Comparative Assessment of Group Contribution Models for Estimating the Isobaric Heat Capacity of Ionic Liquids

Eight widely used group-contribution models were evaluated for their ability to estimate the isobaric heat capacity (Cp) of ionic liquids (ILs). A curated database containing 9037 experimental data points for 142 ILs, covering eight cation families, temperatures from 190 to 524.87 K, and heat capacities from 93.0 to 1805.7 J·mol–1·K–1, was assembled to assess model performance under diverse conditions. Three main evaluation criteria were applied: predictive accuracy, functional-group flexibility, and ability to represent structural diversity of cation–anion combinations. Among the evaluated models, “GAR”, “SOR”, and “MIA” exhibited the best predictive accuracy, with overall % AARD values of 5.10%, 4.30%, and 4.22%, respectively. The “MIA” model is particularly suitable for imidazolium- and pyridinium-based ILs, relevant in industrial contexts. The “SAT” model also proved promising for CAMD applications due to its flexible atomic-contribution framework. Overall, the study offers practical guidance for selecting group-contribution methods when experimental data are unavailable.