Molecular Surface Description of Halomethanes and its Relation to Their Physicochemical Properties: A Quantum Chemical Investigation

Abstract

The relation between a compound’s molecular surface and its respective macroscopic properties is a particularly intriguing field of quantitative structure-property relationship (QSPR) studies. More specifically, physicochemical properties like critical volumes Vc and critical pressures Pc are, undoubtedly, amongst the important characteristics for chemical research and chemical industries. Besides, the acentric factor ω has been proven efficacious for a sufficient characterization of fluids. In the present work, we offer a new approach to the determination of the mentioned properties of halomethanes from computed molecular surface properties assisted by a simple atomic contribution. The molecular surfaces of the halomethanes were first studied in terms of their molecular electrostatic potential (MEP) maps and average local ionization energy (ALIE) maps, in addition to their molecular surfaces’ areas and volumes. Certain molecular surface properties were calculated and employed as independent variables in a multiple linear regression (MLR) analysis against Vc, Pc and ω. For Vc, MLR based on two variables resulted in a correlation coefficient R = 0.996 and a relative standard error RSE = 2.68%. For Pc, using two additional independent variables, R and RSE were found to be 0.980 and 4.48%. Finally, for ω, using one more independent variable, R and RSE were found to be 0.978 and 5.79%, respectively. This was a quite good improvement of Vc prediction and a very substantial improvement of Pc prediction, compared to results obtained by applying variables from previous literature to the same halomethanes under study. Moreover, the prediction of the acentric factor from quantum-chemical calculation is unprecedented in literature.