ChemInform Abstract: Resonance Energy Calculation; the MM2ERW Force Field

Roth, Wolfgang R.; Adamczak, Oliver; Breuckmann, Rolf; Lennartz, Hans‐Werner; Boese, Roland

doi:10.1002/chin.199202066

Cited by 3 publications

(6 citation statements)

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“…The most obvious example is 1,3-cyclopentadiene where the ATcT value of Δ f H ⊖ (298.15K) = 101.30 ± 2.5 differs considerably from our result of 137.1 ± 6.7 kJ mol –1 . In the compendium Thermochemical Data of Organic Compounds, Pedley et al quote a value of 134.3 ± 1.5 kJ mol –1 , whereas the NIST WebBook includes determinations , of 139 and 133.4 kJ mol –1 . In a thermochemical and kinetic analysis of addition reactions to 1,3-cyclopentadiene Zhong and Bozzelli use a value of 131 kJ mol –1 .…”

Section: Resultsmentioning

confidence: 99%

Benchmarking Compound Methods (CBS-QB3, CBS-APNO, G3, G4, W1BD) against the Active Thermochemical Tables: A Litmus Test for Cost-Effective Molecular Formation Enthalpies

2015

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The theoretical atomization energies of some 45 CxHyOz molecules present in the Active Thermochemical Tables compilation and of particular interest to the combustion chemistry community have been computed using five composite model chemistries as titled. The species contain between 1-8 "heavy" atoms, and a few are conformationally diverse with up to nine conformers. The enthalpies of formation at 0 and 298.15 K are then derived via the atomization method and compared against the recommended values. In general, there is very good agreement between our averaged computed values and those in the ATcT; those for 1,3-cyclopentadiene exceptionally differ considerably, and we show from isodesmic reactions that the true value for 1,3-cyclopentadiene is closer to 134 kJ mol(-1) than the reported 101 kJ mol(-1). If one is restricted to using a single method, statistical measures indicate that the best methods are in the rank order G3 ≈ G4 > W1BD > CBS-APNO > CBS-QB3. The CBS-x methods do on average predict ΔfH(⊖)(298.15 K) within ≈5 kJ mol(-1) but are prone to occasional lapses. There are statistical advantages to be gained from using a number of methods in tandem, and all possible combinations have been tested. We find that the average formation enthalpy coming from using CBS-APNO/G4, CBS-APNO/G3, and G3/G4 show lower mean signed and mean unsigned errors, and lower standard and root-mean-squared deviations, than any of these methods in isolation. Combining these methods also leads to the added benefit of providing an uncertainty rooted in the chemical species under investigation. In general, CBS-APNO and W1BD tend to underestimate the formation enthalpies of target species, whereas CBS-QB3, G3, and G4 have a tendency to overestimate the same. Thus, combining CBS-APNO with a G3/G4 combination leads to an improvement in all statistical measures of accuracy and precision, predicting the ATcT values to within 0.14 ± 4.21 kJ mol(-1), thus rivalling "chemical accuracy" (±4.184 kJ mol(-1)) without the excessive cost associated with higher-level methods such as W1BD.

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Section: Resultsmentioning

confidence: 99%

Benchmarking Compound Methods (CBS-QB3, CBS-APNO, G3, G4, W1BD) against the Active Thermochemical Tables: A Litmus Test for Cost-Effective Molecular Formation Enthalpies

2015

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“…27−29 Turner and co-workers 30−32 in an extensive series about three decades ago measured the enthalpies of hydrogenation for different classes of compounds. These systematic studies have been continued in more recent times through the extensive work of Roth and co-workers 33,34 and by Rogers and coworkers. 35−38 A summary of enthalpies of hydrogenation is given by Jensen.…”

Section: ■ Introductionmentioning

confidence: 98%

“…For data derived from experiment, much of the quantitative knowledge regarding the stability of PAHs is influenced in a number of ways by the work of Kistiakowsky and co-workers in the 1930s who examined the enthalpies of hydrogenation of a variety of unsaturated compounds. − Turner and co-workers − in an extensive series about three decades ago measured the enthalpies of hydrogenation for different classes of compounds. These systematic studies have been continued in more recent times through the extensive work of Roth and co-workers , and by Rogers and co-workers. − A summary of enthalpies of hydrogenation is given by Jensen …”

Section: Introductionmentioning

confidence: 99%

“…Thermochemical functions for cyclic hydrocarbons and cyclopentadiene derivatives have been provided by Dorofeeva et al , and Karni et al, respectively. Of extreme value is the extensive compilation of enthalpies of hydrogenation for unsaturated molecules including PAHs that is given in the widely cited work by Roth et al…”

Section: Introductionmentioning

confidence: 99%

“…Thermochemical functions for cyclic hydrocarbons and cyclopentadiene derivatives have been provided by Dorofeeva et al 51,52 and Karni et al, 53 respectively. Of extreme value is the extensive compilation of enthalpies of hydrogenation for unsaturated molecules including PAHs that is given in the widely cited work by Roth et al 33 Chickos et al have provided an extensive compilation of experimental enthalpies of vaporization and sublimation 54,55 for a wide range of compounds and have developed group additivity based methods for estimating enthalpies of vaporization and sublimation. 56,57 Sabbah et al 58 have reviewed experimental data and methods for determining enthalpies of vaporization and sublimation.…”

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

First-Principles Prediction of Enthalpies of Formation for Polycyclic Aromatic Hydrocarbons and Derivatives

Allison

Burgess

2015

J. Phys. Chem. A

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In this article, the first-principles prediction of enthalpies of formation is demonstrated for 669 polycyclic aromatic hydrocarbon (PAH) compounds and a number of related functionalized molecules. It is shown that by extrapolating density functional theory calculations to a large basis set limit and then applying a group based correction scheme that good results may be obtained. Specifically, a mean unsigned deviation and root mean squared deviation from the experimental enthalpies of formation data of 5.0 and 6.4 kJ/mol, respectively, are obtained using this scheme. This computational scheme is economical to compute and straightforward to apply, while yielding results of reasonable reliability. The results are also compared for a smaller set of molecules to the predictions given by the G3B3 and G3MP2B3 variants of the Gaussian-3 model chemistry with a mean unsigned deviation and root mean squared deviation from the experimental enthalpies of formation of 4.5 and 4.8 kJ/mol, respectively.

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First Ring Formation by Radical Addition of Propargyl to But-1-ene-3-yne in Combustion. Theoretical Study of the C₇H₇Radical System

et al. 2014

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Combustive formation of a first carbon ring is an important step in the growth of polycyclic aromatic hydrocarbons (PAHs) and soot platelets. Propargyl radical addition to but-1-ene-3-yne (vinylacetylene) can start this process, possibly forming 5-, 6-, and 7-membered rings. A variety of partially intertwined reaction pathways results from density functional theory (DFT), which indicates three C7H7 radicals, benzyl, tropyl, and vinylcyclopentadienyl, as particularly stable. DFT energetics forms a basis for a subsequent Rice-Ramsperger-Kassel-Marcus (RRKM) study at different combustion pressures and temperatures (P = 30-0.01 atm; T = 1200-2400 K). RRKM indicates open-chain structures and 5-rings as the most important products. Open-chain structures, whose main contributors are the initial adducts, are favored by lower T and higher P, while 5-rings are favored by higher T and lower P. The main feature is that the declining yield in open-chain structures with rising T almost mirrors, at all pressures, the growth with T exhibited by 5-rings (main contributor: fulvenallene). Thus, the two yield lines for open chains and 5-rings cross at some T, and their crossing moves toward lower T values as lower P values are considered. Because the T dependence of the yields (slope of the lines) is more pronounced in the T range close to the line crossing, it also becomes less pronounced at the lowest P values considered because the crossing region falls at very low T values. Another constant trait is that 6-rings (mainly benzyl radical) are the third contributor, though they are present at most with a modest maximum yield of 2.4-2.7% in a T range which moves toward lower T as P is reduced.

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ChemInform Abstract: Resonance Energy Calculation; the MM2ERW Force Field

Cited by 3 publications

References 1 publication

Benchmarking Compound Methods (CBS-QB3, CBS-APNO, G3, G4, W1BD) against the Active Thermochemical Tables: A Litmus Test for Cost-Effective Molecular Formation Enthalpies

Benchmarking Compound Methods (CBS-QB3, CBS-APNO, G3, G4, W1BD) against the Active Thermochemical Tables: A Litmus Test for Cost-Effective Molecular Formation Enthalpies

First-Principles Prediction of Enthalpies of Formation for Polycyclic Aromatic Hydrocarbons and Derivatives

First Ring Formation by Radical Addition of Propargyl to But-1-ene-3-yne in Combustion. Theoretical Study of the C₇H₇Radical System

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ChemInform Abstract: Resonance Energy Calculation; the MM2ERW Force Field

Cited by 3 publications

References 1 publication

Benchmarking Compound Methods (CBS-QB3, CBS-APNO, G3, G4, W1BD) against the Active Thermochemical Tables: A Litmus Test for Cost-Effective Molecular Formation Enthalpies

Benchmarking Compound Methods (CBS-QB3, CBS-APNO, G3, G4, W1BD) against the Active Thermochemical Tables: A Litmus Test for Cost-Effective Molecular Formation Enthalpies

First-Principles Prediction of Enthalpies of Formation for Polycyclic Aromatic Hydrocarbons and Derivatives

First Ring Formation by Radical Addition of Propargyl to But-1-ene-3-yne in Combustion. Theoretical Study of the C7H7Radical System

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First Ring Formation by Radical Addition of Propargyl to But-1-ene-3-yne in Combustion. Theoretical Study of the C₇H₇Radical System