6H2O and MeX·MgX2·6H2O) and by a change of temperature, and by the effect of temperature on the solubility. A method is proposed for calculating Pitzer's ternary parameters of interionic interaction (MN and MNX) on the basis of experimental data for the solubility in water of the double salts crystallizing in the corresponding ternary water-salt systems. 相似文献