Group Contribution Revisited: The Enthalpy of Formation of Organic Compounds with “Chemical Accuracy” Part II

Group contribution (GC) methods to predict thermochemical properties are eminently important process design. We present a group parametrization for the heat of formation organic molecules exhibiting chemical accuracy, maximum 1 kcal/mol (4.2 kJ/mol) difference between experiment and model values while minimizing number parameters avoiding overfitting therewith reduced predictability. Compared contemporary literature, this was successfully achieved by employing available literature high-quality consistent experimental data, optimizing group, introducing additional when understanding obtained supporting these. A further result is observation that applicability approach breaks down with increasing substitution levels, i.e., more heavily alkyl-substituted molecules, reason being serious influence on conformation flexible part entire molecule within particular valence angles torsional affected, which cannot be accounted GC fixed numerical values.