Recently, many studies concerning the environmental impact of ionic liquids (ILs) have shown that despite their unique properties and clear advantages in an ever wide range of applications and processes, ILs are not intrinsically green. In a search for biodegradable and low toxicity, a new type of ILs has been developed, the deep eutectic solvents (DESs). In this context, the aim of this work is to provide accurate densities, viscosities, and refractive indices for DESs prepared using cholinium chloride as the hydrogen bond acceptor and several carboxylic acids (levulinic, glutaric, malonic, oxalic, and glycolic) as the hydrogen bond donors. The impact of two different synthetic methodologies, heating and grinding, in the thermophysical properties of the prepared DESs was assessed. The obtained DESs were analyzed using NMR spectroscopy, FTIR, and electrospray ionization mass spectrometry in order to check their structures and purities. Thermophysical properties, densities, viscosities, and refractive indices were rationalized in terms of the chemical structure of the prepared DESs. The effect of the presence of water in the thermophysical properties of the compounds was also evaluated. Finally, comparisons between the DESs and the corresponding ILs are presented.

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The ionic nature of ionic liquids (ILs) results in a unique combination of intrinsic properties that produces increasing interest in the research of these fluids as environmentally friendly "neoteric" solvents. One of the main research fields is their exploitation as solvents for liquid-liquid extractions, but although ILs cannot vaporize leading to air pollution, they present non-negligible miscibility with water that may be the cause of some environmental aquatic risks. It is thus important to know the mutual solubilities between ILs and water before their industrial applications. In this work, the mutual solubilities of hydrophobic yet hygroscopic imidazolium-, pyridinium-, pyrrolidinium-, and piperidinium-based ILs in combination with the anions bis-(trifluoromethylsulfonyl)imide, hexafluorophosphate, and tricyanomethane with water were measured between 288.15 and 318.15 K. The effect of the ILs structural combinations, as well as the influence of several factors, namely cation side alkyl chain length, the number of cation substitutions, the cation family, and the anion identity in these mutual solubilities are analyzed and discussed. The hydrophobicity of the anions increases in the order [C(CN) 3 ] < [PF 6 ] < [Tf 2 N] while the hydrophobicity of the cations increases from [C n mim] < [C n mpy] e [C n mpyr] < [C n mpip] and with the alkyl chain length increase. From experimental measurements of the temperature dependence of ionic liquid solubilities in water, the thermodynamic molar functions of solution, such as Gibbs energy, enthalpy, and entropy at infinite dilution were determined, showing that the solubility of these ILs in water is entropically driven and that the anion solvation at the IL-rich phase controls their solubilities in water. The COSMO-RS, a predictive method based on unimolecular quantum chemistry calculations, was also evaluated for the description of the water-IL binary systems studied, where it showed to be capable of providing an acceptable qualitative agreement with the experimental data.

Controversy behind the postulation that ionic liquids (ILs) are entirely green materials emerged a few years ago. This statement is not always valid, and properties such as toxicity and chemical/thermal stability of ILs should be fully characterized to evaluate their potential use as green solvents. Therefore, in this work, the thermal and chemical decompositions of hexafluorophosphate- and tetrafluoroborate-based ILs in aqueous solutions were evaluated. The experimental conditions employed allowed the study of the possible decomposition of both anions, the effect of the cation side alkyl chain length, the influence of the pH of the aqueous solutions, as well as the temperature influence. Three experimental techniques were employed to fully characterize those anions' stability, electrospray mass spectrometry, nuclear magnetic resonance spectroscopy, and pH measurements of the equilibrium aqueous solutions. The results noticeably indicate that it is suitable to use aqueous solutions of hexafluorophosphate-based ILs at moderate temperatures while acidic conditions promote the anion hydrolysis, even at low temperatures. On the other hand, the tetrafluoroborate-based ILs are not water-stable compounds since they hydrolyze under all of the conditions tested and the hydrolysis extent is markedly dependent on the temperature.

This paper explores a period of substantial variation in trade policy across industries in Colombia (1977Colombia ( -1991 to examine whether increased exposure to foreign competition generates productivity gains for manufacturing plants. Using an estimation methodology that addresses the shortcomings of previous studies, we find a strong positive impact of tariff liberalization on plant productivity, even after controlling for plant and industry heterogeneity, real exchange rates, and cyclical effects. The impact of liberalization is stronger for larger plants and plants in less competitive industries. Our findings are not driven by the endogeneity of protection. Similar results are obtained when using effective rates of protection and import penetration ratios as measures of protection. Productivity gains under trade liberalization are linked to increases in intermediate inputs' imports, skill intensity, and machinery investments, and to output reallocations from less to more productive plants.