Modified enthalpies of formation for hydrocarbons from DFT and ab initio thermal energies

Shafagh, Ida; Hughes, Kevin J.; Pourkashanian, Mohamed

doi:10.1016/j.comptc.2010.12.005

Cited by 2 publications

(1 citation statement)

References 23 publications

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“…The authors verified that the proposed correction method resulted in more accurate values of enthalpies improving the average relative errors with respect to experimental values from 0.90% to 0.03% . Similarly, Shafagh et al . successfully applied a three-parameter equation to minimize the error in the calculations of enthalpies of formation of 50 selected hydrocarbon species using different ab initio and DFT methods.…”

Section: Introductionmentioning

confidence: 76%

Determination of Enthalpies of Formation of Fatty Acids and Esters by Density Functional Theory Calculations with an Empirical Correction

Silva

Custódio

Reis

2015

Ind. Eng. Chem. Res.

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Scarcity of reliable thermochemical data of biodiesel molecules motivated the use of computational calculations to accurately predict standard enthalpies of formation of fatty acids and esters by combining B3LYP/6-311+G(d,p) calculations with an empirical correction. This correction is based on information on the molecular structure and is optimized by using the least-squares method to minimize the deviation between theoretical and experimental enthalpies for some fatty acids and esters. The mean absolute deviation between calculated and experimental enthalpies decreased from 122.3 to 5.3 kJ mol–1 when the parametric correction equation was applied to the B3LYP/6-311+G(d,p) results for fatty acid molecules. The calculated data were used to estimate thermochemical properties of the esterification reactions of oleic and linoleic acids with methanol. Results confirmed the endothermic and the nonspontaneous characteristics of these reactions. Thus, the proposed correction is a suitable alternative to calculate thermodynamic properties of fatty acids and esters, with remarkable accuracy and low computational cost.

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Section: Introductionmentioning

confidence: 76%

Determination of Enthalpies of Formation of Fatty Acids and Esters by Density Functional Theory Calculations with an Empirical Correction

Silva

Custódio

Reis

2015

Ind. Eng. Chem. Res.

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Mechanism of α-acetyl-γ-butyrolactone synthesis

Wang¹,

Zhang

et al. 2013

Chemical Papers

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The mechanism of α-acetyl-γ-butyrolactone (ABL) synthesis from γ-butyrolactone (GBL) and ethyl acetate (EtOAc) was explored by detecting the material changes involved and the enthalpies of formation of the synthons, products, and possible intermediates were calculated using the density functional theory. GBL forms a carbanion of γ-butyrolactone by losing an α-H under strongly alkaline conditions. ABL is then obtained via two reaction mechanisms. One of the reaction mechanisms involves direct reaction of the carbanion of GBL with EtOAc to produce ABL. The other involves the formation of a carbanion of α-(2-hydroxy-tetrahydrofuran-2-yl)-γ-butyrolactone through the reaction of two molecules of GBL, and the subsequent combination of this anion with EtOAc to produce ABL. ABL is thus formed through the above two kinds of competitive ester condensation reactions. It is unnecessary to take into account synthons’ local thickness, and their self-condensation under these conditions. Both reactions of the carbanion of GBL with EtOAc and GBL are exothermic, so the control of their reaction rate is the key to their security. Considering the reasons above, this work applied synthon as the solvent, and avoided environmental pollution by alkylbenzene; also, accidents such as red material and fire were avoided by specific surface area of sodium metal control. Effective isolation of the organic and aqueous phases was performed using the salting out method. Thus, an environmentally friendly, safe, simple, and efficient new method for the synthesis of ABL with the yield higher than 90 % has been established.

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Modified enthalpies of formation for hydrocarbons from DFT and ab initio thermal energies

Cited by 2 publications

References 23 publications

Determination of Enthalpies of Formation of Fatty Acids and Esters by Density Functional Theory Calculations with an Empirical Correction

Determination of Enthalpies of Formation of Fatty Acids and Esters by Density Functional Theory Calculations with an Empirical Correction

Mechanism of α-acetyl-γ-butyrolactone synthesis

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