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1.
P. V. Verdes M. M. Mato J. L. Legido E. Jiménez M. I. Paz Andrade 《Journal of Thermal Analysis and Calorimetry》2007,88(2):613-616
Excess molar enthalpies
of the ternary system {x
1
p-xylene+x
2decane+(1–x
1–x
2)diethyl
carbonate} and the involved binary mixtures {p-xylene+(1–x)decane}, {xp-xylene+(1–x)diethyl carbonate} and {xdecane+(1–x)diethyl carbonate} have been determined at the
temperature of 298.15 K and atmospheric pressure, over the whole composition
range, using a Calvet microcalorimeter. The experimental excess molar enthalpies H
m
E
are positive for all the binary systems studied over the whole composition
range. Excess molar enthalpy for the ternary system is positive as well, showing
maximum values at x
1=0, x
2=0.4920, x
3=0.5080, H
m,123
E=1524
J mol–1. 相似文献
2.
P. V. Verdes M. M. Mato J. L. Legido E. Jiménez M. I. Paz Andrade 《Journal of Thermal Analysis and Calorimetry》2007,88(2):583-586
Excess molar enthalpies, H
E,
for the binary mixtures {p-xylene+(1–x) octane}, {x
p-xylene+(1–x)
diethyl carbonate}, {x octane+(1–x) diethyl carbonate} and the corresponding ternary
system {x
1
p-xylene+x
2
octane+(1–x
1–x
2) diethyl carbonate} have
been measured by using a Calvet microcalorimeter at 298.15 K under atmospheric
pressure. The experimental H
E
values are all positive for the binary and ternary mixtures over the entire
composition range. 相似文献
3.
T. Kimura Y. Takahashi T. Kamiyama M. Fujisawa 《Journal of Thermal Analysis and Calorimetry》2007,88(2):587-595
Excess enthalpies (H
E)
of 17 binary mixtures of o- and m-isomers of dichlorobenzene, difluorobenzene, methoxymethylbenzene,
dimethylbenzene, dimethoxybenzene, aminofluorobenzene, fluoronitrobenzene,
diethylbenzene, chlorofluorobenzene, fluoroiodobenzene, bromofluorobenzene,
chloromethylbenzene, fluoromethylbenzene, bromomethylbenzene, iodomethylbenzene,
fluoromethoxybenzene, dibromobenzene at 298.15 K were measured. All excess
enthalpies measured were very small, and those of o-+m-isomers of aminofluorobenzene, dibromobenzene and
iodomethylbenzene were negative but 14 other binary mixtures of isomers were
positive over the whole range of mole fractions. H
E
of o-+m-isomers
of dimethoxybenzene showed the largest enthalpic instability and those of
aminofluorobenzene showed the largest enthalpic stability. There was a correlation
between dipole–dipole interaction, dipole–induced dipole interaction
or entropies of vaporization and excess partial molar enthalpies at infinite
dilution. 相似文献
4.
G. A. Bagirzade 《Russian Journal of General Chemistry》2010,80(8):1672-1676
Kinetic laws of 4-bromo-phthalonitrile synthesis by vapor-phase oxidative ammonolisis of 4-bromo-o-xylene in the range of 633–69 K were studied. It was shown that formation of 4-bromophthalonitrile proceeds successively
through 4-bromo-o-tolunitrile. Conversion rates of 4-bromo-o-xylene and 4-bromo-o-toluinitrile were found to be described by half-order equations on the corresponding components and not to depend on the
oxygen and ammonia concentrations. 相似文献
5.
Yu. A. Borisov 《Russian Chemical Bulletin》2000,49(11):1820-1822
The proton affinity (PA) energies of fluoro derivatives of benzene, toluene, andm-xylene were obtained fromab initio MP2-FC/6-31G* calculations and compared with experimental results. Protonated forms of the molecules, resulting from different ways of
proton addition, were studied. Relative concentrations of isomeric arenonium ions were calculated and compared with the results
of NMR studies on arenonium ions in solutions.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1847–1849, November, 2000. 相似文献
6.
Rolf W. Berg 《Monatshefte für Chemie / Chemical Monthly》2007,138(11):1045-1075
Summary. A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate
picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical
results combined with vibrational spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT-Raman spectroscopic results on the model ionic liquid system of 1-butyl-3-methylimidazolium ([C4
mim][X]) salts. The rotational isomerism of the [C4
mim]+ cation is described: the presence of anti and gauche conformers that has been elucidated in remarkable papers by Hamaguchi et al. Such presence of a conformational equilibrium seems to be a general feature of the room temperature liquids. Then the “localized
structure features” that apparently exist in ionic liquids are described. It is hoped that the structural resolving power
of Raman spectroscopy will be appreciated by the reader. It is of remarkable use on crystals of known different conformations and
on the corresponding liquids, especially in combination with modern quantum mechanics calculations. It is hoped that these
interdisciplinary methods will be applied to many more systems in the future. A few examples will be discussed. 相似文献
7.
Mohan T. Hosamani Narasimha H. Ayachit D. K. Deshpande 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1301-1306
Thermodynamic parameters, like, change of activation energy for dipole orientation (ΔG*), enthalpy (ΔH*), and entropy (ΔS*) of activation in the case of binary-, ternary-, etc. mixtures of polar molecules in pure liquid phase or in dilute solution
phase in a non polar solvent helps in drawing certain quantitative conclusions regarding their relaxation behavior as to whether
a single component is responsible for observed microwave absorption or a cooperative phenomenon (average) by all the dipoles
of the mixture contribute to it. Dielectric relaxation behavior of polar molecules in a non-polar solvent, or mixtures of
these substances at different microwave frequencies and over a range of temperatures and concentrations give a method of determining
these quantities. Such an experimental investigation on verity of systems is necessary to draw quantitative conclusions regarding
the system of the molecules which are not studied so as to examine if the results obtained are in favor or against the general
conclusions already arrived at, in other systems. With this in view, systematic dielectric measurements in a range of temperatures
are carried out at a single microwave frequency on a single weight fraction in benzene of the four substituted indoles, namely,
5-Bromoindole, 5-Fluoroindole, 2,3-Dimethylindole, 2,5-Dimethylindole and on binary (1:1) mixtures of 2,5-Dimethylindole +
5-Bromoindole and 2,3-Dimethylindole + 5-Fluoroindole in benzene as solvent at different temperatures. The results are presented
and discussed. 相似文献
8.
K. N. Semenov N. A. Charykov V. A. Keskinov A. K. Pyartman V. V. Yakovlev O. V. Arapov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(11):1935-1939
The polythermal (over the temperature range 20–80°C) solubility of fullerene bromo derivatives C60Brn (n = 6, 8, 24) in several solvents (o-xylene, o-dichlorobenzene, n-decanol-1, and enanthic acid) was studied. The corresponding solubility polytherms are given. 相似文献
9.
Anita Kovács I. Csóka Magdolna Kónya E. Csányi A. Fehér I. Erős 《Journal of Thermal Analysis and Calorimetry》2005,82(2):491-497
Summary The properties of the inner and the external aqueous phases, were studied in w/o/w multiple emulsions with light microscopic image analysis and differential scanning calorimetry (DSC). The importance of multiple
emulsions lies in the presence of these aqueous phases, making them available for sustained, controlled drug delivery systems.
Differentiation of these two aqueous phases, studying the effect of manufacturing technology on droplet structure, quantitative
determination of phase volumes and any changes occurring during storage are essential when planning w/o/w emulsions. The present study uses microscopic observations combined with DSC measurements in order to identify the formed
structure, at developmental stage in case of different components, preparation methods, and stirring rates. These tools are
beneficial during manufacturing as in process controls, or to ensure product quality. 相似文献
10.
V. V. Islamova N. A. Kucher V. I. Poltavtsev 《Russian Journal of Applied Chemistry》2009,82(8):1408-1412
We obtained an analytical solution of a problem of unsteady mass transfer under the equilibrium condition y = Ax + B to compare results with a problem solution in the case of equilibrium condition looking as y = Ax. 相似文献
11.
I. A. Novakov V. V. Korolkov A. I. Pavlyuchko B. S. Orlinson L. A. Gribov 《Journal of Structural Chemistry》2004,45(4):563-569
An ab initio (6-31G**) study of binary associates of aniline and n-propylamine with nitrobenzene and m-cresol has been carried out. The structures corresponding to the total energy minimum of the system have been found for the associates, and their geometrical and energy characteristics have been determined. Basic types of intermolecular interactions have been established, and their effects on the reactivity of the amino group have been investigated.Original Russian Text Copyright © 2004 by I. A. Novakov, V. V. Korolkov, A. I. Pavlyuchko, B. S. Orlinson, and L. A. GribovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 595–601, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
12.
T. E. Vittal Prasad A. Phanibhushan D. H. L. Prasad 《Journal of solution chemistry》2005,34(11):1263-1272
Densities and viscosities of the binary mixtures of m-cresol with 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane and tetrachloroethylene were measured at
303.15, 313.15 and 323.15 K. The measured results are used to compute the excess volumes (VE), deviations in viscosity (Δη) and excess Gibbs energy for activation of flow (ΔGE). The excess volumes, deviations in viscosity, and Gibbs energies for activation of flow are fitted to a polynomial-type
equation suggested by Scharlin et al. [J. Chem. Thermodyn. 34, 927 (2002)] and are discussed in general terms. 相似文献
13.
Hongli Liu Satoko Kido Tadashi Kamiyama Masao Fujisawa Takayoshi Kimura 《Journal of Thermal Analysis and Calorimetry》2010,102(3):1123-1133
To obtain further systematic information for the isomer systems, the excess molar enthalpies for binary (o + m), (o + p), (m + p)-isomers of methoxymethylbenzene, ethylmethylbenzene, diethylbenzene, chloromethylbenzene, tolunitrile and fluorobenzonitrile,
tolylacetonitrile were measured at 298.15 K. In this article, the results are discussed and compared with those of previous
works. The excess enthalpies of binary systems in different solid and liquid states were measured when the pure component
of o-/m-tolunitrile, fluorobenzonitrile was titrated into the prior (o + p) or (m + p) mixtures. A series calculation for the interaction energies (IE) between the isomers was carried out for the pair molecules by ab initio MO of Gaussian 09. Correlations between the excess
enthalpies at a molar fraction of x = 0.5 and the intermolecular energy are discussed. 相似文献
14.
V. A. Drebushchak Yulia A. Kovalevskaya I. E. Paukov Elena V. Boldyreva 《Journal of Thermal Analysis and Calorimetry》2007,89(2):649-654
Heat capacity of D- and DL-serine was measured using adiabatic calorimetry in a temperature range of 5.5 to 300 K, and then thermodynamic functions
were calculated. The difference in heat capacity (C
PD-C
PDL) between two species indicates a small anomaly in D-serine near 15 K and a systematic excess over DL for temperatures > 30 K. This is much larger, than a difference in thermodynamic functions measured so far for the polymorphs
of organic molecular crystals. The excess is fitted well to Einstein contribution with characteristic temperature of 185 K
which is equivalent to vibrational mode at 129 cm−1. 相似文献
15.
Yong Li 《Theoretical chemistry accounts》2007,117(1):163-165
We present the theoretical results for the positions and widths of the initial anticrossing between Stark manifold n and n + 1 in sodium, obtained by using the method of diagonalization in which zero-field wave functions are chosen from a kind of atomic potential model. These results can provide the quantitative information for understanding the microwave ionization process, whose rate-limiting step is probably the n to n + 1 transition performed at the first crossing between the outermost states of these two manifolds. 相似文献
16.
Summary As a continuation of our studies on excess functions of binary systems containing acetonitrile-amines mixtures, in this work excess molar enthalpy (HmE) of acetonitrile+diethylamine or s-butylamine mixtures have been determined as a function of composition at 288.15, 293.15, 298.15 and 303.15 K at atmospheric pressure using a modified 1455 Parr adiabatic calorimeter. The excess enthalpy data are positive for both systems over the whole composition range. ERAS-Model calculations allowing for self-association and cross-association of the components were performed. The results of the calculations and the influence of temperature and isomers chains on the excess enthalpy behavior are discussed. 相似文献
17.
Catalytic and physicochemical properties of high-silica zeolites modified by multiple charge cations (Zn, Cd, Ba, La, Lu)
in the conversion of methanol to n-xylene were studied. 相似文献
18.
M. G. Voronkov N. N. Vlasova O. Yu. Grigor’eva Yu. N. Pozhidaev S. A. Bol’shakova 《Russian Journal of General Chemistry》2005,75(7):1091-1093
Condensation of (aminomethyl)triethoxysilane with thiocarbamide in the presence of catalytic amounts of ammonium sulfate was used to synthesize N,N-bis(triethoxysilylmethyl)thiocarbamide. The latter was brought into oxidative hydrolytic polycondensation with H2O2 to obtain poly[N,N′-bis(silsesquioxanylmethyl)thiocarbamide S, S-dioxide] whose properties were compared with the properties of poly[N,N′-bis(silsesquioxanylpropyl)thiocarbamide S,S-dioxide]. Both polymers in highly acidic media rather strongly absorb Ag(I), while at pH 7 they reduce most absorbed Ag+ to the metal. Their reaction with potassium permanganate involves reduction of Mn7+ to Mn4+. The first polymer is a less effective sorbent and redox agent than the second.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1154–1156.Original Russian Text Copyright © 2005 by Voronkov, Vlasova, Grigor’eva, Pozhidaev, Bol’shakova. 相似文献
19.
Yu. G. Voloshina L. K. Patrilyak V. V. Ivanenko K. I. Patrilyak 《Theoretical and Experimental Chemistry》2009,45(4):263-266
We propose a bimolecular mechanism for disproportionation of toluene to form benzene and para-xylene via protonation of the toluene molecule at the methyl group, reaction of the carbocation formed with the para position of the next toluene molecule, and α-scission of the complex obtained. The mechanism presumes formation of methyl
diphenyl methane as a byproduct of disproportionation. 相似文献
20.
A differential scanning
calorimeter (DSC) was used to determine binary solid-liquid equilibria (SLE)
for dibenzofuran+n-C24 and naphthalene+n-C24 mixtures. Results obtained with this technique
were compared with those predicted by two modified UNIFAC (Universal Functional
group Acitivity Coefficients) versions. This model is employed with the idea
to extensively investigate the validity of UNIFAC (Larsen and Gmehling versions).
The corresponding activity coefficients were calculated and applied to the
prediction of non-electrolyte mixtures real behavior. Reasons of prediction
without success in the case of using original interaction parameters, were
analysed and discussed. Interesting representation of solubility diagrams
was obtained using partly readjusted UNIFAC interaction parameters. The two
systems selected can be used for contributing to develop the data base using
group contribution methods. For practical purposes, SLE are of interest in
chemical process design, especially when process conditions must be specified
to prevent precipitation of a solid. 相似文献