Search

The standard (p° = 0.1 MPa) molar energies of combustion in oxygen, at T = 298.15 K, of 1-naphthalenemethanol and 2-naphthalenemethanol were measured by static bomb calorimetry. The values of the standard molar enthalpies of sublimation, at T = 298.15 K, were obtained by Calvet microcalorimetry. Combining these results the standard molar enthalpies of formation of the compounds, in the gas phase, at T = 298.15 K, have been calculated. [image omitted] (kJ·mol-1) [image omitted] (kJ·mol-1) [image omitted] (kJ·mol-1) 1-Naphthalenemethanol 132.5 ± 2.9 102.3 ± 1.9 30.2 ± 3.5 2-Naphthalenemethanol 134.9 ± 3.3 106.0 ± 2.1 28.9 ± 3.9 Density functional theory with the B3LYP functional and two different basis sets, 6-31G(d) and 6-311G(d, p), were used to optimize the geometries of the two substituted naphthalenes. Additionally, ab initio second order Møller-Plesset calculations were also used at the MP2(FULL)/6-31G(d), MP2/6-31 + G(d), and MP2(FULL)/6-31 + G(d) levels. The calculation of the energies of appropriate isodesmic reactions allowed the estimation of the standard molar enthalpies of formation in the gas phase for the compounds. The experimental measurements and both sets of quantum chemical calculations were in good agreement for both isomers. [ABSTRACT FROM AUTHOR]

The standard molar enthalpies of combustion, sublimation, and formation of three nitrogen-containing heterocycles, namely, 2-benzimidazolinone, 2-benzoxazolinone and 3-indazolinone were determined calorimetrically. The standard ( p °?=?0.1?MPa) molar enthalpies of formation in the gas phase were derived from the standard molar enthalpies of combustion, in oxygen, at T ?=?298.15?K, measured by static bomb combustion calorimetry and from the standard molar enthalpies of sublimation at T ?=?298.15?K, measured by Calvet microcalorimetry. Møller–Plesset calculations at the MP2 level and density functional calculations with the B3LYP functional and extended basis sets were also performed to determine the energetically preferred tautomeric form of the molecules. The results were qualitatively independent of the calculational level, where in general the DFT calculations were in better agreement with experiment than those from MP2. The gas and solid phase enthalpic differences between imines and amides, wherein –CH=N- is contrasted with –CONH-, have been studied and roughly constant values have been found. [ABSTRACT FROM AUTHOR]