Potential functions of internal rotation in n-alkanes and its contribution to thermodynamic properties

Туровцев, В. В.; Orlov, Yu. D.; Kizin, A. N.; Lebedev, Yu. A.

doi:10.1134/s1070363207090137

Cited by 7 publications

(5 citation statements)

References 41 publications

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“…The method relies on the knowledge of the contributions of representative groups in the molecule(s), usually obtained from smaller molecules, and their established linear consistency in thermochemical property contribution. A significant number of molecular properties such as molar volume, molar refraction, refractive index, and magnetic susceptibility along with thermodynamic properties such as entropy, molar heat capacity, and heat of formation can be accurately approximated as the sum of the individual groups. − Group additivity for the thermochemical properties of biofuel molecules and intermediates will be needed for use in engineering models, with the increasing importance of biofuels in our energy supply.…”

Section: Resultsmentioning

confidence: 99%

“…A significant number of molecular properties such as molar volume, molar refraction, refractive index, and magnetic susceptibility along with thermodynamic properties such as entropy, molar heat capacity, and heat of formation can be accurately approximated as the sum of the individual groups. [84][85][86][87] Group additivity for the thermochemical properties of biofuel molecules and intermediates will be needed for use in engineering models, with the increasing importance of biofuels in our energy supply.…”

Section: Cy(occ[ochmentioning

confidence: 99%

See 1 more Smart Citation

Structure and Thermochemical Properties of 2-Methoxyfuran, 3-Methoxyfuran, and Their Carbon-Centered Radicals Using Computational Chemistry

Hudzik

Bozzelli

2010

J. Phys. Chem. A

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Methoxyfurans are known components in a number of biofuel synthesis processes and their thermochemical properties are important to the stability, reaction paths, and chemical kinetics of these species. Enthalpies (DeltaH degrees (f298)), entropies (S degrees (298)), and heat capacities (C(p)(T)) are reported for 2-methoxyfuran and 3-methoxyfuran, cyclic ethers with possible biofuel implications, and their radicals corresponding to loss of hydrogen atoms. Standard enthalpies of formation are calculated at the B3LYP/6-31G(d,p), B3LYP/6-311G(2d,2p), CBS-QB3, G3MP2B3, and G3 levels of theory with isodesmic reactions to minimize calculation errors. Structures, vibrational frequencies, and internal rotor potentials are calculated at the B3LYP/6-31G(d,p) density functional level and are used to determine the entropy and heat capacities. The recommended ideal gas phase enthalpy of formation, from the average of the CBS-QB3 and G3MP2B3 levels of theory, for 2-methoxyfuran is -45.0 kcal mol(-1) and for 3-methoxyfuran is -41.1 kcal mol(-1). Bond dissociation energies are also calculated. The C-H bonds of the furan ring are approximately 120 kcal mol(-1), which is consistent with recent data on several alkylfurans; they are significantly stronger than non-aromatic, stable heterocyclic structures. The bond energy decreases to 98 kcal mol(-1) for the methoxy-methyl C-H bonds making this methyl site a favorable abstraction target and an important site for initial decomposition paths during combustion. Group additivity for furan is discussed and groups for furan and methoxyfuran carbon radicals are derived.

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Section: Resultsmentioning

confidence: 99%

Section: Cy(occ[ochmentioning

confidence: 99%

Structure and Thermochemical Properties of 2-Methoxyfuran, 3-Methoxyfuran, and Their Carbon-Centered Radicals Using Computational Chemistry

Hudzik

Bozzelli

2010

J. Phys. Chem. A

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“…Several experimental and theoretical efforts have been carried out to explain the nature of the rotational barriers and are still being investigated [26][27][28][29][30][31][32][33][34][35].…”

Section: Methodsmentioning

confidence: 99%

Exploring the G3 method in the study of rotational barrier of some simple molecules

Ducati

Custódio

Rittner

2010

Int J of Quantum Chemistry

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The G3 method was used to determine the internal rotation barriers of some simple molecules (H 2 O 2 , H 2 S 2 , N 2 H 4 , CH 3 OH, CH 3 NH 2 , and C 2 H 6 ). The barriers were accurate with deviations lower than 0.5 kcal mol À1 with respect to the experimental data and comparable with other methods like CCSD(T)/aug-cc-pVTZ results. The G3 components showed that the MP4/6-31G(d) energy is quantitatively improved according to: DE G3Large > DE 2df,p > DE þ > DE QCI . However, the relative energies showed that molecules containing lone pairs in neighbor atoms presented high barriers, which were particularly sensitive to polarization and diffuse functions. The G3Large and QCI effects showed no qualitative or quantitative relative contribution. Molecules containing lone pairs in one atom or only bond pairs presented low barriers and were sensitive not only to the polarization and diffuse effects but also depending on the improvement of the basis set through the G3Large correction. The QCI effect showed no qualitative or quantitative relevant contribution in any of the cases studied.

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“…The torsional modes were assumed as hindered motions using the Troe's formalism ; however, only the torsion about CH 2 ─CH 2 Cl bond in the molecule and in the transition state were considered. That is because the potential energy functions of internal rotations around the rest of C─C bonds are very similar in both species . Therefore, the internal rotational partition functions for those internal motions approximately cancel between the molecule and the transition state.…”

Section: Resultsmentioning

confidence: 93%

Thermochemistry and Kinetics of the Thermal Decomposition of 1‐Chlorohexane

Quinonez

Tucceri

2017

Int J of Chemical Kinetics

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A theoretical kinetic study of the thermal decomposition of 1‐chlorohexane in gas phase between 600 and 1000 K was performed. Transition‐state theory and unimolecular reaction rate theory were combined with molecular information provided by quantum chemical calculations. Particularly, the B3LYP, BMK, M05–2X, and M06–2X formulations of the density functional theory (DFT) and the high‐level ab initio methods G3B3 and G4 were employed. The possible reaction channels for the thermal decomposition of 1‐chlorohexane were investigated, and the reaction takes place through the elimination of HCl with the formation of 1‐hexene. The derived high‐pressure limit rate coefficients are k∞(600–1000 K) = (8 ± 5) × 1013 exp[‐((56.7 ± 0.4) kcal mol−1/RT)] s−1. The pressure effect over the reaction was analyzed from the calculation of the low‐pressure limit rate coefficients and the falloff curves. In addition, the standard enthalpies of formation at 298 K of −46.9 ± 1.5 kcal mol−1 for 1‐chlorohexane and 5.8 ± 1.5 kcal mol−1 for C6H13 radical were derived from isodesmic and isogiric reactions at high levels of theory.

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Potential functions of internal rotation in n-alkanes and its contribution to thermodynamic properties

Cited by 7 publications

References 41 publications

Structure and Thermochemical Properties of 2-Methoxyfuran, 3-Methoxyfuran, and Their Carbon-Centered Radicals Using Computational Chemistry

Structure and Thermochemical Properties of 2-Methoxyfuran, 3-Methoxyfuran, and Their Carbon-Centered Radicals Using Computational Chemistry

Exploring the G3 method in the study of rotational barrier of some simple molecules

Thermochemistry and Kinetics of the Thermal Decomposition of 1‐Chlorohexane

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