Generalized Model to Estimate the Refractive Indices of Deep Eutectic Solvents

Reports on deep eutectic solvents (DESs), as a new category of green media following ionic liquids (ILs), are increasingly emerging in the literature. Because of the dramatically large number of DESs that will be introduced in the future, it would require much time and expense to experimentally measure their refractive indices. Therefore, proposing a global model that has the ability to estimate the refractive indices of various types of DESs is vital. In this study, it was the goal to develop an accurate, global, simple, and easy-to-use model for estimating the refractive indices of large numbers of DESs having different natures. With this idea in mind, a large up-to-date data bank for DESs was collected, consisting of 1203 data points from 153 different DESs, to develop the model. The proposed model requires critical pressure, molecular weight, and acentric factor as the input parameters. These parameters are calculated by suggested procedures. Therefore, in essence, to be used, the refractive index model does not need any experimental data. The overall absolute average relative deviation, AARD%, of the proposed model for all of the investigated DESs is 1.03%, which indicates high accuracy, as well as generality, for the estimation of the refractive indices of DESs.