PARÂMETROS QUÍMICO-FÍSICOS DE TERPENOS E TERPENOIDES PARA APLICAÇÃO EM ESTUDOS DE IMPACTO AMBIENTAL

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Publications

Measurements of activity coefficients at infinite dilution of organic solutes and water on polar imidazolium-based ionic liquids

Publication . Martins, Mónia A.R.; Coutinho, João A.P.; Pinho, Simão; Domańska, Urszula

The activity coefficients at infinite dilution, gamma(infinity)(13), of 55 organic solutes and water in three ionic liquids with the common cation 1-butyl-3-methylimidazolium and the polar anions Cl--,Cl- [CH3SO3](-) and [(CH3)(2)PO4](-), were determined by (gas + liquid) chromatography at four temperatures in the range (358.15 to 388.15) K for alcohols and water, and T = (398.15 to 428.15) K for the other organic solutes including alkanes, cycloalkanes, alkenes, cycloalkenes, alkynes, ketones, ethers, cyclic ethers, aromatic hydrocarbons, esters, butyraldehyde, acetonitrile, pyridine, 1-nitropropane and thiophene. From the experimental gamma(infinity)(13) values, the partial molar excess Gibbs free energy, (G) over bar (E infinity)(m), enthalpy (H) over bar (E infinity)(m), and entropy (S) over bar (E infinity)(m), at infinite dilution, were estimated in order to provide more information about the interactions between the solutes and the ILs. Moreover, densities were measured and (gas + liquid) partition coefficients (KL) calculated. Selectivities at infinite dilution for some separation problems such as octane/benzene, cyclohexane/benzene and cyclohexane/thiophene were calculated using the measured gamma(infinity)(13), and compared with literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and other ionic liquids with a common cation or anion of the ILs here studied. From the obtained infinite dilution selectivities and capacities, it can be concluded that the ILs studied may replace conventional entrainers applied for the separation processes of aliphatic/aromatic hydrocarbons.

2015Journal article

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Impact of the cation symmetry on the mutual solubilities between water and imidazolium-based ionic liquids

Publication . Martins, Mónia A.R.; Neves, Catarina M.S.S.; Kurnia, Kiki A.; Luís, Andreia; Santos, Luís M.N.B.F.; Freire, Mara G.; Pinho, Simão; Coutinho, João A.P.

Aiming at the evaluation of the impact of the ionic liquids (ILs) cation symmetry on their phase behaviour, in this work, novel mutual solubilities with water of the symmetric series of [C(n)C(n)im][NTf2] (with n=1-5) were determined and compared with their isomeric forms of the asymmetric [C(n)C(1)im][NTf2] group. While the solubility of isomeric ILs in water was found to be similar, the solubility of water in ILs follows the same trend up to a maximum cation alkyl side chain length. For n >= 4 in [C(n)C(n)im][NTf2] the solubility of water in the asymmetric ILs is slightly higher than that observed in the symmetric counterparts. The thermodynamic properties of solution and solvation derived from the experimental solubility data of ILs in water at infinite dilution, namely the Gibbs energy, enthalpy and entropy were used to evaluate the cation symmetry effect on the ILs solvation. It is shown that the solubility of ILs in water is entropically driven and highly influenced by the cation size. Accordingly, it was found that the ILs solubility in water of both symmetric and asymmetric series depends on their molecular volume. Based on these findings, a linear correlation between the logarithm of the solubility of ILs in water and their molar volume is here proposed for the [NTf2]-based ILs at a fixed temperature.

2014Journal article

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Indirect assessment of the fusion properties of choline chloride from solid-liquid equilibria data

Publication . Fernandez, Luis; Silva, Liliana P.; Martins, Mónia A.R.; Ferreira, Olga; Ortega, Juan; Pinho, Simão; Coutinho, João A.P.

The temperature and enthalpy of fusion of choline chloride -[Ch]Cl- are not directly measurable since this compound decomposes upon melting. Yet, given the wide use of this compound in the preparation of deep eutectic solvents (DES), its thermophysical fusion properties are very important for a better understanding of these mixtures and the thermodynamic description of their solid-liquid phase diagrams. In this work, the fusion properties of choline chloride were estimated using the solubility curves of choline chloride in ten different ionic compounds, forming simple binary eutectic mixtures with quasi-ideal liquid phases. Experimental solid-liquid equilibria data for these systems -[Ch] Cl + ionic compounds- were measured, and the ideality of the systems assessed through the quantification of the activity coefficients and their comparison in each pair of binary solutions. The values estimated for the fusion properties of choline chloride are T fus,[Ch]Cl = 597 ± 7 K and Δ fus H [Ch]Cl = 4300 ± 600 J mol −1 . These were additionally checked by thermodynamic consistency tests and by the prediction of the solid-liquid curves with COSMO-RS model. The results obtained with both procedures allow us to guarantee the usefulness and robustness of the estimated data.

2017Journal article

Open access

Terpenes solubility in water and their environmental distribution

Publication . Martins, Mónia A.R.; Silva, Liliana P.; Ferreira, Olga; Schröder, Bernd; Coutinho, João A.P.; Pinho, Simão

Terpenes and terpenoids belong to the largest and most diverse class of natural products. Due to the increasing importance of their applications and the emerging perception of their impact on the environment, the available physico-chemical characterization is insufficient. In this work the water solubility of geraniol, linalool, DL-citronellol, thymol, eugenol, carvacrol and p-cymene, in the temperature range from (298.15 to 323.15) K, and at atmospheric pressure, is studied. Due to the low solubility of these compounds a novel technique was adopted for their measurements and validated using the aqueous solubility data for sparingly soluble aromatic compounds. The thermodynamic properties of solution were derived from the experimental data at infinite dilution. It is shown that the solubility of terpenes in water is an endothermic process confirming the existence of UCST phase diagrams, and only for carvacrol and eugenol is entropically driven. The experimental information is shown in a two-dimensional chemical space diagram providing indications to their probable distribution in the environment once released.

2017Journal article

Open access

Aqueous solubilities of five N-(diethylaminothiocarbonyl)benzimido derivatives at T = 298.15 K

Publication . Schröder, Bernd; Martins, Mónia A.R.; Coutinho, João A.P.; Pinho, Simão

N-(diethylaminothiocarbonyl)benzimido derivatives are polar multifunctional substances. A set of these compounds was synthesised by successive substitution on the enamine side, resulting in similar substances with different polarities, providing a set of model compounds with respect to the study of substituent effects on physico-chemical properties. Experimental aqueous solubility data, at T = 298.15 K, of N-(diethylaminothiocarbonyl)benzamidine, PhCNH2NCSNEt2 (1),N-(diethylaminothiocarbonyl)-N'-phenylbenzamidine, PhCNHPhNCSNEt2 (2), N-(diethylaminothiocarbonyl)-N'-monoethylbenzamidine, PhCNHEtNCSNEt2 (3), N-(diethylaminothiocarbonyl)-N',N'-diethylbenzamidine, PhCNEt2NCSNEt2 (4), and N-(diethylaminothiocarbonyl)benzimido ethylester, PhCOEtNCSNEt2 (5) were measured at T = 298.15 K. The obtained data are supplemented by COSMO-RS aqueous solubility predictions as well as other environmentally important partition coefficients. This information is shown in a two-dimensional chemical space diagram, providing indications about the compartment into which the bulk of the compounds is likely to concentrate. The expected quality of COSMO-RS predictions for this type of screening exercise is illustrated on a set of pesticides with established thermophysical property data.

2016Journal article

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