Classifying Structural Characteristics to Enhance Computation of Enthalpy of Formation of Halohydrocarbons

Abstract

Density functional theory (DFT) calculations are made and least squares calibration performed for various halohydrocabons, which were 27 straight-chain alkyl halides, 20 branch-chain alkyl halides and 19 aromatic halides, to determine their enthalpies of formation (DH f ). The mean absolute error (M. |A.E.|) in DH f across 66 molecular computations was only 7.8 kJ/mol (1.9 kcal/mol). Grouping the molecules by their structural characteristics improved M. |A.E.| of DH f by 0.2-2.2 kJ/mol over that obtained using corresponding modified data for the same 66 unclassified molecules.