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1.
A. M. Nazarov 《High Energy Chemistry》2000,34(5):301-303
Chemiluminescence activated by the chelates Eu(tta)3phen and Eu(dbm)3phen in the thermal decomposition of diphenyldiazomethane in benzene in the presence of oxygen was examined at 333 K. The
following photophysical characteristics of the luminescence emitter, excited triplet benzophenone (BP), were found: the phosphorescence
quantum yield ϕ
BP
0
= 1.0 × 10−5, the true lifetime τ
BP
0
= 7 × 10−8 s, and the rate constant of radiative deactivationk
r, BP = ϕ
BP
0
τ
BP
0 −1
= 160 s−1. 相似文献
2.
Inverse gas chromatography has been used to evaluate the adsorption parameters (ΔHa, ΔHst, ΔSa and ΔGa) of some probe molecules, each representing a class of organic (n-hexane, cyclohexane, benzene, n-octane, 1-octene and isooctane) on bentonite and chemically treated-bentonites. The adsorption parameters of the probes on
the bentonite samples were determined in infinite dilution region. Adsorption of the organic species was investigated in the
temperature range of 200–275∘C, using a flame ionization detector, and nitrogen as a carrier gas. The net retention volumes (Vn) of the probes were determined by the help of the retention times (tR) observed on gas chromatograms for each probe. Injection was made at least three times for each probe, obtaining reproducible
results of ± 0.5%. It was found that benzene exhibits more negative ΔH than for n-hexane and cyclohexane on all of the adsorbents. In addition, it was found that 1-octene exhibits more negative ΔH than for n-octane and isooctane on the chemically treated-bentonites, whereas n-octane exhibits more negative ΔH than for 1-octene and isooctane on the natural bentonite. Also, interactions of benzene with the natural- and chemically
treated-bentonites were found to be stronger than those of n-hexane and cyclohexane with the same carbon number. Again, interactions of the 1-octene with the chemically treated-bentonites
were found to be stronger those of n-octane and isooctane with the same carbon number. On the contrary, interactions of n-octane with the untreated-bentonite were found to be stronger than those of 1-octene and isooctane. 相似文献
3.
The excess molar volumes, V
mE, viscosity deviations, Δη, and excess Gibbs energies of activation, ΔG
*E, of viscous flow have been investigated from density and viscosity measurements for two ternary mixtures, 1-butanol + triethylamine
+ cyclohexane and 1-pentanol + triethylamine + cyclohexane, and corresponding binaries at 303.15 K and atmospheric pressure
over the entire range of composition. The empirical equations due to Redlich-Kister, Kohler, Rastogi et al., Jacob-Fitzner,
Tsao-Smith, Lark et al., Heric-Brewer, and Singh et al. have been employed to correlate V
mE, Δη and ΔG
*E of the ternary mixtures with their corresponding binary parameters. The results are discussed in terms of the molecular interactions
between the components of the mixture. Further, the Extended Real Associated Solution, ERAS, model has been applied to V
mE for the present binary and ternary mixtures, and the results are compared with experimental data. 相似文献
4.
The cosolvent system poly(p-tert butylphenyl methacrylate) (3)/acetone(1)/cyclohexane (2) has been studied at 298 K by light scattering, refractive index increment of dialysis equilibrium and viscometry. The preferential adsorption coefficient, λ1, for the whole composition range of the binary mixture acetone (1)/cyclohexane(2) has been determined. The values have been compared with the theoretically calculated values. The results indicate that in this system it is necessary to take into account the tertiary interaction parameters χ123, χ122 and χ233. 相似文献
5.
M. N. Roy R. K. Das A. Bhattacharjee 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(13):2201-2210
Apparent molar volumes ϕν and viscosity B-coefficients for tetrabutyl ammonium bromide (TBAB) in (0.00, 0.05, 0.10, and 0.15) mol dm−3 aqueous ascorbic acid solutions have been determined from solution density and viscosity measurements at temperatures over
the range 298.15 to 318.15 K as function of concentration of ascorbic acid solutions. In the investigated temperature range,
the relation: ϕν0 = a
0 + a
1
T + a
2
T
2, have been used to describe the partial molar volume ϕν0. These results, in conjunction with the results obtained in pure water, have been used to calculate the standard volumes
of transfer Δϕ
ν
0 and viscosity B-coefficients of transfer for TBAB from water to aqueous ascorbic acid solutions for rationalizing various interactions in
the ternary solutions. The structure making or breaking ability of TBAB has been discussed in terms of the sign of (δ2ϕν0/δT
2)
P
. An increase in the transfer volume of TBAB with increasing ascorbic acid concentration has been explained by Friedman-Krishnan
co-sphere model. The activation parameters of viscous flow for the ternary solutions studied have also been calculated and
explained by the application of transition state theory. 相似文献
6.
V. P. Novikov S. A. Tarasenko S. Samdal L. V. Vilkov 《Journal of Structural Chemistry》2000,41(2):217-230
The geometrical parameters for 1,1-dimethylsilacyclobiitane and 1,1,3,3-tetramethyl-13-disilacyclobutune are detemiined by
gas phase electron diffraction analysis using a dynamic model, which considers ring inversion as a large-amplitude motion.
The structural and potential function parameters were refined with allowance for molecular geometry relaxation estimated by
quantum chemical calculations with an HF/6-311G** basis. The potential function of 1,1-dim ethylsilacyclobutane is represented
as V(ϕ) = V0[(ϕ/ϕe)2 − 1]2 with V0 = 1.3 ± 1.2 kcallmole and ϕe = 29.7±4.5°, where ϕ is the ring puckering angle. A more reliable estimate for the height of the barrier (V0 = 0.56 kcallmole) was obtained by solving the one-dimensional quantum vibrational problem and by fitting the frequency of
the 0 →2 transition to the experimental value. For 1,1,3,3-tetram ethyl-1,3-disilacyclobutane, the potential function is adequately
represented bx V(ϕ) = Aϕ2, where A = (4.9 ± 1.8) · 10−4 kcall(mole · deg2) with a minimum coiresponding to a planar ring conformation with ϕ = 0°. The calculated structural parameters are compared
with the data for related compounds.
Translated fromZhumal Struktumoi Khimii. Vol. 41, No. 2, pp. 269–284, March–April, 2000 相似文献
7.
Manapragada V. Rathnam Sharad Mankumare Kirti Jain M. S. S. Kumar 《Journal of solution chemistry》2012,41(3):475-490
Densities, viscosities and speeds of sound of binary mixtures of ethyl benzoate with cyclohexane, n-hexane, heptane and octane have been measured over the entire range of composition at (303.15, 308.15 and 313.15) K and at
atmospheric pressure. From these experimental values, excess molar volume (V
E), deviation in viscosity (Δη) and deviation in isentropic compressibility (ΔK
s) have been calculated. The viscosities of binary mixtures were calculated theoretically from the pure component data by using
various empirical and semi-empirical relations and the results compared with the experimental findings. 相似文献
8.
The absorption spectra of isoquinoline-iodine or 2,4-lutidine-iodine solutions in organic solventsn-hexane,n-heptane, cyclohexane, carbon tetrachloride, benzene, toluene, chlorobenzene, ando-dichlorobenzene have been measured and interpreted in terms of the D+I2=DI2 equilibrium, where D is isoquinoline or 2,4-lutidine. Values ofK (288–320°K), ΔHo, and ΔSo for the reaction were calculated. A correlation between theK values and the solubility parameter of the solvent (Buchowski's relation) has been found. 相似文献
9.
Abdul Shakoor Tasneem Zahra Rizvi Ahmad Nawaz Sangra 《Polymer Science Series A》2010,52(10):1034-1043
Polyaniline (PANI)-montmorillonite (MMT) nanocomposites were prepared by direct intercalation of aniline molecules into MMT
galleries, followed by in situ mechanochemical polymerization under solvent free conditions. X-rays diffraction, Fourier Transform
Infra Red analyses and UV-vis spectroscopy confirmed the successful synthesis of polyaniline chains between the MMT nano-interlayers.
On increasing the amount of MMT basal spacing decreased gradually, suggesting less intercalation with decreasing amount of
aniline. Scanning electron micrographs demonstrated strong differences between the morphologies of PANI-MMT nanocomposites
and those of pure MMT and PANI. DC conductivity was measured in the temperature range from 145 K to 303 K using four probe
methods. Temperature dependent DC conductivity of PANI and all the PANI-MMT composites followed 3 dimensional variable range
hopping (3D VRH) model. Frequency dependent AC conductivity (σAC), dielectric constant (ɛ′) and loss factor (ɛ″) have been measured in the frequency range 102–106. All these measured quantities; σAC, ɛ′ and ɛ″ decreased with the increase in MMT content in the composites at all frequencies. The frequency dependence of σAC displayed a low frequency region below 104 Hz with almost constant conductivity, while above this frequency a rapid rise in σAC was observed with a power law of frequency dependence with an exponent equal to 0.7. Both real and imaginary parts of the
permittivity exhibited a low frequency dispersion which has been attributed to hopping of polarons and bipolarons in PANI
and its composites. The thermal stability was checked by thermogravimetric analysis (TGA) and was found to be enhanced due
to addition of MMT in the PANI. 相似文献
10.
The effect of cosolvent on micellization of hexadecyltrimethyl ammonium bromide (CTAB) in aqueous solutions was studied. The
conductivity of a mixture (cosolvent + water) as function of CTAB concentration was measured at different temperatures. Ethylene
glycol and ethanol were used as a cosolvent. The conductivity data were used to determine the critical micelle concentration
(CMC) and the effective degree of counterion dissociation of micelle in the temperature range 303.2 to 313.2 K. In all the
cases studied, a linear relationship between log([CMC]mix/mol dm−3) and the mass fraction of cosolvent in solvent mixture has been observed. The free energy (ΔG
mic
0
), enthalpy (ΔH
mic
0
), and entropy (ΔS
mic
0
) of micellization were determined using the temperature dependence of CMC. The dependence of these thermodynamic parameters
on solvent composition was determined. The standard free energy of micellization was found to be negative in all cases and
becomes less negative as the cosolvent content increases. The enthalpy and entropy of micellization are independent of temperature
in pure water, while ΔH
mic
0
and ΔS
mic
0
decrease dramatically with temperature in mixed cosolvents. Furthermore, the entropic contribution is larger than the enthalpic
one in pure water, while in the mixed solvents, the enthalpic contribution predominates.
The text was submitted by the authors in English. 相似文献
11.
M. N. Roy R. Chanda B. K. Sarkar 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(10):1737-1746
The densities and viscosities of several sulfates, viz., ammonium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate,
zinc sulfate and cadmium sulfate in aqueous binary mixtures of formamide (FA) have been determined at 298.15, 308.15, and
318.15 K and at atmospheric pressure. The ultrasonic speeds of the electrolytic solutions have also been measured at 298.15
K. Apparent molar volumes (ϕ
V
), viscosity B-coefficients and adiabatic compressibilities (K
S) of these electrolytic solutions were calculated from the experimental densitiy, viscosity and acoustic data. The density
and viscosity data were evaluated by using Masson’s and Jones-Dole equation respectively; the derived parameters have been
analyzed in terms of ion-ion and ion-solvent interactions. The structure making/breaking capacities of the electrolytes have
been inferred from the sign of (∂2ϕ
V
0/∂T
2)
P
. The results showed that all the electrolytes act as structure-makers in these media. Also the compressibility data indicated
electrostriction of the solvent molecules around the cations. The activation parameters of viscous flow were also determined
and discussed by the application of transition state theory. 相似文献
12.
Malyanah M. Taib Abobakr K. Ziyada Cecilia Devi Wilfred Thanapalan Murugesan 《Journal of solution chemistry》2012,41(1):100-111
Densities and refractive indices have been measured for binary mixtures of 1-propyronitrile-3-hexylimidazolium bromide + ethanol
in the temperature range 293.15–323.15 K. From the experimental data the excess molar volume V
E, refractive index deviation Δn
D, and the coefficient of thermal expansion α were calculated and fitted to fifth- and third-order Redlich–Kister type equations, respectively. Using the measured densities,
the apparent molar volumes (V
ϕ
), limiting apparent molar volumes (Vf0V_{\phi}^{0}) and limiting apparent molar expansivities (Ef 0E_{\phi} ^{0}) were also determined and the details are discussed. 相似文献
13.
H. Bendiab G. Roux-Desgranges A. H. Roux J. -P. E. Grolier D. Patterson 《Journal of solution chemistry》1994,23(2):307-323
Densities and heat capacities of ternary systems were determined at 25°C. The ternary systems consisted of: a polar molecule (component 1) + a mixture of alkanes (components 2 and 3) of different sizes and shapes. Five such systems were studied: chlorobenzene + cyclohexane + n-heptane; chlrobenzene + cyclohexane + n-hexadecane; chlorobenze + cyclohexane + isooctane; chlorobenzene + isooctane + n-heptane; 1-chloronaphthalene + isooctane + n-heptane. The excess molar volumes and heat capacities were obtained along dilution lines by component 1 (chlorobenzene or 1-chloronaphthalene) of mixtures of components 2 and 3 (at fixed component 2 mole fraction X2). Unexpectedly the excess heat capacities C
p1(23)
E
of the pseudo-binaries {1+(2+3)} do not always fall between the two (limiting) curves of C
p12
E
and C
p13
E
corresponding to the two binaries {1+2} and {1+3}. Instead, especially for {chlorobenzene + cyclohexane + an n-alkane} the C
p1(23)
E
curves are displaced toward less negative values, even beyond the limiting values corresponding to the binaries. This correlates semi-quantitatively with the negative C
p23
E
of the binary {2+3}.Presented at the Symposium, 76th CSC Congress, Sherbrooke, Quebec, May 30-June 3, 1993, honoring Professor Donald Patterson on the occasion of his 65th birthday. 相似文献
14.
M. G. Myskiv E. A. Goreshnik V. K. Pecharskii V. V. Oljinik 《Journal of Structural Chemistry》1994,35(1):82-86
We have carried out synthesis and X-ray structural study (DARCH, MoKα radiation, graphite monochromator, ϕ/2ϕ, scan mode, 2ϕ<-65°) of the CuNo3·C6H11N π-complex (a=14.346(6), c=16.719(7) δA, space group I41/a, and Z=16). The bifunctional (bridge and chelate) tridentate molecule of diallylamine cross-links the inorganic component
into infinite spirals oriented along the axes 41 and 43. The mainly covalent character of the Cu+...No
3
-
bond affects the hydrogen bond strength and the efficiency of the metal-olefin interaction.
I. Franko Lvov State University. Translated fromZhumal Strukturmoi Khimii, Vol. 35, No. 1, pp. 90–94, January–February, 1994.
Translated by T. Yudanova 相似文献
15.
The hydrolytic rate constants of thep-nitrophenyl esters of acetic, octanoic, dodecanoic and hexadecanoic acids in six aquiorgano binary mixtures of graded compositions
at various initial substrate concentrations were measured and discussed in terms of the hydrophobic-lipophilic interactions
between the substrate molecules, and the organic cosolvents which were MeOH, Me2SO, 1, 4-dioxane, 1,2-dimethoxyethane,n-propanol andt-butanol. The accelerating or retarding effects of the organic cosolvents on the rate constants of hydrolysis were found to
be directly related to the lipophilicities of the solvents which were changed either by changing the content (ϕ) or the nature
of the organic cosolvent. The classification or ordering of the six solvents on the basis of their solvent effects were found
to conform to the lipophilicity order derived from Rekker's Σf values. The results support the proposition that lipophilic interactions can play an important role in solvent effects of
aqueous binaries. 相似文献
16.
V. M. Byakov L. V. Lanshina O. P. Stepanova S. V. Stepanov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(7):1260-1262
The cryoscopic and radiospectroscopic data revealed that carbon tetrachloride (CCl4)
n
agglomerates (n ≥ 4) could form in cyclohexane and carbon tetrachloride itself. Additional arguments in favor of the formation of similar
CCl4 agglomerates in isooctane were presented by analyzing the available data on positron annihilation in CCl4 solutions in isooctane. 相似文献
17.
The formation constant of the mononitratouranyl complex was studied spectrophotometrically at temperatures of 25, 40, 55,
70, 100 and 150 °C (298, 313, 328, 343, 373 and 423 K). The uranyl ion concentration was fixed at approximately 0.008 mol⋅kg−1 and the ligand concentration was varied from 0.05 to 3.14 mol⋅kg−1. The uranyl nitrate complex, UO2NO3+, is weak at 298 K but its equilibrium constant (at zero ionic strength) increases with temperature from log 10
β
1=−0.19±0.02 (298 K) to 0.78±0.04 (423 K). 相似文献
18.
Relative enthalpies for low-and high-temperature modifications of Na3FeF6 and for the Na3FeF6 melt have been measured by drop calorimetry in the temperature range 723–1318 K. Enthalpy of modification transition at 920
K, δtrans
H(Na3FeF6, 920 K) = (19 ± 3) kJ mol−1 and enthalpy of fusion at the temperature of fusion 1255 K, δfusH(Na3FeF6, 1255 K) = (89 ± 3) kJ mol−1 have been determined from the experimental data. Following heat capacities were obtained for the crystalline phases and for
the melt, respectively: C
p(Na3FeF6, cr, α) = (294 ± 14) J (mol K)−1, for 723 = T/K ≤ 920, C
p(Na3FeF6, cr, β) = (300 ± 11) J (mol K)−1 for 920 ≤ T/K = 1233 and C
p(Na3FeF6, melt) = (275 ± 22) J (mol K)−1 for 1258 ≤ T/K ≤ 1318. The obtained enthalpies indicate that melting of Na3FeF6 proceeds through a continuous series of temperature dependent equilibrium states, likely associated with the production of
a solid solution.
相似文献
19.
The solubility and the physicochemical properties (densities, viscosities, refractive indices, conductivities and pH) in the
liquid-solid metastable system (NaCl-KCl-CaCl2-H2O) at 308.15 K have been investigated using the isothermal evaporation method, and the dry-salt phase diagram, water-phase
diagram, and the diagram of physicochemical properties vs. composition in the system were plotted. One three-salt cosaturated point, three metastable solubility isotherm curves, and
three crystallization regions corresponding to sodium chloride, potassium chloride and calcium chloride tetrahydrate were
formed, and neither solid solution nor double salts were found. On the basis of the extended Harvie-Weare (HW) model and its
temperature-dependent equation, the values of the Pitzer parameters β(0), β(1), C
ϕ for NaCl, KCl and CaCl2, the mixing ion-interaction parameters θNa,K, θNa,Ca, θK,Ca, ΨNa,K,Cl, ΨNa,Ca,Cl, ΨK,Ca,Cl, and the Debye-Hückel parameter A
ϕ and the chemical potentials of the minerals in the quaternary system at 308.15 K were fitted, and the predictive solubility
based on the temperature-dependent equation and the chemical potentials of the minerals agrees well with the experimental
data. 相似文献
20.
E. Makrlík P. Vaňura M. Daňková 《Journal of Radioanalytical and Nuclear Chemistry》1999,242(1):185-187
From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium 2Li+(aq)+SrL2
2+(nb) 2LiL+(nb)+Sr2+(aq) taking place in the two-phase water-nitrobenzene system (L=15-crown-5; aq=aqueous phase, nb=nitrobenzene phase) was evaluated
as logK
ex
(2Li+;SrL2
2+)=−3.7. Further, the stability constant of the 15-crown-5—lithium complex in nitrobenzene saturated with water was calculated:
log βnh(LiL+)=7.0. 相似文献