Extension of the Constantinou and Gani group contribution method with the Tochigi method through an automatic conversion procedure

Group contribution methods (GCMs) are widely employed across various disciplines to estimate compound properties when experimental data is lacking in the literature. While several methods exist, none are comprehensive, as they exhibit gaps either in functional groups or the predicted properties or simply do not offer the required accuracy. As a result, different methods may be necessary to evaluate distinct properties of the same compound. Typically, switching between these models is performed manually due to variations in the sets of functional groups employed. However, with the advancements in computational power and numerical optimum search, there is a growing need to automate the conversion between different group contribution methods. This study presents a procedure to extend the property estimation of the Constantinou and Gani method with vapor pressure by supplementing it with the Tochigi method using an automated group conversion algorithm. The difficulties of automatic conversion procedures, resulting from the differences in the group sets and the shortcomings of the GCMs, are also highlighted. It is also demonstrated that the accuracy of the acentric factor estimation can only be refined to a limited extent by incorporating the Tochigi method, which is, however, indispensable for the several groups where the Constantinou and Gani group contribution values are missing.