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1.
Summary A new method is elaborated for the synthesis of -chloronitroalkanes; it consists in the reaction of phosphorus pentachloride with acetals obtained by the addition of primary -nitro alcohols to vinyl alkyl ethers. 相似文献
2.
Xuemin Chen John L. Oscarson Sue E. Gillespie Hongjie Cao Reed M. Izatt 《Journal of solution chemistry》1994,23(7):747-768
The enthalpy changes at zero ionic strength (H°) for the ionization of water (H2O=H++OH–) were determined by flow calorimetry from the heats of mixing of aqueous NaOH and HCl solutions in the temperature range 250 to 350°C. Pitzer ion-interaction models developed by other workers were used to calculate enthalpies of dilution of aqueous NaOH, HCl, and NaCl solutions for the extrapolation of H values from the conditions of the experiment to infinite dilution. Equations are derived for thermodynamic quantities (log K, H°, S°, C
p
°
and V°) for the ionization of water using the H° values determined in this study from 250 to 350°C and literature log K and H° values from 0 to 225°C. Smoothed values of log K, H°, S°, C
p
°
, and V° are presented at rounded temperatures from 0 to 350°C and at the saturation pressure of water for each temperature. The equations in the present study provide a better representation of experimental thermodynamic data from 0 to 350°C than the Marshall-Franck equation. 相似文献
3.
《Chemical physics》1986,107(1):47-60
The results of a new neutron diffraction experiment to measure the structure of water are presented. The data, measured at the McMaster Nuclear Reactor, are of a high quality and are analysed to yield the hydrogen-hydrogen pair correlation function using a subtraction procedure which has been used in previous experiments of this kind. This procedure circumvents the necessity of applying inelasticity corrections. The results are in good agreement with earlier work and serve to establish the general correctness of the subtraction procedure when used to determine hydrogen correlations. The data are further analysed to yield separate oxygen-hydrogen and oxygen-oxygen partial structure factors for liquid water. For the second part of the analysis an effective mass model of the dynamic scattering law is used, with the model parameter, the effective mass of the scattering particle, chosen by a least-squares fit to the measured differential cross sections. The final pair correlation functions are obtained using a maximum entropy analysis of the structure functions. 相似文献
4.
5.
Takayoshi FujiiShinsuke Asai Tomoyuki OkadaWei Hao Hiroyuki MoritaToshiaki Yoshimura 《Tetrahedron letters》2003,44(33):6203-6205
Several diaryl(fluoro)-λ6-sulfanenitriles 3 were synthesized by the reaction of S,S-diarylsulfimides 1 with Selectfluor™. This reaction also allows the first preparation of heterocyclic fluoro-λ6-sulfanenitrile, 5-fluoro-10,10-dioxo-5,10-dihydro-5λ6,10λ6-thianthren-5-nitrile (5) and its molecular structure was determined by X-ray crystallographic analysis. 相似文献
6.
Yolanda A. Sanmamed Ana Dopazo-Paz Diego González-Salgado Jacobo Troncoso Luis Romaní 《The Journal of chemical thermodynamics》2009,41(9):1060-1068
A calibration procedure of vibrating tube densimeters for density measurement of liquids in the intervals (700 to 1600) kg · m?3, (283.15 to 323.15) K, and (0.1 to 60) MPa is presented. It is based on the modelization of the vibrating tube as a thick-tube clamped at one end (cantilever) whose stress and thermal behaviour follows the ideas proposed in the Forced Path Mechanical Calibration model (FPMC). Model parameters are determined using two calibration fluids with densities certified at atmospheric pressure (dodecane and tetracholoroethylene) and a third one with densities known as a function of pressure (water). It is applied to the Anton Paar 512P densimeter, obtaining density measurements with an expanded uncertainty less than 0.2 kg · m?3 in the working intervals. This accuracy comes from the combination of several factors: densimeter behaves linearly in the working density interval, densities of both calibration fluids cover that interval and they have a very low uncertainty, and the mechanical behaviour of the tube is well characterized by the considered model. The main application of this method is the precise measurement of high density fluids for which most of the calibration procedures are inaccurate. 相似文献
7.
The reaction of the Na2MoO4 or Na2WO4 salt with organic amine and PCl5, SiCl4 or TiCl4 in hydrochloric acid medium under hydrothermal conditions yields organic–polyoxometallate hybrid compounds, with the following reaction formula: Na2MO4 + Lewis-base + XCln + HCl → (Lewis-baseH)m(XM12O40) + NaCl + H2O (M = Mo or W; X = P, Si, Ti,; n = 3–5). By using this method, four new complexes, [(CH3)2NH]3[H3PW12O40] (1), (C2H5OH)3(H3PMo12O40) (2), [DMDA]2[H4SiW12O40]·H2O (3) (DMDA = 1 N,3 N-dimethyl-1,3-diazolidine) and [(DAN)6][H4TiW12O40]·4H2O (DAN = 4,4′-dianiline) (4), were obtained, and their crystal structures are reported. Thermal analysis of 1, 2 and 4 has been carried out. The thermal analysis indicates that the Keggin anion skeleton begins to decompose at about 300 °C. The possibility of constructing hydrogen-bond interactions by association between the polyoxometallate and the organic compound is explored. The roles of solvents and organic groups in the formation of specific crystalline architectures are discussed. The crystal structure of [H4TiW12O40], a hetero-transition-metal Keggin polyoxometallate with a square-plane TiO4, has been reported. Four architectures developed by hydrogen-bond associations of different Keggin polyoxometallates and organic bearing N–H or O–H donor functions are described. The selected organic modules (4,4′-dianiline, 1,3-dimethylimidazolidine, dimethylamine and ethanol) possess hydrogen-donor functions to allow them to act as bridges between polyoxometallate groups. Depending on the nature of the donor group, the number of hydrogens available for bonding, the geometric features and the sizes of the organic modules, diverse assembling patterns have been observed ranging from one-dimensional to three-dimensional networks. For all the networks, H3O+ and H+ act as actual linkers between the molecular units. 相似文献
8.
《Electrochemistry communications》1999,1(9):415-418
A new method has been developed to analyze current–potential curves. The treatment was applied to determine the kinetic parameters of oxygen reduction. The reduction of oxygen was studied on thin-film platinum electrodes in alkaline solution. For the purpose of comparison the kinetic parameters were determined by the traditional method of constructing Tafel plots. 相似文献
9.
《The Journal of chemical thermodynamics》2002,34(3):303-317
A flow mixing calorimeter, followed by a vibrating tube densimeter, has been used to measure excess molar enthalpies HmEand excess molar volumesVmE of {xCO2 + (1 − x)SF6}. Measurements over a range of mole fraction x have been made at the temperatures T = 302.15 K and T = 305.65 K at the pressures (3.76, 5.20, 6.20, and 7.38) MPa. The lowest pressure 3.76 MPa is close to thecritical pressure of SF6 and the highest pressure 7.38 MPa is close to the critical pressure of CO 2. Measurements atx = 0.5 have been made over the pressure range (2.5 to 10.0) MPa at the temperature 301.95 K. Some of the measurements are very close to the critical locus of the mixture. The measurements are compared with the Patel–Teja equation of state which reproduces the main features of the excess function curves as well as it does for similar measurements on {xCO2 + (1 − x)C2H6} and{xCO2 + (1 − x)C2H4} . The equation was used to calculate residual enthalpies and residual volumes for the pure components and for the mixture, and inspection of the way these combine to give excess enthalpies and volumes assisted the interpretation of the pressure scan measurements. 相似文献
10.
Diffusion-kinetic calculations [1-3] have been analysed to determine the isotopic effect in the radiolysis of water with ionising radiation of linear energy transfer characteristics (LET) from 0.2 to 60 eV/nm and at temperatures up to 300°C. This analysis shows that, for low LET radiation, the spur decay of e- aq is slower in D2O and results in a higher yield of e- aq, g(e- aq), at 10-7 -10-6s after the ionisation event. In low LET radiolysis, g(OD) ≈ g(OH) over the whole range of temperature but in high LET radiolysis g(OD) is clearly lower than g(OH). The isotopic effect on the yields of the radical products is enhanced by increasing LET but diminished by increasing temperature. The yields of the molecular products show the opposite isotopic effect to their radical precursors, namely g(D2) is 10-20% lower than g(H2) and g(D2O2) > g(H2O2). A particularly significant difference between g(D2O2) and g(H2O2) has been found at LET = 20 eV/nm. The isotopic dependence of the g-values estimated for fast neutron radiolysis is also presented. 相似文献
11.
A. Konguetsof 《Journal of mathematical chemistry》2010,47(2):871-890
With this paper, a new algorithm is developed for the numerical solution of the one-dimensional Schrödinger equation. The new method uses the minimum order of the phase-lag and its derivatives. Error analysis and the numerical results illustrate the efficiency of the new algorithm. 相似文献
12.
Xiao Zhen Liu Fei Wang Dong Dong Luo Xing Guo Guang Qing Lei 《中国化学快报》2007,18(11):1339-1341
The hydroxyl group of carbocyclic nucleosides was inversed when the compounds were treated with Me_3SiCl,KCN and a catalytic amount of NaI in DMF/CH_3CN. 相似文献
13.
Comprehensive (p, ρ, T) measurements on cyclohexane, toluene, and ethanol were carried out in the homogeneous liquid phase for temperatures from 233.15 K to 473.15 K at pressures up to 30 MPa. The measurements were performed by using an accurate single-sinker densimeter based on the Archimedes’ buoyancy principle. The total uncertainty of the measurements in density was estimated to be 0.015% (level of confidence 95%). Based on the experimental results, accurate correlation equations for the density of the three liquids have been established; their uncertainty is 0.020%. Comparisons with previous results of other experimentalists and with values calculated from current equations of state are presented. In this context it is also shown that the density of a liquid can vary slightly depending on the batch of the liquid used for the measurements. The purpose of this work was to provide accurate correlation equations for the densities of the three selected liquids so that these liquids can be used as density reference liquids for the calibration of densimeters and, in particular, for the calibration of vibrating-tube densimeters. 相似文献
14.
《Supramolecular Science》1998,5(5-6):469-473
The Fenton reactions occur because of the generation of H2O2 in the photoexcited independent TiO2 systems or TiO2/SnO2 coupled systems. The ·OH radicals in these reactions were indirectly measured by colorimetric method. According to the Lambert–Beer law, we obtained the qualitative and quantitative relationships between the amount of TiO2 or TiO2/SnO2 coupled particles and the amount of ·OH radicals produced by these systems. It provides a convenient procedure for making a thorough study on the photocatalytic mechanism of semiconductor nanoparticles, and in particular, to select highly efficient multicomponent semiconductor systems for photocatalysis. 相似文献
15.
SHI Zhen WANG Luyao GU Huan LI Jianli BAI Yinjuan & YANG Bingqin Department of Chemistry Northwest University Xi''''an China 《中国科学B辑(英文版)》2005,48(Z1)
A facile and efficient method for the formylation of Grignard reagent was reported, and a new approach for the preparation of aldehydes from Grignard reagent and benzimida-zolium salts was provided. 相似文献
16.
Hao Hu Bei Yan Wei Zhang Wenbo Yan Liquan Liu Xiaofeng Tang Kejun Dong Longjie Li Xianjin Xiao Chengliang Xiong 《中国化学快报》2023,34(2):107418-342
Sperm damage caused by reactive oxygen species(ROS) is one of the main causes of male infertility.Therefore, the level of ROS in sperm is an important indicator for the diagnosis and prognosis of male infertility. Herein, we constructed a single sperm ROS detection method(SSRDM) with an optical microprobe fabricated via focused ion beam process. The micro-probe is used to separately excite fluorescence in the sperm and the area around the sperm after ROS staining, and the difference in fluoresce... 相似文献
17.
An efficient angular momentum method is presented and used to derive analytic expressions for the vibration-rotational kinetic energy operator of polyatomic molecules.The vibration-rotational kinetic energy operator is expressed in terms of the total angular momentum operator J,the angular momentum operator J and the momentum operator p conjugate to Z in the molecule-fixed frame Not only the method of derivation is simpler than that in the previous work,but also the expressions ot the kinetic energy operators arc more compact.Particularly,the operator is easily applied to different vibrational or rovibrational problems of the polyatomic molecules by variations of matrix elements Gn of a mass-dependent constant symmetric matrix 相似文献
18.
V. M. Tapilin 《Journal of Structural Chemistry》2017,58(1):1-8
A new method of solving the many-body Schrödinger equation is proposed. It is based on the use of constant particle-particle interaction potential surfaces (IPSs) and the representation of the many-body wave function in a configuration interaction form with coefficients depending on the total interaction potential. For these coefficients the corresponding set of linear ordinary differential equations is obtained. A hierarchy of approximations is developed for IPSs. The solution of a simple exactly solvable model and He-like ions proves that this method is more accurate than the conventional configuration interaction method and demonstrates a better convergence with increasing basis set. 相似文献
19.
YANG Bing-Hui JIANG Ji-Qing HUANG Xiao-Lin WU Hou-MingState Key Laboratory of Bio-organic Natural Products Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai China 《中国化学》1997,15(2):178-187
This reaction provided an efficient method to synthesize C-furanoside derivatives in high yields and stereospecificity under mild conditions.The cyclization mechanism regarding benzyl group as a leaving group was discussed and their stereochemistry was deduced by 1H-1H NOESY data. 相似文献
20.
Xing Hai Li Xin Ling Yang Xiao Mei Liang Zhen Peng Kai Yun Ling Fu Heng Chen Dao Quan Wang 《中国化学快报》2007,18(12):1476-1478
α-Chlorocycloalkanones(Ⅳ) were synthesized from cycloalkanones via potassiumα-oxocycloalkylsulfonates(Ⅱ).A two-step mechanism was proposed to explain the formation ofⅣfromⅡ. 相似文献