Determination modified enthalpy of formation of straight alkyl-chained carboxylic acids and esters

The Corrected Values of ΔrHo(CaHbOd, a≤16) of Atomization of the Aromatic Compounds and Their Uncertainties Determined Using Several Quantum Mechanical Approaches

“…The values of SE Y and SE YE <3 kJ/mol, determined in the present work for the considered PAH are also consistent with the accuracy, reported for others organic compounds [20–24] . However, in many of these cases, the not straightforward three parameters scaling dependencies are used for determination of the standard enthalpies of formation of the smaller and not aromatic compounds.…”

“…The values of SE Y and SE YE < 3 kJ/mol, determined in the present work for the considered PAH are also consistent with the accuracy, reported for others organic compounds. [20][21][22][23][24] However, in many of these cases, the not straightforward three parameters scaling dependencies are used for determination of the standard enthalpies of formation of the smaller and not aromatic compounds. The using of scaling (calibration) dependencies, determined for the different small sized organic compounds, in the case of composite methods, such as CBS-4M, CBS-Q, CBS-QB3, is probably also the main reason why the values of (SE 4 ) 4 and (SE 4 ) 9 , determined in the present work, are smaller those values, determined for the CBS-QB3 approach (i = 13).…”

Structures and Energetics of Unimolecular Thermal Degradation of Isopropyl Butanoate as a Model Biofuel: Density Functional Theory and Ab Initio Studies

“…Some experimental and few theoretical studies have been reported for real biofuel. − Direct studies of typical biodiesels are difficult because experiments would have to be carried out on complex, largely involatile mixtures and also because of the computational cost needed for such large molecules. However, better understanding of the combustion mechanism can be accomplished using a model biofuel.…”

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

“…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%. 14 Similarly, Shafagh et al 15 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. Duan et al 16 also proposed a correction using linear regression in order to account for the effects of electron correlation neglected by the Hartree−Fock theory and to reduce systematic errors of the B3LYP functional.…”

“…The method, called DFT-Neuron, resulted in a decrease in the average error from 89.7 to 13.0 kJ mol –1 and from 50.3 to 13.8 kJ mol –1 using the B3LYP/6-311+G­(d,p) and the B3LYP/6-311+G­(3df,2p) models, respectively . Liu and Cheng calculated enthalpies of formation of a group of 35 molecules of carboxylic acids and esters using the B3LYP and the Hartree–Fock levels of theory, both with the 4-31G­(d) basis set. In order to obtain accurate enthalpies of formation, Liu and Cheng proposed a correction using a parametric fitting, where parameters were based on the numbers of carbon and hydrogen atoms of the molecule.…”