SIMPOL.1: a simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

摘要

The SIMPOL.1 group contribution method is developed forpredicting the liquid vapor pressure (atm) andenthalpy of vaporization Δ H (kJ mol) oforganic compounds as functions of temperature (). For each compound , themethod assumes log ()=∑ν() where ν is thenumber of groups of type , and () is the contribution to log () by each group of type . A zeroeth group isincluded that uses () with ν=1 for all . A total of30 structural groups are considered: molecular carbon, alkyl hydroxyl,aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde,ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary,secondary, and tertiary), aromatic amine, amide (primary, secondary, andtertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate,nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C–C=O ina non-aromatic ring, and carbon on the acid-side of an amide. The dependence in each of the () is assumed to follow ()=/+++ln . Values of the coefficients are fit using an initial basis set of 272 compounds for which experimentally basedfunctions = () are available. The range of vapor pressureconsidered spans fourteen orders of magnitude. The ability of the initiallyfitted coefficients to predict values is examinedusing a test set of 184 compounds and a range that is as wide as 273.15 to393.15 K for some compounds. σ is defined as the average overall points of the absolute value of the difference between experimental andpredicted values of log (). Afterconsideration of σ for the test set, the initial basis setand test set compounds are combined, and the coefficients re-optimized. Forall compounds and temperatures, σ=0.34: on average, () values are predicted to within a factor of 2.Because (log ())(1/) is related to theenthalpy of vaporization Δ, the fitted providepredictions of Δ based on structure.