Dialkylimidazolium-based ionic liquids (ILs) are one of the most employed and accessible ILs. These novel chemicals possess unique physicochemical properties which, unfortunately, are greatly altered by impurities. A simple method to evaluate the purity level of ILs is proposed, as a direct relationship exists between refractive index (RI) and purity. Two multilayer perceptrons (MLPs) have been designed to estimate the RI values using the molecular weights (MWs) of the imidazolium-based ILs. The RI is defined as the single output of the created neural network models. These MLPs offered low verification prediction errors (less than 0.48% in both cases), thus leading to useful mathematical tools that are able to more than adequately estimate the RI of imidazolium-based ILs by solely relying on the MWs. Therefore, an extremely manageable mathematical tool that can accurately estimate the RIs of imidazolium-based ILs, and, in the end, their purity, has been created. Additional tests were developed with experimental data regarding two imidazolium-based ILs to evaluate the applicability of the networks, and the results were successful in terms of RI and purity estimation. 
Inputting molecular weights into a multilayer perceptron to estimate refractive indices of dialkylimidazolium-based ionic liquids—A purity evaluation