Tunable Hydrophobic Eutectic Solvents Based on Terpenes and Monocarboxylic Acids
authors Martins, MAR; Crespo, EA; Pontes, PVA; Silva, LP; Bulow, M; Maximo, GJ; Batista, EAC; Held, C; Pinho, SP; Coutinho, JAP
nationality International
journal ACS SUSTAINABLE CHEMISTRY & ENGINEERING
author keywords Terpenes; Monocarboxylic acids; SLE; PC-SAFT; Solvatochromic parameters; Densities; Viscosities; Eutectic solvents
keywords DIRECTIONAL ATTRACTIVE FORCES; EQUATION-OF-STATE; PERTURBED-CHAIN SAFT; CARBOXYLIC-ACIDS; ASSOCIATING FLUIDS; IONIC LIQUIDS; TRANSDERMAL DELIVERY; PHASE-EQUILIBRIA; SKIN PERMEATION; DEEP
abstract Recently, some works claim that hydrophobic deep eutectic solvents could be prepared based on menthol and monocarboxylic acids. Despite of some promising potential applications, these systems were poorly understood, and this work addresses this issue. Here, the characterization of eutectic solvents composed of the terpenes thymol or L(-)-menthol and monocarboxylic acids is studied aiming the design of these solvents. Their solid-liquid phase diagrams were measured by differential scanning calorimetry in the whole composition range, showing that a broader composition range, and not only fixed stoichiometric proportions, can be used as solvents at low temperatures. Additionally, solvent densities and viscosities close to the eutectic compositions were measured, showing low viscosity and lower density than water. The solvatochromic parameters at the eutectic composition were also investigated aiming at better understanding their polarity. The high acidity is mainly provided by the presence of thymol in the mixture, while L(-)-menthol plays the major role on the hydrogen-bond basicity. The measured mutual solubilities with water attest to the hydrophobic character of the mixtures investigated. The experimental solid-liquid phase diagrams were described using the PC-SAFT equation of state that is shown to accurately describe the experimental data and quantify the small deviations from ideality.
publisher AMER CHEMICAL SOC
issn 2168-0485
year published 2018
volume 6
issue 7
beginning page 8836
ending page 8846
digital object identifier (doi) 10.1021/acssuschemeng.8b01203
web of science category Chemistry, Multidisciplinary; Green & Sustainable Science & Technology; Engineering, Chemical
subject category Chemistry; Science & Technology - Other Topics; Engineering
unique article identifier WOS:000444924500085

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