In this work, choline chloride/urea (1:2), choline chloride/oxalic acid (1:1), choline chloride/ethylene glycol (1:2), benzyltriphenylphosphonium chloride/ethylene glycol (1:11), tetrabutylammonium bromide/ethylene glycol (1:4), tetrabutylammonium bromide/diethylene glycol (1:4), and tetrabutylammonium bromide/triethylene glycol (1:4) were examined as deep eutectic solvents (DESs). The melting points and dynamic viscosities of these solvents were determined, and the solubilities of benzene, toluene, and ethylbenzene in each were assessed using the cloud point method between T = 303.15 and 353.15 K at atmospheric pressure. The solubilities of each of these three aromatic compounds in these DESs were found to increase with increases in temperature. Both the hydrogen bond acceptors and hydrogen bond donors in the DESs were also shown to affect solubility, with the former having a greater effect and this effect decreasing in the order of tetrabutylammonium bromide > benzyltriphenylphosphonium chloride > choline chloride. The simplified dual-parameter equation and the Apelblat empirical equation were used to correlate the experimentally determined solubilities of benzene, toluene, and ethylbenzene in the seven DESs, and the latter equation generated higher correlations.

The solubility of theobromine and theophylline in seven pure imidazolium-based ionic liquids, including 1-butyl-3methylimidazolium tetrafluoroborate ([C 4 mim]BF 4 ), 1-butyl-3methylimidazolium hexafluorophosphate ([C 4 mim]PF 6 ), 1-butyl-3-methylimidazolium nitrate ([C 4 mim]NO 3 ), 1-hexyl-3-methylimidazolium tetrafluoroborate ([C 6 mim]BF 4 ), 1-hexyl-3-methylimidazolium hexafluorophosphate ([C 6 mim]PF 6 ), 1-hexyl-3-methylimidazolium nitrate ([C 6 mim]NO 3 ), and 1-octyl-3-methylimidazolium tetrafluoroborate ([C 8 mim]BF 4 ), were measured via a static method combined with high-performance liquid chromatography between T = 303.15−353.15 K at atmospheric pressure. The solubility of theobromine and theophylline in the selected ionic liquids increased as the temperature increased. Both cations and anions in the ionic liquids affected the solubility, but anions had a more pronounced effect than the cations with a trend of NO 3 − > BF 4 − > PF 6 − . The simplified dual-parameter equation, the Apelblat empirical equation, and the λh equation were used to correlate the experimentally determined solubility of theobromine and theophylline in the investigated ionic liquids and exhibited good agreement.

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