Enthalpy of Combustion on n‐Alkanes. Quantum Chemical Calculations up to n‐C60H122 and Power Law Distributions

Audran, Gérard; Marque, Sylvain R. A.; Siri, Didier; Santelli, Maurice

doi:10.1002/slct.201802021

Cited by 13 publications

(20 citation statements)

References 33 publications

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“…The main support for this functional form comes from the linear behavior of a log−log plot. 13 As the authors commented, the exponent in the power law form is a little larger than 2 for all the studied groups of molecules, β > 2. 14 The linear trend found in the molecular energy, eq 1, leads to a natural algebraic form for δ E , and it is given by eq 4.…”

mentioning

confidence: 89%

“…In some cases, a linear behavior is also followed by the gas-phase enthalpy and free energy. , This observation comes for the larger magnitude of the molecular energy with respect to the thermal contributions to the gas-phase thermodynamic quantities and the linear trend from those contributions for these linear chains.…”

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confidence: 96%

“…However, the numerical results from Audran et al show that the thermal terms do not alter the linearity coming from the molecular energy, at least in the set of studied compounds. 13,14 This issue also deserves more attention in the future.…”

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confidence: 99%

“…Recently, Audran et al analyzed the difference between the energy per unit of two consecutive linear chains, eq . , …”

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confidence: 99%

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Comment on “Power Law Distribution Concerning Absolute Free Energies of Linear Sulfur Chains, Polythiazyls, Polyisoprenes, Linear trans-Polyenes, and Polyynes”

Cedillo

2019

J. Phys. Chem. A

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Recently, an analysis of some linear molecular chains showed that the molecular energy grows as a linear function of the number of fragments in molecules of the form A−B n −C, where A, B, and C are chemical fragments. Additionally, the difference in the energy per fragment of two consecutive molecular chains was fitted into a power law form showing similar exponents close to 2. In this contribution, a natural expression, different from the power law, is presented for the previously mentioned difference.

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confidence: 89%

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confidence: 96%

mentioning

confidence: 99%

“…Recently, Audran et al analyzed the difference between the energy per unit of two consecutive linear chains, eq . , …”

mentioning

confidence: 99%

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Comment on “Power Law Distribution Concerning Absolute Free Energies of Linear Sulfur Chains, Polythiazyls, Polyisoprenes, Linear trans-Polyenes, and Polyynes”

Cedillo

2019

J. Phys. Chem. A

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“…Although they have not reported the accuracy of their theoretically calculated combustion enthalpies in comparison with the experimental data, their theoretically reported values demonstrate significant deviations compared to experiment, as we show in table 3 below. Audran and co-workers [12] employed ab-initio computations to calculate combustion enthalpies using four different levels of theory. They reported significant deviations between the predicted and experimental data and proposed linear relationships to empirically improve the theoretically evaluated combustion enthalpies.…”

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confidence: 99%

High precision evaluation of the combustion enthalpy by ab-intio computations

Alibakhshi¹

2021

Preprint

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Accurate evaluation of combustion enthalpy is of high scientific and industrial importance. Although via ab-initio computation of heat of reactions, as one of the promising and well-established approaches in computational chemistry, this goal should in principle be achievable, examples of reliable and precise evaluation of heat of combustion by ab-initio methods has surprisingly not yet been reported. A handful of works carried out for this purpose report significant inconsistencies between the ab-initio evaluated and experimentally determined combustion enthalpies and suggest empirical corrections to improve the accuracy of predicted data. With this background, the main aims of the present study is to investigate the reasons behind those reported inconsistencies and propose guidelines for highly accurate evaluation of combustion enthalpy via ab-initio computations. Through the provided guidelines, the most accurate results ever reported, with average absolute deviation, mean unsigned error and correlation coefficient of 1.556 kJ/mole, 0.072% and 0.99999, respectively, is achieved for theoretically computed combustion enthalpies of 40 studied hydrocarbons.

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Oligomers. Relations between their computed free energies

et al. 2023

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Free energies G(X)n of 12 1,ω‐dihydrooligomers (X)n (n, number of the monomeric units) have been determined by quantum calculations. We note that these values are correlated by (a) an excellent linear relationship: G(X)n = An – 761.86 ± 10 (kcal mol–1) (TPSS‐TPSS/6.311 + + G(dp)); (b) for two oligomers (X)n and (Y)n, the difference of weighted free energies—G(X)n/n – G(Y)n/n—is a constant irrespective of n which results from the difference of free energies of the substituent. Consequently, from the Gn values of 1,ω‐dihydrooligoethenes (in fact n‐alkanes), a determination of the free energies of a 1,ω‐dihydrooligomers (X)n is obtained with a good accuracy by the calculation of the G value of its substituent; (c) the corresponding increments G(X)n/n – G(X)(n–1)/(n–1) are equaled and led to a single power law: [Gn/n – G(n–1)/(n–1) = 1282/n2.156 (kcal mol–1), R = 0.9992] or a linear relationship: [Gn/n – G(n–1)/(n–1) = 756.73/n(n–1) + 0.0211 (kcal mol–1), R = 1]. Syndiotactic and isotactic 1,ω‐dihydrooligomers (X) are illustrated in the Electronic Supporting Information.

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Enthalpy of Combustion on n‐Alkanes. Quantum Chemical Calculations up to n‐C₆₀H₁₂₂ and Power Law Distributions

Cited by 13 publications

References 33 publications

Comment on “Power Law Distribution Concerning Absolute Free Energies of Linear Sulfur Chains, Polythiazyls, Polyisoprenes, Linear trans-Polyenes, and Polyynes”

Comment on “Power Law Distribution Concerning Absolute Free Energies of Linear Sulfur Chains, Polythiazyls, Polyisoprenes, Linear trans-Polyenes, and Polyynes”

High precision evaluation of the combustion enthalpy by ab-intio computations

Oligomers. Relations between their computed free energies

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