A thermodynamically guided calculation of free energies of substrate and product molecules allows for the estimation of the yields of organic reactions. The non-ideality of the system and the solvent effects are taken into account through the activity coefficients calculated at the molecular level by perturbed-chain statistical associating fluid theory (PC-SAFT). The model is iteratively trained using a diverse set of reactions with yields that have been reported previously. This trained model can then estimate apriori the yields of reactions not included in the training set with an accuracy of ca. +/- 15%. This ability has the potential to translate into significant economic savings through the selection and then execution of only those reactions that can proceed in good yields