Authors:Iulia Contineanu, Loredana Chivu, and Şt. Perişanu
The energies of combustion of crystalline L-α-glutamic and 6-aminohexanoic acids were measured in a static bomb adiabatic calorimeter, in pure oxygen at 3040 kPa. Corrections
were made for the heats due to the ignition of sample and for the nitric acid formation. The derived enthalpies of formation
for L-α -glutamic and 6-aminohexanoic acids are ΔfHcr0= -1002.61.1 kJ mol-1and ΔfHcr0= -641.61.2 kJ mol-1, respectively. The data of enthalpy of formation are compared with literature values and with estimated values by means of
group additivity, using parameters recommended by Domalski and Hearing.
Authors:Yu. Maksimuk, V. Sokolov, V. Sevruk, and P. Trahanov
The enthalpies of combustion for 4-formylbenzoic acid (I), 4-methylbenzyl alcohol (II), and trimethyl 1,2,4-benzenetricarboxylate
(III) were determined by the bomb calorimetry method. Enthalpies of sublimation for I and II were measured with a calorimeter.
The contributions of different substituents to the standard enthalpies of formation for benzene derivatives in the gas state
Authors:V. Lukyanova, T. Papina, K. Didenko, and A. Alikhanyan
The standard enthalpy of combustion of crystalline silver pivalate, (CH3)3CC(O)OAg (AgPiv), was determined in an isoperibolic calorimeter with a self-sealing steel bomb, ΔcH0 (AgPiv, cr)= −2786.9±5.6 kJ mol−1. The value of standard enthalpy of formation was derived for crystalline state: ΔfH0(AgPiv,cr)= −466.9±5.6 kJ mol−1. Using the enthalpy of sublimation, measured earlier, the enthalpy of formation of gaseous dimer was obtained: ΔfH0(Ag2Piv2,g)= −787±14 kJ mol−1. The enthalpy of reaction (CH3)3CC(O)OAg(cr)=Ag(cr)+(CH3)3CC(O)O.(g) was estimated, ΔrH0=202 kJ mol−1.
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.
Authors:L. Peng, X. Jiangjun, M. Fangquan, L. Xi, and Z. Chaocan
The standard molar enthalpy of combustion of cholesterol was measured at constant volume. According to value of ΔrUmθ(−14358.4±20.65 kJ mol−1), ΔrHmθ(−14385.7 kJ mol−1) of combustion reaction and ΔfHmθ(2812.9 kJ mol−1) of cholesterol were obtained from the reaction equation. The enthalpy of combustion reaction of cholesterol was also estimated
by the average bond enthalpies. By design of a thermo-chemical recycle, the enthalpy of combustion of cholesterol were calculated
between 283.15∼373.15 K. Besides, molar enthalpy and entropy of fusion of cholesterol was obtained by DSC technique.
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.
The standard (p0=0.1
MPa) molar enthalpies of formation, in the condensed phase, of nine linear-alkyl
substituted thiophenes, six in position 2- and three in position 3-, at T=298.15 K, were derived from the standard massic
energies of combustion, in oxygen, to yield CO2(g)
measured by rotating-bomb combustion calorimetry. The standard molar enthalpies
of vaporization of these compounds were measured by high temperature Calvet
Microcalorimetry, so their standard molar enthalpies of formation, in the
gaseous phase, were derived.
The results are discussed in terms
of structural contributions to the energetics of the alkyl-substituted thiophenes,
and empirical correlations are suggested for the estimation of the standard
molar enthalpies of formation, at T=298.15
K, for 2- and 3-alkyl-substituted thiophenes, both in the condensed and in
the gaseous phases.
Authors:O. Govin, V. Diky, G. Kabo, and A. Blokhin
A correlation formula to estimate chemical exergies of oil fractions and fuel mixtures from enthalpy of combustion and atomic
composition is developed. Heat capacity ofa mixture of 10 hydrocarbons was measured in the range 5–290 K. It was shown that
contribution of entropy of mixing to exergy of typical oil fractions is about –0.11% in the approximation of ideal solution,
and about –0.18% for a real solution.
Authors:Y. Xu-Wu, Z. Hang-Guo, S. Wu-Juan, W. Xiao-Yan, and G. Sheng-Li
The copper(II) complex of 6-benzylaminopurine (6-BAP) has been prepared with dihydrated cupric chloride and 6-benzylaminopurine.
Infrared spectrum and thermal stabilities of the solid complex have been discussed. The constant-volume combustion energy,
ΔcU, has been determined as −12566.92±6.44 kJ mol−1 by a precise rotating-bomb calorimeter at 298.15 K. From the results and other auxiliary quantities, the standard molar enthalpy
of combustion, ΔcHmθ, and the standard molar of formation of the complex, ΔfHmθ, were calculated as −12558.24±6.44 and −842.50±6.47 kJ mol−1, respectively.
The standard (p0=0.1
MPa) molar enthalpy of formation, ΔfH0m, for crystalline N-phenylphthalimide
was derived from its standard molar enthalpy of combustion, in oxygen, at
the temperature 298.15 K, measured by static bomb-combustion calorimetry,
as –206.03.4 kJ mol–1. The
standard molar enthalpy of sublimation, ΔgcrH0m
, at T=298.15 K, was derived, from high
temperature Calvet microcalorimetry, as 121.31.0 kJ mol–1.
The derived standard molar enthalpy of formation, in the gaseous state,
is analysed in terms of enthalpic increments and interpreted in terms of molecular