10.1021/acs.iecr.8b01249.s001 Emanuel A. Crespo Emanuel A. Crespo Liliana P. Silva Liliana P. Silva Mónia A. R. Martins Mónia A. R. Martins Mark Bülow Mark Bülow Olga Ferreira Olga Ferreira Gabriele Sadowski Gabriele Sadowski Christoph Held Christoph Held Simão P. Pinho Simão P. Pinho João A. P. Coutinho João A. P. Coutinho The Role of Polyfunctionality in the Formation of [Ch]Cl-Carboxylic Acid-Based Deep Eutectic Solvents American Chemical Society 2018 HBD HBA eutectic points coordinates eutectic mixtures DES acid modeling interaction nonideality Ch PC-SAFT phase diagrams monofunctional hydrogen-bond donors SLE 2018-07-19 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/The_Role_of_Polyfunctionality_in_the_Formation_of_Ch_Cl-Carboxylic_Acid-Based_Deep_Eutectic_Solvents/6900968 Aiming at providing an extensive characterization of the solid–liquid equilibria (SLE) of deep eutectic solvents (DESs), the phase diagrams of nine eutectic mixtures composed of choline chloride ([Ch]­Cl) and (poly)­carboxylic acids, commonly reported in the literature as DESs, were measured experimentally. Contrarily to the behavior reported for eutectic mixtures composed of [Ch]Cl (hydrogen-bond acceptor, HBA) and monofunctional hydrogen-bond donors (HBD) such as fatty acids and fatty alcohols, which have recently been shown to be almost ideal mixtures, a significant decrease of the melting temperature, at the eutectic point, was observed for most of the systems studied. This melting temperature depression was attributed to a pronounced nonideality of the liquid phase induced by the strong hydrogen-bond interactions between the two mixture components. Perturbed-chain statistical associating fluid theory (PC-SAFT) was used to describe these interactions physically. PC-SAFT allowed accurately modeling the experimental phase diagrams over the entire concentration and temperature ranges. Depending on the kind of mixture, up to two temperature-independent binary interaction parameters between HBA and HBD were applied. The PC-SAFT approach was used to provide trustworthy information on the nonideality of the liquid phase (expressed as the activity coefficients of HBA and HBD) as well as to estimate the eutectic points coordinates. The experimental data along with the modeling results allowed us to infer about the importance of the HBD’s chemical structure on the formation of [Ch]­Cl-based DESs.