Owing to the significance in kinetic modeling of the oxidation and combustion mechanisms of hydrocar- bons, a fast and relatively accurate method was developed for the prediction of DfH o of alkyl peroxides. By this method, a raw DfH o value was calculated from the optimized geometry and vibration frequencies at B3LYP/6- 31G(d,p) level and then an accurate DfH o value was obtained by a least-square procedure. The least-square proce- dure is a six-parameter linear equation and is validated by a leave-one out technique, giving a cross-validation squared correlation coefficient q 2 of 0.97 and a squared correlation coefficient of 0.98 for the final model. Calculated results demonstrated that the least-square calibration leads to a remarkable reduction of error and to the accurate DfH o values within the chemical accuracy of 8 kJ mol 21 except (CH3)2CHCH2CH2CH2OOH which has an error of 8.69 kJ mol 21 . Comparison of the results by CBS-Q, CBS-QB3, G2, and G3 revealed that B3LYP/6-31G(d,p) in combination with a least-square calibration is reliable in the accurate prediction of the standard enthalpies of forma- tion for alkyl peroxides. Standard entropies at 298 K and heat capacities in the temperature range of 300-1500 K for alkyl peroxides were also calculated using the rigid rotor-harmonic oscillator approximation.
['Cun‐Xi Liu', 'Ze-Rong Li', 'Chong-Wen Zhou', 'Xiang-Yuan Li']
Accurate prediction of thermodynamic properties of alkyl peroxides by combining density functional theory calculation with least‐square calibration