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Ysaías J. Alvarado José Caldera-Luzardo Carlos De La Cruz Gladys Ferrer-Amado Elba Michelena Pedro Silva 《Journal of solution chemistry》2006,35(1):29-49
High-precision densitometry measurements of solutions of thioxanten-9-one (TX) in 1,4-dioxane, DMSO, toluene, and benzene
have been obtained at 293.15, 303.15, 313.15, 323.15, 333.15, and 343.15K. The partial molar volumes of TX (
) and the corresponding values at infinite dilution (
) were determined. The partial molar expansibility (
) of TX at infinite dilution in each solvent is temperature independent. Dynamic electronic polarizabilities
of TX in each aprotic solvent were determined by the Singer–Garito approach. These values are in excellent concordance with
the theoretical value for TX of 2.611×10−23cm3 estimated here using DFT/B3LYP/6-311++G(d,p). The partial molar volumes of TX at infinite dilution were calculated and interpreted
in terms of the Scale Particle Theory (SPT). The solvent influence on the partial molar volume of TX was found to be due mainly
to cavity formation and intermolecular dispersion forces. 相似文献
3.
Merlin Rosales Janeth Navarro Ligbel Sánchez Angel González Ysaías Alvarado Raúl Rubio Carlos De La Cruz Tamara Rajmankina 《Transition Metal Chemistry》1996,21(1):11-15
Summary The complex [RuH(CO)(NCMe)2(PPh3)2]BF4 (1) is an efficient and regioselective catalyst precursor for the hydrogenation of polyaromatic nitrogen compounds such as quinoline (Q), isoquinoline (iQ), indole (ln), 5,6- and 7,8-benzoquinoline (BQ) and acridine (A) under relatively mild reaction conditions (125 °C, 4 atm H2). The order of individual initial rates was: A > Q > 5,6-BQ > 7,8-BQ > ln > iQ, reflecting both steric and electronic effects. For the regioselective homogeneous hydrogenation of A to 9,10-dihydroacridine (DHA) catalysed by complex (1), a kinetic study was carried out; the experimentally determined rate law was r = k
1 [Ru] [H2]. These findings are consistent with a mechanism involving the hydrogenation of [RuH(CO)(A)(NCMe)(PPh3)2]BF4 to yield DHA and the unsaturated species [RuH(CO)(NCMe)(PPh3)2]BF4 in the rate-determining step. 相似文献
4.
Ysaías J. Alvarado Néstor Cubillán María G. Leal Paola H. Labarca Elba Michelena Yovani Marrero Ponce 《Journal of solution chemistry》2007,36(9):1139-1155
The values of electronic polarizability of quinoline and isoquinoline in extremely diluted liquid solution are reported in this paper. These were obtained by means of three new strategies based on UV-visible-NIR spectroscopy, the Kramers-Krönig relations, high precision densitometry and high exactitude refractometry, which are called here Arakawa’s Approximation (AA), Optical Substractive Approximation (OSA) and Optical Differential Approximation (ODA). In general the static electronic polarizability values of solute molecules obtained by ODA and OSA are in excellent agreement with the reported theoretical values at the Density Functional Theory (DFT) level and the Atom monopole-dipole model, but strong discrepancies were observed with the experimental values previously reported for quinoline and isoquinoline using refractometric and electro-optic methods. These differences were interpreted and analyzed in terms of dielectric intermolecular forces, resonant and pre-resonant effects. The AA method is shown to fail in predicting the polarizability of the quinoline and isoquinoline molecules. 相似文献
5.
Ysaías J. Alvarado Néstor Cubillán Esker Chacín-Molero Gladys Ferrer-Amado Paola Hernández-Labarca Wendy Velazco José Ojeda-Andara Yovani Marrero-Ponce Federico Arrieta 《Journal of solution chemistry》2010,39(2):277-290
The partial molar volumes of indole(Ind) at infinite dilution (V2¥V_{2}^{\infty}) in carbon tetrachloride (CCl4), acetonitrile (ACN) and tetrahydrofuran (THF) as solvents, were estimated from densitometry measurements at 293.15 K. The
results indicate that $V_{2}^{\infty}\mbox{(ACN)}>V_{2}^{\infty}\mbox{(CCl$V_{2}^{\infty}\mbox{(ACN)}>V_{2}^{\infty}\mbox{(CCl
$\approx V_{2}^{\infty}\mbox{(THF)}$\approx V_{2}^{\infty}\mbox{(THF)}. The values determined in this study are close to the values calculated from reported density for Ind in the solid state.
In order to make a comparison the partial molecular volume of benzimidazole (Bim) and benzothiophene (BT) in solvents with
appropriate solubility were measured too, and the results have revealed that $V_{2}^{\infty}\mbox{(BT)}>V_{2}^{\infty}\mbox{(Ind)}$V_{2}^{\infty}\mbox{(BT)}>V_{2}^{\infty}\mbox{(Ind)} in CCl4 and $V_{2}^{\infty}\mbox{(Ind)}>V_{2}^{\infty}\mbox{(Bim)}$V_{2}^{\infty}\mbox{(Ind)}>V_{2}^{\infty}\mbox{(Bim)} in THF. In this work the role of solvent reorganization around to solute cavity, and specific and nonspecific interactions
on the volumetric behavior of these molecules in solution are discussed using the Terasawa-Itsuki-Arakawa model, the Lee-Graziano
model, molar volumes of solutes calculated at the DFT-B3LYP/cc-pVTZ and aug-cc-pVTZ level in the gas phase and considering solvent presence with the Onsager’s reaction field, and the van der Waals
volume. This analysis suggests that the molecular volumes of solutes are overestimated by the quantum methods employed in
this work and that the volumetric contribution from the van der Waals components to the limiting partial molecular volumes
of solutes is important, with the exception of Ind in CCl4 where the solvent reorganization is the dominant factor. 相似文献
6.
Alías FM Daff PJ Paneque M Poveda ML Carmona E Pérez PJ Salazar V Alvarado Y Atencio R Sánchez-Delgado R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(22):5132-5146
Nucleophilic attack of the beta-carbon of an Ir(III)-alkenyl functionality onto the alpha-carbon of a coordinated nitrile- or aldehyde occurs intramoleculary to yield initially iridacyclic structures. Nitriles give rise to isolable complexes that contain delocalized five-membered rings (iridapyrroles, e.g. 3'-8') in a reaction catalyzed by H2O (for some of these syntheses, Ir(III)-eta 3-allyl derivatives may be used as the source of the Ir(III)-alkenyl moiety). In contrast, the alkenyl-to-aldehyde C-C coupling gives transient iridacycles that evolve by a fast alkyl-to-alkylidene migration and beta-H elimination. The end products (13* and 14*) contain an elaborated chelating alkoxide-olefin ligand. Addition of [H(OEt2)2][BAr'4] to the iridapyrroles effects stereospecific protonation of the beta-ring carbon. Those iridapyrroles which contain an additional metal-alkyl functionality (e.g. 3a*, alkyl = C2H5) afford highly reactive cationic alkyl-alkylidene intermediates that evolve instantaneously by migratory insertion/beta-H elimination. The end products also contain an elaborated, chelating ligand, although this time with an olefin and imine terminus compared with the previous ligand. Contrary to this result, protonation of the hydride-iridapyrrole complex 8a* in weakly coordinating solvents permits isolation of two unusual cationic cis-hydride-alkylidene compounds 11*, which undergo reversible 1,2-H shifts. 相似文献
7.
Ysa��as J. Alvarado Joanna Baricelli Jos�� Caldera-Luzardo N��stor Cubill��n Gladys Ferrer-Amado Yovani Marrero-Ponce Victoria Mancilla Miguel A. Rocafull Jos�� Ojeda-Andara Luz E. Thomas Joan Vera-Villalobos Miguel Morales-Toyo 《Journal of solution chemistry》2011,40(1):26-39
The solubilities in water (W) and in 3 mol?L?1 aqueous acetonitrile at 298.15 K of thiophene-2-, furan-2- and pyrrole-2-carboxaldehyde phenylhydrazone along with their nitro and 2,4-dinitro derivatives, referred to as PCT, PCF, PCP, NPCT, NPCF, NPCP, DPCT, DPCF and DPCP, respectively, are reported. The standard Gibbs energy of transfer from W to solvent mixtures ( $\Delta G^{\mathrm{transf}}_{\mathrm{W-mix}}$ ) was estimated for each solute. The results indicate that the transfer process for all systems is a spontaneous process. Calculations under the scaled-particle theory suggest that the work of cavity creation (????G c), which is associated with the transfer of the phenylhydrazone from W to mix, dominates the magnitude of $\mathrm {\Delta} G^{\mathrm{transf}}_{\mathrm{W-mix}}$ . UV spectroscopic measurements suggest that these compounds bind calf thymus(CT)-DNA via intercalation mode in a buffer?C3 mol?L?1 acetonitrile solution. The binding constant (K b) depends on the nitro-substitution on the phenyl moiety and the electronegativity of the heteroatom in the heterocyclic ring. The corresponding Gibbs energy of binding ( $\Delta G_{\mathrm{DNA-B}}^{0}$ ) of phenylhydrazone derivatives to CT-DNA shows a marked dependence with ????G c. The anticancer activity on human breast cancer cell lines MDA-231, MDA-435 and HT-29 human colon adenocarcinoma cell line was evaluated for the compounds NPCT, NPCF, DPCT and PCT. 相似文献
8.
Merlin Rosales Ysaías Alvarado Nelya Gallardo Raúl Rubio 《Transition Metal Chemistry》1995,20(3):242-245
Summary Kinetic and mechanistic studies of the homogeneous hydrogenation of cyclohexane were carried out using the cationic complex [RuH(CO)(NCMe)2(PPh3)2]BF4 as the catalyst precursor, which was very efficient under mild reaction conditions in xylene solution. The experimental rate law was found to ber = {K
1
K
2
k
3/([MeCN]+K
1–(1+K
2)[C6H10]}[Ru][C6H10][H2], which became {K
2
k
3/(1 +K
2)}[Ru][H2] at high cyclohexane concentrations. The activation parameters were calculated. The kinetic data are consistent with a mechanism involving the oxidative addition of hydrogen as the rate-determining step of the catalytic cycle. 相似文献
9.
Merlin Rosales Ysaías Alvarado Mirixa Boves Raúl Rubio Humberto Soscún Roberto A. Sánchez-Delgado 《Transition Metal Chemistry》1995,20(3):246-251
Summary A kinetic study of the regioselective homogeneous hydrogenation of quinoline (Q) to 1,2,3,4-tetrahydroquinoline (THQ) was carried out using the cationic complex [RuH(CO)(NCMe)2(PPh3)2]BF4 (1) as the precatalyst. The experimentally determined rate law wasr = {k
2
K
1/(1+K
1[H2])}[Ru0][H2]2, which becomesr = {k
2
K
1[Ru0]–[H2]2 at low hydrogen concentrations (k
2
K
1 = 28.5M
–2 s–1 at 398 K). The corresponding activation parameters were found to be H
= 42 + 6 kJ mol–1, S
= – 115 ± 2JK–1mol–1 and G
= 92 ± 8 kJ mol–1. Complex(1) was found to react with Q in CHCl3 under reflux to yield [RuH(CO)(NCMe)(N-Q)(PPh3)2]BF4
(2) which was also isolated from the hydrogenation runs. These experimental findings, together with the results ofab initio self-consistent-field molecular orbital calculations on the free organic molecules involved, are consistent with a mechanism involving a rapid and reversible partial hydrogenation of(2) to yield the corresponding dihydroquinoline (DHQ) species [RuH(CO)(NCMe)(DHQ)(PPh3)2]BF4
(4), followed by a rate-determining second hydrogenation of DHQ to yield [RuH(CO)(NCMe)(THQ)(PPh3)2]BF4
(3). 相似文献
10.
Ysaías J. Alvarado José Caldera-Luzardo Gladys Ferrer-Amado Victoria Mancilla-Labarca Elba Michelena 《Journal of solution chemistry》2007,36(1):1-11
High-precision densitometry and high-accuracy refractometry measurements of extremely dilute solutions of the thiophene-2-
(TCPH), pyrrole-2- (PCPH) and furan-2-carboxaldehyde-phenylhydrazone (FCPH) compounds in acetonitrile have been obtained at
293.15 K. The partial molar volumes V
2^∞ of each compound at infinite dilution were determined. The apparent molar refraction of these solutes at infinite dilution
at 293.15 K has been experimentally determined within the Kohner-Geffcken-Grunwald-Haley approximation. The volumetric and
refractometric results were interpreted in terms of the Pauling electronegativity and intrinsic molar volume of the heteroatom,
and the aromaticity of the heterocyclic rings. The experimental results indicate that solute-solute interactions are negligible
within the concentration range studied. Theoretical calculations at the DFT-B3LYP/6−311++G(3d,3p) level of molecular volumes
support the interpretation that the volumetric contribution from the solute-solvent interactions to the limiting partial molar
volumes of solutes are very small and thus solute molecules are isolated in this medium. 相似文献