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P. Cabildo R.M. Claramunt D. Sanz M.C. Foces-Foces F. Hernandez Cano J. Catalan J. Elguero 《Tetrahedron》1985,41(2):473-478
Crystal structures of 1-(1-adamantyl)pyrazole, 1a, and 1-(1-adamantyl-3-ol)-4-nitropyrazole, 2a, have been solved by X-ray analysis. The space groups and cell parameters are P21, a, 7.4021(3), b, 10.7529(5),c, 6.9651(2)Å, β, 90.206(3)° for 1a with Z = 2 and P2/n, a, 31.1172(14), b, 6.8506(1), c, 12.0313(3)Å, β 94.873(3)° for 2a with Z = 8. Refinements were carried out down to R values of 0.043 (Rw, = 0.046) and 0.079 (Rw = 0.061) for the 951 (2σ(I)) and 2461 (3σ(I)) observed reflections respectively. The conformation about the bond between the heterocycle and the carbocycle is discussed on theoretical grounds INDO calculations): the adamantane behaves as a free rotor. The stcricinteractions of the adamantyl residue with the methyl substituents in 2- and 5-position of pyrazole are apparent in the C-13 chemical shifts. 相似文献
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Pilar Cabildo Concepción López Marta Pérez-Torralba M. Rosario Torres José Elguero 《Journal of Molecular Structure》2011,985(1):75-81
3-Bromo-1-methyl-7-nitro-1H-indazole (1), 3-bromo-2-methyl-7-nitro-2H-indazole (2) and 3,7-dinitro-1(2)H-indazole (3) have been synthesized and characterized by X-ray diffraction, 13C and 15N NMR spectroscopy in solution and in solid-state. The dihedral angles obtained in the crystal structures are in good agreement with the molecular parameters calculated using DFT B3LYP calculations employing the 6-311++G(d,p) basis set. Compounds 1 and 2 present intermolecular halogen bonds between the bromine and the oxygen atoms of the nitro group and in compound 3 inter- and intramolecular hydrogen bonding exists. 相似文献
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Quintanilla E Dávalos JZ Abboud JL Alcamí M Cabildo MP Claramunt RM Elguero J Mó O Yáñez M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(6):1826-1832
Fourier transform ion cyclotron resonance spectroscopy (FT ICR) techniques, including collision-induced dissociation (CID) methodology, were applied to the study of the gas-phase protonation of pivalaldehyde (1) and 1-adamantanecarbaldehyde (2). A new synthetic method for 2 was developed. The experiments, together with a thorough computational study involving ab initio and density functional theory (DFT) calculations of high level, conclusively show that upon monoprotonation in the gas phase, compound 1 yields monoprotonated methyl isopropyl ketone 3. The mechanism of this gas-phase acid-catalyzed isomerization is different from that reported by Olah and Suryah Prakash for the reaction in solution. In the latter case, isomerization takes place through the diprotonation of 1. 相似文献
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Maria das Dores M.C. Ribeiro da Silva Manuel A.V. Ribeiro da Silva Vera L.S. Freitas Maria Victoria Roux Pilar Jiménez Manuel Temprado Juan Z. Dávalos Pilar Cabildo Rosa M. Claramunt José Elguero 《The Journal of chemical thermodynamics》2009,41(12):1400-1407
A thermochemical and thermophysical study has been carried out for crystalline barbital [5,5′-diethylbarbituric acid]. The thermochemical study was made by static bomb combustion calorimetry, from which the standard () molar enthalpy of formation of the crystalline barbital, at T = 298.15 K, was derived as −(753.0 ± 1.8) kJ · mol−1. The thermophysical study was made by differential scanning calorimetry over the temperature interval (265 to 470) K. A solid–solid phase transition was found at T = 413.3 K. The vapour pressures of the crystalline barbital were measured at several temperatures between T = (355 and 377) K, by the Knudsen mass-loss effusion technique, from which the standard molar enthalpy of sublimation, at T = 298.15 K was derived as (117.3 ± 0.6) kJ · mol−1. The combination of the experimental results yielded the standard molar enthalpy of formation of barbital in the gaseous phase, at T = 298.15 K, as −(635.8 ± 1.9) kJ · mol−1. This value is compared and discussed with our theoretical calculations by several methods (Gaussian-n theories G2 and G3, complete basis set CBS-QB3, density functional B3P86 and B3LYP) by means of atomization and isodesmic reaction schemes. 相似文献
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Maria das Dores M.C. Ribeiro da Silva Manuel A.V. Ribeiro da Silva Vera L.S. Freitas Maria Victoria Roux Pilar Jiménez Juan Z. Dávalos Pilar Cabildo Rosa M. Claramunt Elena Pinilla M. Rosario Torres José Elguero 《The Journal of chemical thermodynamics》2010,42(4):536-544
Thermochemical and thermophysical studies have been carried out for crystalline 3,4,4′-trichlorocarbanilide. The standard (p° = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, for the crystalline 3,4,4′-trichlorocarbanilide (TCC) was experimentally determined using rotating-bomb combustion calorimetry, as ?(234.6 ± 8.3) kJ · mol?1. The standard enthalpy of sublimation, at the reference temperature of 298.15 K, was measured by the vacuum drop microcalorimetric technique, using a High Temperature Calvet Microcalorimeter as (182.1 ± 1.7) kJ · mol?1. These two thermochemical parameters yielded the standard molar enthalpy of formation of the studied compound, in the gaseous phase, at T = 298.15 K, as ?(52.5 ± 8.5) kJ · mol?1. This parameter was also calculated by computational thermochemistry at M05-2X/6-311++G7 and B3LYP/6-311++G(3df, 2p) levels, with a deviation less than 4.5 kJ · mol?1 from experimental value. Moreover, the thermophysical study was made by differential scanning calorimetry, DSC, over the temperature interval between T = 263 K and its onset fusion temperature, T = (527.5 ± 0.4) K. A solid–solid phase transition was found at T = (428 ± 1) K, with the enthalpy of transition of (6.1 ± 0.1) kJ · mol?1. The X-ray crystal structure of TCC was determined and the three-centred N–H?OC hydrogen bonds present analyzed. 相似文献
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J. Torres J. L. Lavandera P. Cabildo R. M. Claramunt J. Elguero 《Journal of heterocyclic chemistry》1988,25(3):771-782
Twenty symmetrical and asymmetrical 1,2-bisazolylethanes have been obtained from azoles and 1,2-dibromoethane or 1-chloro-2-(pyrazol-1-yl)ethane by phase transfer catalysis (PTC). The 1H and 13C nmr properties are reported and the chemical shifts of the ethylene carbon atoms discussed using an additive model. 相似文献
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Maria das Dores M.C. Ribeiro da Silva Manuel A.V. Ribeiro da Silva Vera L.S. Freitas Maria Victoria Roux Pilar Jimnez Juan Z. Dvalos Pilar Cabildo Rosa M. Claramunt Jos Elguero 《The Journal of chemical thermodynamics》2008,40(9):1378-1385
Thermophysical and thermochemical studies have been carried out for crystalline parabanic acid. The thermophysical study was made by differential scanning calorimetry, DSC, over the temperature interval between T = (263 and 473) K. Two phase transitions were found: at T = (392.3 ± 1.6) K with the enthalpy of transition of (2.1 ± 0.4) kJ · mol−1 and at T = (509.8 ± 1.5) K, when the compound was scanned to its fusion temperature. The standard (p = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, for crystalline parabanic acid was determined using static-bomb combustion calorimetry as −(590.2 ± 1.0) kJ · mol−1. The standard molar enthalpy of sublimation, at T = 298.15 K, was derived from the variation of their vapour pressures, measured by the Knudsen-effusion method, with the temperature. These two thermochemical parameters yielded the standard molar enthalpy of formation in the gaseous phase, at T = 298.15 K, as −(470.8 ± 1.2) kJ · mol−1. 相似文献
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Nieto Carla I. Cabildo Pilar Claramunt Rosa M. Cornago Pilar Sanz Dionisia Torralba M. Carmen Torres M. Rosario Ferraro Marta B. Alkorta Ibon Marín-Luna Marta Elguero José 《Structural chemistry》2016,27(2):705-730
Structural Chemistry - Structural data are reported on sixteen ketoenols of β-diketones: solution NMR, solid-state NMR (CPMAS and MAS) and X-ray crystallography (four compounds, where three... 相似文献