Article

Thermochemical properties of two benzimidazole derivatives: 2-Phenyl- and 2-benzylbenzimidazole

The Journal of Chemical Thermodynamics (Impact Factor: 2.3). 01/2005; 37(11):1168-1176. DOI: 10.1016/j.jct.2005.02.008

ABSTRACT The standard (p∘ = 0.1 MPa) molar enthalpy of formation for gaseous 2-phenylbenzimidazole (2-PhBIM) and 2-benzylbenzimidazole (2-BzBIM) were derived from the standard molar enthalpies of combustion, at T = 298.15 K, measured by static bomb calorimetry, and the standard molar enthalpy of sublimation, at T = 298.15 K, measured by Calvet microcalorimetry in the case of 2-phenylbenzimidazole or derived from the variation of the vapour pressures, determined by the Knudsen effusion technique, with temperatures between (393 and 412) K for 2-benzylbenzimidazole. Heat capacities, in the temperature ranges from (268.15 to 322.10) K for 2-phenylbenzimidazole and (270.15 to 316.02) K for 2-benzylbenzimidazole, were also measured with a differential scanning calorimeter. View Within Article

0 Bookmarks
 · 
85 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The structure and properties (crystallography, NMR, theoretical calculations) of the three N-unsubstituted benzazoles (1H-benzimidazoles, 1H-and 2H-indazoles, 1H-and 2H-benzotriazoles) have been reviewed for the period 2000–2012 with some results from previous years. The study of these compounds will greatly increase in the coming years and it is expected that the present review will contribute to it. In 1974 we published a paper entitled "The benzazoles (benzimidazole, indazole, benzotriazole): molecular structure and fundamental properties" [1] where the three stable parent compounds 1, 6, and 12 were compared (Figs. 1-3, the possible tautomers of compounds 1, 6, and 12 were not reported in the solid state). Nearly forty years later the situation has much changed and thousands of papers and several books have been published on these heterocycles. This review will be limited to: 1) compounds bearing protons on the nitrogen atoms, NH-benzazoles (Figs. 1-3); 2) structural and theoretically calculated physicochemical properties (synthetic aspects, reactivity, and biological properties will not be discussed); 3) the literature will cover mainly the 2000–2012 period, and 4) all our main contributions, published or in press, will be reported.
    Chemistry of Heterocyclic Compounds 05/2013; 49(49):177. · 0.63 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have investigated the energetic, structural, and other physical–chemical properties (aromaticity, intrinsic strain, hydrogen bond interaction) of 1,4-anthraquinone (1), its better known isomer 9,10-anthraquinone (2) and the derivatives 9-hydroxy-1,4-anthraquinone (3) and 9-methoxy-1,4-anthraquinone (4). In particular, the standard enthalpy of formation in the gas phase at 298.15 K of 1,4-anthraquinone was determined [ $\Updelta_{\text{f}}^{{}} H_{\text{m}}^{\text{o}} \left( {{\text{g}},{\mathbf{1}}} \right) \, = \, - 4 4. 9 { } \pm { 5}. 7\;{\text{kJ}}\;{\text{mol}}^{ - 1} ]$ Δ f H m o ( g , 1 ) = − 4 4.9 ± 5.7 kJ mol − 1 ] . Using isodesmic/homodesmotic reaction schemes, we have experimentally estimated: (i) the stabilization energy of 1 (162.2 ± 7.2 kJ mol−1) and 2 (193.2 ± 5.2 kJ mol−1), (ii) strength of intramolecular hydrogen bonding in 3 (HB = 79.8 ± 10.8 kJ mol−1), and (iii) additional strain energy due to peri-oxygen interaction in 4 (−34.2 ± 7.6 kJ mol−1). A computational study of these species, at the B3LYP/6-311++G(3df,2p) level, sheds light on structural, aromatic, intrinsic strain, or hydrogen bond effects and further confirmed the consistency of the experimental results.
    Structural Chemistry 12/2013; · 1.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The standard (p o=0.1 MPa) molar energies of combustion for the crystalline 1-benzyl-4-piperidinol and 4-piperidine-piperidine, and for the liquid 4-benzylpiperidine, were measured by static bomb calorimetry, in oxygen, at T=298.15 K. The standard molar enthalpies of sublimation or vaporization, at T=298.15 K, of these three compounds were determined by Calvet microcalorimetry. Those values were used to derive the standard molar enthalpies of formation, at T=298.15 K, in their condensed and gaseous phase, respectively.
    Journal of Thermal Analysis and Calorimetry - J THERM ANAL CALORIM. 01/2007; 90(3):865-871.