Thermochemical properties of two benzimidazole derivatives: 2-Phenyl- and 2-benzylbenzimidazole
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
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ABSTRACT: Molecular crystals of 2-phenylbenzimidazole, C13H10N2, exhibit a one-dimensional incommensurate structure. The Structure has been solved by charge flipping and refined using the superspace formalism in the (3 + 1) D superspace group C2/c(0b0) s0 with modulation wave-vector q = 0.368b*. The unit cell contains 8 molecules, each one disorderly occupying two configurations related by inversion center. The refinement based on a molecular model with two rigid-body parts per molecule includes up to second order Fourier amplitudes for the modulation. The displacive modulation involves a significant intra-molecular twist between the phenyl and the benzimidazole parts.Zeitschrift für Kristallographie 01/2006; 221(4):281-287. DOI:10.1524/zkri.2006.221.4.281 · 1.26 Impact Factor
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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.
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ABSTRACT: The standard (p∘=0.1MPa) massic energies of combustion, Δcu∘, for crystalline N-chloromethylphthalimide, N-(2-chloroethyl)phthalimide, N-(2-bromoethyl)phthalimide, and N-(3-bromopropyl)phthalimide were determined, at the temperature 298.15K, using a rotating-bomb combustion calorimeter. The standard molar enthalpies of sublimation, ΔcrgHm∘, at T=298.15K were determined for all compounds by Calvet microcalorimetry and for N-chloromethylphthalimide also derived from the variation with the temperature of its vapour pressures measured by the Knudsen effusion technique. The results obtained were as follows: −Δcu∘(cr)/(kJ·g−1)ΔcrgHm∘/(kJ·mol-1)N-Chloromethylphthalimide20720.1±4.5103.6±0.9N-(2-Chloroethyl)phthalimide22479.3±6.898.4±1.9N-(2-Bromoethyl)phthalimide18501.6±2.8108.7±1.0N-(3-Bromopropyl)phthalimide19965.8±5.4116.0±1.0These values were used to derive the standard molar enthalpies of formation of the compounds in their crystalline and gaseous phases, respectively. The derived standard molar enthalpies of formation, in the gaseous state, are analyzed in terms of enthalpic increments and interpreted in terms of molecular structure.The Journal of Chemical Thermodynamics 10/2007; 39(10):1363-1371. DOI:10.1016/j.jct.2007.03.009 · 2.42 Impact Factor