Standard molar enthalpies of formation of some methylfuran derivatives

The standard (p ^o = 0.1 MPa) molar enthalpies of formation \Updelta_\textf H_\textm^\texto ( \textl), {{\Updelta}}_{\text{f}} H_{\text{m}}^{\text{o}} ( {\text{l),}} of the liquid 2-methylfuran, 5-methyl-2-acetylfuran and 5-methyl-2-furaldehyde were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of vaporization of the three compounds. The standard (p ^o = 0.1 MPa) molar enthalpies of formation of the compounds, in the gaseous phase, at T = 298.15 K have been derived from the corresponding standard molar enthalpies of formation in the liquid phase and the standard molar enthalpies of vaporization. The results obtained were −(76.4 ± 1.2), −(253.9 ± 1.9), and −(196.8 ± 1.8) kJ mol⁻¹, for 2-methylfuran, 5-methyl-2-acetylfuran, and 5-methyl-2-furaldehyde, respectively.     

Standard molar enthalpies of formation of some trichloroanilines by rotating-bomb calorimetry

The standard ( p^o =  0.1 MPa) molar enthalpies of formation Δ_fH_m^o, at the temperature 298.15 K, for crystalline 2,3,4-, 2,4,5-, 2,4,6- and 3,4,5-trichloroaniline were derived from the molar enthalpies of combustion Δ_cH_m^oin oxygen using rotating bomb combustion calorimetry. The reaction products were CO₂(g), N₂(g), and HCl · 600H₂O(l). The standard molar enthalpies of sublimation Δ_cr^gH_m^oat T =  298.15 K were measured by Calvet microcalorimetry. The results are as follows: The derived standard molar enthalpies of formation of the gaseous compounds were compared with values estimated by assuming the enthalpy increment for substitution of chlorine in aniline to be the same as for substitution into benzene.     

Standard molar enthalpies of formation of lithium alkoxides

The standard (p⁰ = 0.1 MPa) molar enthalpies of formation of several crystalline lithium alkoxides, ΔH_f⁰(LiOR, cr), have been determined by reaction-solution calorimetry at 298.15 K. A linear correlation has been found between ΔH_f⁰(LiOR, cr) and ΔH_f⁰(ROH, 1) for R = n-alkyl, enabling the prediction of data for other lithium alkoxides. The deviations from the linear correlation observed for R =ⁱPr and ^tBu were tentatively explained in terms of the electronegativities of the OR groups. The experimental data were also used to derive the lattice energies and the thermochemical radii of the anions OR⁻. The results were compared with those derived from the enthalpies of formation of the analogous sodium alkoxides, reported in a previous publication.     

Standard enthalpies of formation of some N-spiranes

The heats of combustion of three compounds, members of a new series of N-spiranes were measured by combustion calorimetry. The molecules of the title compounds comprise condensed and N-spirofused heterocycles as well as nitroxy groups that are both NO-donors and explosophores. The enthalpies of formation and the heats of explosive transformation of these compounds are calculated. Two compounds belong to explosives with low heat of explosive transformation, whereas the third compound is inert.     

Standard molar enthalpies of formation of 5- and 6-nitroindazole

The present work reports the experimental determination of the standard (p ^o = 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 ring.     

Experimental standard molar enthalpies of formation of some 4-alkoxybenzoic acids

The present work is part of a research program on the energetics of the linear 4-n-alkoxybenzoic acids, aiming the study of the enthalpic effect of the introduction of an alkoxy chain in the position 4- of the benzoic acid ring. In this work, we present the results of the thermochemical research on 4-n-alkoxybenzoic acids with the alkoxy chain length n = 2, 4, and 8.The standard ($p^{°}=0.1\text{MPa}$) molar enthalpy of formation of crystalline 4-ethoxybenzoic acid, 4-butoxybenzoic acid, and 4-(octyloxy)benzoic acid was measured, at T = 298.15 K, by static-bomb calorimetry. These values, combined with the values of standard molar enthalpies of sublimation, were used to derive the standard molar enthalpies of formation in the gaseous phase.     

14.

Proton-transfer tautomerism and enthalpies of formation of some isoquinoline derivatives     

Mansoor Namazian  Michelle L. Coote 《The Journal of chemical thermodynamics》2009,(12):1446-1448

Ab initio molecular orbital theory has been used to calculate enthalpies of formation of the keto tautomers of 1-hydroxyisoquinoline, 5-hydroxyisoquinoline, and 1,5-dihydroxyisoquinoline. The high-level composite method G3//B3LYP has been used for this study, and the results have been compared with available experimental values. The keto tautomer is more favourable for 1-hydroxyisoquinoline and 1,5-dihydroxyisoquinoline, and the experimental enthalpies of formation are in better agreement with the theoretical enthalpies of formation of the keto forms.     

15.

Standard molar enthalpies of formation and of sublimation of 2-thiophenecarboxamide and 2-thiopheneacetamide     

Manuel A.V. Ribeiro da Silva  Ana Filipa L.O.M. Santos 《The Journal of chemical thermodynamics》2008,40(2):166-173

     

16.

Standard molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids     

Manuel A.V. Ribeiro da Silva  Luísa M.P.F. Amaral  Cristina R.P. Boaventura  Jos R.B. Gomes 《The Journal of chemical thermodynamics》2008,40(8):1226-1231

The standard (p = 0.1 MPa) molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids were derived from their standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation of 2- and 3-cyanobenzoic acids. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and standard molar enthalpies for phase transition. The results obtained are −(150.7 ± 2.0) kJ · mol⁻¹, −(153.6 ± 1.7) kJ · mol⁻¹ and −(157.1 ± 1.4) kJ · mol⁻¹ for 2-cyano, 3-cyano and 4-cyanobenzoic acids, respectively. Standard molar enthalpies of formation were also estimated by employing two different methodologies: one based on the Cox scheme and the other one based on several different computational approaches. The calculated values show a good agreement with the experimental values obtained in this work.     

17.

Standard molar enthalpies of formation of 2-furancarbonitrile, 2-acetylfuran,and 3-furaldehyde     

Manuel A.V. Ribeiro da Silva  Luísa M.P.F. Amaral 《The Journal of chemical thermodynamics》2009,41(1):26-29

The standard (p^° = 0.1 MPa) molar energies of combustion of 2-furancarbonitrile, 2-acetylfuran, and 3-furaldehyde were measured by static bomb combustion calorimetry; the Calvet high-temperature microcalorimetry was used to measure the enthalpies of vaporization of these liquid compounds. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the liquid phase and the standard molar enthalpies of phase transition, as (106.8 ± 1.1) kJ · mol^?1, ?(207.4 ± 1.3) kJ · mol^?1, and ?(151.9 ± 1.1) kJ · mol^?1, for 2-furancarbonitrile, 2-acetylfuran, and 3-furaldehyde, respectively.Standard molar enthalpies of formation are discussed in terms of the isomerization ortho meta. Enthalpic increment values of the introduction of the functional groups –CN, –CHO, and –COCH₃ were also compared with some other heterocycles; i.e. thiophene and pyridine.     

18.

三氯苯的标准生成焓和异构化焓     

阎海科  顾建国  安绪武  胡日恒 《化学学报》1987,45(12):1184-1187

报导了用精密转动弹量热计测定诸三氯苯燃烧热的实验结果,并计算出这些化合物在液态(或固态)和气态下的标准生成焓.同时还计算出它们的异构化焓和原子化热,并与一般公认为比较精确的热化学键能模式的计算值进行比较和讨论.     

19.

Standard molar enthalpies of formation of the methoxynitrophenol isomers: a combined experimental and theoretical investigation     

《The Journal of chemical thermodynamics》2004,36(5):431-436

In this paper we present the calorimetric determination of the standard molar enthalpies of combustion, sublimation, and formation of three methoxynitrophenol isomers: 2-methoxy-4-nitrophenol, 2-methoxy-5-nitrophenol and 4-methoxy-2-nitrophenol.In addition, density functional theory calculations with the B3LYP functional and two different atomic basis sets: 6-31G* and 6-311G** allowed the estimation of the standard molar enthalpies of formation in the gaseous phase, for all possible methoxynitrophenol isomers.The theoretical estimations are in good agreement with the experimental determined standard molar enthalpies of formation.     

20.

Standard molar enthalpies of formation of 2-, 3-, and 4-piperidinomethanol isomers     

《The Journal of chemical thermodynamics》2006,38(8):1008-1012

     

Proton-transfer tautomerism and enthalpies of formation of some isoquinoline derivatives

Ab initio molecular orbital theory has been used to calculate enthalpies of formation of the keto tautomers of 1-hydroxyisoquinoline, 5-hydroxyisoquinoline, and 1,5-dihydroxyisoquinoline. The high-level composite method G3//B3LYP has been used for this study, and the results have been compared with available experimental values. The keto tautomer is more favourable for 1-hydroxyisoquinoline and 1,5-dihydroxyisoquinoline, and the experimental enthalpies of formation are in better agreement with the theoretical enthalpies of formation of the keto forms.     

Standard molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids

The standard (p = 0.1 MPa) molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids were derived from their standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation of 2- and 3-cyanobenzoic acids. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and standard molar enthalpies for phase transition. The results obtained are −(150.7 ± 2.0) kJ · mol⁻¹, −(153.6 ± 1.7) kJ · mol⁻¹ and −(157.1 ± 1.4) kJ · mol⁻¹ for 2-cyano, 3-cyano and 4-cyanobenzoic acids, respectively. Standard molar enthalpies of formation were also estimated by employing two different methodologies: one based on the Cox scheme and the other one based on several different computational approaches. The calculated values show a good agreement with the experimental values obtained in this work.     

Standard molar enthalpies of formation of 2-furancarbonitrile, 2-acetylfuran,and 3-furaldehyde

The standard (p^° = 0.1 MPa) molar energies of combustion of 2-furancarbonitrile, 2-acetylfuran, and 3-furaldehyde were measured by static bomb combustion calorimetry; the Calvet high-temperature microcalorimetry was used to measure the enthalpies of vaporization of these liquid compounds. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the liquid phase and the standard molar enthalpies of phase transition, as (106.8 ± 1.1) kJ · mol^?1, ?(207.4 ± 1.3) kJ · mol^?1, and ?(151.9 ± 1.1) kJ · mol^?1, for 2-furancarbonitrile, 2-acetylfuran, and 3-furaldehyde, respectively.Standard molar enthalpies of formation are discussed in terms of the isomerization ortho meta. Enthalpic increment values of the introduction of the functional groups –CN, –CHO, and –COCH₃ were also compared with some other heterocycles; i.e. thiophene and pyridine.     

三氯苯的标准生成焓和异构化焓

报导了用精密转动弹量热计测定诸三氯苯燃烧热的实验结果,并计算出这些化合物在液态(或固态)和气态下的标准生成焓.同时还计算出它们的异构化焓和原子化热,并与一般公认为比较精确的热化学键能模式的计算值进行比较和讨论.     

Standard molar enthalpies of formation of the methoxynitrophenol isomers: a combined experimental and theoretical investigation

In this paper we present the calorimetric determination of the standard molar enthalpies of combustion, sublimation, and formation of three methoxynitrophenol isomers: 2-methoxy-4-nitrophenol, 2-methoxy-5-nitrophenol and 4-methoxy-2-nitrophenol.In addition, density functional theory calculations with the B3LYP functional and two different atomic basis sets: 6-31G* and 6-311G** allowed the estimation of the standard molar enthalpies of formation in the gaseous phase, for all possible methoxynitrophenol isomers.The theoretical estimations are in good agreement with the experimental determined standard molar enthalpies of formation.