Modified calculations of hydrocarbon thermodynamic properties

Abstract

A test set of 65 hydrocarbons was examined to elucidate theoretically their thermodynamic properties by performing the density-functional theory (DFT) and ab initio calculations. All the calculated data were modified using a three-parameter calibration equation and the least-squares approach, to determine accurately enthalpies of formation (DeltaH(f)), entropies (S), and heat capacities (C(p)). Calculation results demonstrated that the atomization energies of all compounds exhibited an average absolute relative error ranging between 0.11- 0.13%, and an DeltaH(f) of formation with a mean absolute absolute error (M.|A.E.|) ranging from only 5.7-6.8 kJ/mol (1.3-1.6 kcal/mol) (i.e., those results correlated with those of Dr. Herndon's 1.1 kcal/mol). Additionally, the entropy ranged from 3.5-4.2 J/mol K (0.8-1.0 cal/mol K) M.|A.E.|; a heat capacity between 2.3-2.9 J/mol K (0.5-0.7 cal/mol K) M.|A.E.| was obtained as well.

Comparative simulation study of chemical synthesis of energetic (R)‐1,2,4‐butanetriol trinitrate plasticizer

“…The bond lengths and vibrational frequencies of optimized (R)‐BTTN (Figure ) were compared with those obtained from the literature, revealing very close numerical results. Furthermore, the five‐parametric equation‐calibrated gaseous formation enthalpy and formation free energy, liquid phase formation enthalpy and B3LYP/6‐31G(d,p)‐computed constant pressure heat capacity were also close to the values contained in chemical databases (Table ). The relative errors were between 0.09 and 3.55%, which indicated a high reliability of the research methods employed.…”

Conceptual, Qualitative, and Quantitative Theories of 1,3‐Dipolar and Diels–Alder Cycloadditions Used in Synthesis

“…[75] However, does DFT, especially the popular B3LYP, give experimentally accurate kinetic and thermodynamic energies? Recently, many investigations have been devoted to testing the performance of DFT methods for bond dissociation energies, [76] enthalpies of formation, [77] enthalpies of atomization, [78] proton affinities, [79] hydrogen abstraction reactions, [80] radical reactions, [81] weak interactions, [82] S N 2 reactions, [83] pericyclic reactions, [84,85] organic reactions, [86,87] metals, [88] materials, [89] biological applications, and even reactions relevant to astrophysics. [90] This section reviews investigations that give the most reliable quantitative thermochemistries for Diels-Alder and 1,3-dipolar cycloadditions.…”

Accurate prediction of thermodynamic properties of alkyl peroxides by combining density functional theory calculation with least‐square calibration

“…Another model for estimation of the enthalpy of formation is the empirical models, such as QSPR model24 and group additive (GA) model,25–28 which can be adopted to estimate the approximate values for large molecules. Recently, a model combining the quantum chemical calculation with QSPR correction was proposed to improve the enthalpies of formation calculated by high level or low level quantum chemical methods 29–36. The general assumption behind this model is that the deviations of the calculated results by a quantum chemical method from the experiment results for different molecules have the same relative tendency and can be calibrated with statistical approach.…”