The present work reports the experimental determination of the standard (po = 0.1 MPa) molar enthalpies of formation in the condensed and gaseous phases, at T = 298.15 K, of 5- and 6-nitroindazole. These results were derived from the measurements of the standard molar energies of
combustion, using a static bomb calorimeter and from the standard molar enthalpies of sublimation derived by the application
of Clausius–Clapeyron to the temperature dependence of the vapour pressures measured by the Knudsen effusion technique. The
results are interpreted in terms of the energetic contributions of the nitro groups in the different positions of the aromatic
The standard (p0=0.1 MPa) molar enthalpy of formation of 1-cyanoacetylpiperidine, in the crystalline state, at T=298.15 K, has been derived from measurements of its standard massic energy of combustion, by static bomb combustion calorimetry,
as ΔfHm0=−217.1±1.4 kJ mol−1. The standard molar enthalpy of sublimation was measured, at T=298.15 K, by the microcalorimetric sublimation technique as ΔcrgHm0=103.5±1.9 kJ mol−1.
The standard (po=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.
Authors:Maria Ribeiro da Silva, Joana Cabral, Chelsea Givens, Stephanie Keown, and W. Acree
The standard (p0=0.1 MPa) molar enthalpies of formation, in the gaseous phase, at T-298.15 K, for 2,5-dimethylpyrazine (2,5-DMePz) and for the two dimethylpyrazine-N,N′-dioxide derivatives, 2,3-dimethylpyrazine-1,4-dioxide (2,3-DMePzDO) and 2,5-dimethylpyrazine-1,4-dioxide (2,5-DMePzDO), were
derived from the measurements of standard massic energies of combustion, using a static bomb calorimeter, and from the standard
molar enthalpies of vaporization or sublimation, measured by Calvet microcalorimetry.
The mean values for the molar dissociation enthalpy of the nitrogen-oxygen bonds, 〈DHm0〉(N-O), were derived for both N,N′-dioxide compounds. These values are discussed in terms of the molecular structure of the two N,N′-dioxide derivatives and compared with 〈DHm0〉(N-O) values previously obtained for other N-oxide derivatives.
Authors:Joana Cabral, Ricardo Monteiro, Marisa Rocha, Luís Santos, William Acree, and Maria Ribeiro da Silva
The standard (p° = 0.1 MPa) energies of combustion in oxygen, at T = 298.15 K, for the solid compounds 2-methylpyridine-N-oxide (2-MePyNO), 3-methylpyridine-N-oxide (3-MePyNO) and 3,5-dimethylpyridine-N-oxide (3,5-DMePyNO) were measured by static-bomb calorimetry, from which the respective standard molar enthalpies of formation
in the condensed phase were derived. The standard molar enthalpies of sublimation, at the same temperature, were measured
by Calvet microcalorimetry. From the standard molar enthalpy of formation in gaseous phase, the molar dissociation enthalpies
of the N–O bonds were derived, and compared with values of the dissociation enthalpies of other N–O bonds available for other