On the composition and isomerism effect in the thermal and structural properties of choline chloride/hydroxyphenol deep eutectic solvents.

We have carried out a comparative study on three sets of eutectic mixtures based on choline chloride (ChCl) and hydroxyphenol isomers having two hydroxyl groups in the -, -, and -positions of the aromatic ring, namely catechol (Cate), resorcinol (Reso), and hydroquinone (Hydro), respectively. Differential scanning calorimetry highlighted a different thermal behavior of the mixtures depending on the composition and precursor isomerism. These systems behave as deep eutectic solvents (DESs) with the exception of the ChCl/Cate mixture at a 1 : 0.