Database of Small Molecule Thermochemistry for Combustion

Abstract

High-accuracy ab initio thermochemistry is presented for 219 small molecules relevant in combustion chemistry, including many radical, biradical, and triplet species. These values are critical for accurate kinetic modeling. The RQCISD(T)/cc-PV∞QZ//B3LYP/6-311++G(d,p) method was used to compute the electronic energies. A bond additivity correction for this method has been developed to remove systematic errors in the enthalpy calculations, using the Active Thermochemical Tables as reference values. On the basis of comparison with the benchmark data, the 3σ uncertainty in the standard-state heat of formation is 0.9 kcal/mol, or within chemical accuracy. An uncertainty analysis is presented for the entropy and heat capacity. In many cases, the present values are the most accurate and comprehensive numbers available. The present work is compared to several published databases. In some cases, there are large discrepancies and errors in published databases; the present work helps to resolve these problems.

Understanding the reactivity of unsaturated alcohols: Experimental and kinetic modeling study of the pyrolysis and oxidation of 3-methyl-2-butenol and 3-methyl-3-butenol

“…Thermochemical data for molecules and radicals are taken from databases when possible [44][45][46][47], otherwise the thermodynamic functions are estimated using Benson's group additivity concept for thermochemistry [48], using recently proposed group additive values and hydrogen bond increments [41,45,46].…”

Critical Evaluation of Thermochemical Properties of C1–C4 Species: Updated Group-Contributions to Estimate Thermochemical Properties

“…Much of this data is collated in the NIST database, 1 Active Thermochemical Tables (ATcT), 2 Third Millennium Thermodynamic Database 3 and from numerous experimental and theoretical studies. A recent ab initio study by Goldsmith et al 4 reported thermochemical properties for over 200 combustion relevant species. A study by Verevkin et al 5 collected and critically evaluated experimental data for enthalpies of formation in the liquid phase, enthalpies a) Electronic mail: Author to whom correspondence should be addressed.…”

“…The thermodynamic properties of ethane have been studied extensively 4,11,[13][14][15][16][17][18][19][20][21][22] as shown in Tables I and II Tables III and IV contain literature values for the heat of formation and molar entropy of the ethyl radical. As with most of the species included in this study there are more values available for the heat of formation (Table III) compared to the molar entropy (Table IV).…”

“…3,4,11,13,14,17,21,22,27 The values are included in Tables V and VI. The average of the literature heat of formation values for propane is −24.94 kcal mol −1 with a standard deviation of 0.12 kcal mol −1 . The value from Goldsmith et al …”

“…The heat of formation and molar entropy for 1-propenyl radical has been reported in a limited number of studies 4,17,58,59 and values are included in Tables XXXI and XXXII. Further studies are needed to acquire a more accurate estimate of the uncertainty for these parame- …”