Model equations for estimating sublimation enthalpies of organic compounds

A recent predictive scheme aimed at estimating sublimation enthalpies is further investigated. First, the definition of the descriptors is modified in order to avoid the need for ab initio calculations. This allows us to carry out extensive testing of the approach. On the basis of simple physical arguments and experimental evidence, a new analytic representation is put forward. Both equations show a significant average absolute error of 16 kJ/mol for 55 molecules outside the calibration set. For the new equation, the errors are attributed mainly to a poor description of electrostatics.