Octanol–water partition coefficients and aqueous solubility data of monoterpenoids: experimental, modeling, and environmental distribution

Terpenes and terpenoids encompass one of the most extensive and valuable classes of secondary metabolites. Their ten-carbon-containing oxygenated representatives, monoterpenoids, are the main components of plant essential oils, being widely exploited in the cosmetic, pharmaceutical, and food industrial areas. Due to its widespread use, it is crucial to investigate their environmental distribution. Thus, new water solubility data were obtained for six monoterpenoids ((1R)-(+)-camphor, (S)-(+)-carvone, eucalyptol, (1R)- (−)-fenchone, L-(−)-menthol, and (−)-menthone) at 298.2 and 313.2 K. Furthermore, octanol−water partition coefficients of 12 monoterpenoids (the six mentioned above plus carvacrol, (±)-β-citronellol, eugenol, geraniol, linalool, and thymol) were measured at 298.2 K. The COSMO-RS thermodynamic model and other more empirical approaches were evaluated for the description of the solubilities and partition coefficients, showing reliable predictions. Lastly, the distribution of the monoterpenoids in the different environmental compartments was assessed through an intuitive two-dimensional chemical space diagram based on the physicochemical equilibrium information reported.This work was developed within the scope of the project CIMO-Mountain Research Center, UIDB/00690/2020, and CICECO-Aveiro Institute of Materials, UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. S.M.V.-B. thanks FCT and the European Social Fund (ESF) for his Ph.D. grant (SFRH/BD/138149/2018). M.C.d.C. would also like to thank CNPq (306666/ 2020-0) and FAPESP (2014/21252-0).info:eu-repo/semantics/publishedVersio

The role of the anion in imidazolium-based ionic liquids for fuel and terpenes processing

Abstract: The potentialities of methylimidazolium-based ionic liquids (ILs) as solvents were evaluated for some relevant separation problems—terpene fractionation and fuel processing—studying selectivities, capacities, and solvent performance indices. The activity coefficients at infinite dilution of the solute (1) in the IL (3), g¥ 13, of 52 organic solutes were measured by inverse gas chromatography over a temperature range of 333.2–453.2 K. The selected ILs are 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6], and the equimolar mixture of [C4mim][PF6] and 1-butyl-3-methylimidazolium chloride, [C4mim]Cl. Generally, low polar solutes follow g¥ 1,[C4mim]Cl > g¥ 1,[C4mim][PF6]+[C4mim]Cl > g¥ 1,[C4mim][PF6] while the opposite behavior is observed for alcohols and water. For citrus essential oil deterpenation, the results suggest that cations with long alkyl chains, such as [C12mim]+, promote capacity, while selectivity depends on the solute polarity. Promising results were obtained for the separation of several model mixtures relevant to fuel industries using the equimolar mixture of [C4mim][PF6] and [C4mim]Cl. This work demonstrates the importance of tailoring the polarity of the solvents, suggesting the use of ILs with mixed anions as alternative solvents for the removal of aliphatic hydrocarbons and contaminants from fuels.This research was funded by the European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of Project GreenHealth—Digital strategies in biological assets to improve well-being and promote green health, Norte-01-0145-FEDER- 000042, to which A. Zambom is thankful for her grant. S. M. Vilas-Boas thanks FCT and the European Social Fund (ESF) for his Ph.D. grant (SFRH/BD/138149/2018 and COVID/BD/152936/2022). L.P.Silva acknowledges FCT for her Ph.D. grant (SFRH/BD/135976/2018).info:eu-repo/semantics/publishedVersio

Vapor pressure and thermophysical properties of eugenol and (+)-carvone

In this work, vapor pressures, liquid-phase heat capacities, and phase behavior of two monoterpenoids, (þ)-carvone and eugenol were studied. The vapor pressure experiments were performed using a static method over an environmentally relevant range of temperatures, from 258 K to 308 K. Liquid-phase heat capacities were measured by Tian-Calvet calorimetry between 265 K and 355 K. The phase behavior was investigated by heat-flux differential scanning calorimetry from 183 K. Experimental data were supplemented by ideal-gas thermodynamic properties obtained by combining quantum chemical and statistical thermodynamic calculations. Vapor pressures and heat capacities obtained in this work along with selected literature values were treated simultaneously by multi-property correlation in order to obtain a consistent description of thermodynamically linked properties. To our knowledge, liquid-phase heat capacities and phase behavior of eugenol are reported for the first time in this work.The authors M.F., K.R., V. S., and V.P. acknowledge financial support from the Czech Science Foundation (GACR no. 17-03875S) and specific university research (MSMT No. 20-SVV/2018). The authors S.M.V., O.F., and S.P.P. acknowledge financial support from the project POCI-01-0145-FEDER-006984 e Associate Laboratory LSRE-LCM (UID/EQU/50020/2019) funded by national funds through FCT/MCTES (PIDDAC). S.M.V. also acknowledges FCT for his PhD grant (SFRH/BD/138149/2018).info:eu-repo/semantics/publishedVersio

Water activity and freezing points in aqueous solutions of manganese nitrate: experimental and modeling

The water activities of manganese nitrate solutions were measured using a humidity sensor instrument up to almost the saturation molality at 298.15 K; the thermodynamic properties of the system were described by the Pitzer model and specific interaction theory (SIT). The evaluation of the ion interaction parameters for the Pitzer model and SIT were carried out using experimental freezing points and osmotic coefficients of manganese nitrate aqueous solutions, collected from the open literature, and the water activity data measured in this work. A set of Pitzer and SIT parameters were estimated using a temperature dependency, that enables us to cover wider temperature ranges, and consequently calculate system properties to higher molalities. Both approaches represent very satisfactorily, and with similar accuracy, the experimental data and the calculated manganese nitrate molal activity coefficients are comparable to those already published for analogous systems. Additionally, the Pitzer model was also able to calculate the ice curve and the solubility branch of manganese nitrate hexahydrate up to a salt solution 6.5 mol-kg-1.This work was developed in the scope of the projects POCI-01-0145-FEDER- 006984—Associate Laboratory LSRE-LCM both funded by European Regional Development Fund (ERDF) through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCT—Fundação para a Ciência e a Tecnologia. This work is also a result of project ‘‘AIProcMat@N2020—Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020’’, with the reference NORTE-01-0145-FEDER-000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through ERDF.info:eu-repo/semantics/publishedVersio

Solvent and temperature effects on the solubility of syringic, vanillic or veratric acids: Experimental, modeling and solid phase studies

The solubility of syringic acid, vanillic acid and veratric acid was measured in pure water and eleven organic solvents (methanol, ethanol, 1-propanol, 2-propanol, 2-butanone, ethyl acetate, acetonitrile, dimethylformamide, 1,2-propanediol, 1,3-propanediol and 1,3-butanediol), at 298.2 K and 313.2 K. Besides the solubility data, the melting temperatures and enthalpies of the solutes were determined by differential scanning calorimetry, while powder and single X-ray diffractionwere used to resolve the solute solid structure, before and after the solubility studies. Formodeling purposes, theNRTL-SACmodel, also combinedwith the Reference Solvent Approach (RSA), and the Abraham solvation model were applied to describe the solid-liquid equilibria of the binary systems. A set of solvents was used to estimate the model parameters and afterwards, solubility predictions were carried out for binary systems not included in the correlation step. Better results were obtained using the Abraham solvation model with average relative deviations (ARD) of 15% for the correlation set and 26% for the predictions, which are more satisfactory than the results found with the NRTL-SAC model (33% for the correlation and 59% for the predictions) or the NRTL-SAC model combined with RSA (30% for the correlation and 59% for the predictions).We acknowledge the support of the project “AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, with the reference NORTE-01-0145-FEDER- 000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); Associate Laboratory LSRE-LCM - UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC); UID/CTM/50011/2019 (CICECO), financed by national funds through the FCT/MCTES; and project AllNat - POCI-01- 0145-FEDER-030463 (PTDC/EQU-EPQ/30463/2017), financed by FEDER funds through COMPETE and Portugal2020 and national funds through FCT - Fundação para a Ciência e a Tecnologia. The authors also thank FCT for financial support to S. M. Vilas-Boas grant (SFRH/BD/138149/2018) and V. Vieira grant (SFRH/BD/108487/ 2015).info:eu-repo/semantics/publishedVersio

Solid-liquid phase equilibrium of trans-cinnamic acid, p-coumaric acid and ferulic acid in water and organic solvents: Experimental and modelling studies

The solubility of the trans isomers of cinnamic acid, p-coumaric acid and ferulic acid was measured in water and seven organic solvents (methanol, ethanol, 1-propanol, 2-propanol, 2-butanone, ethyl acetate and acetonitrile), at 298.2 K and 313.2 K, using the analytical shake-flask technique. The melting temperatures and enthalpies of the solutes were studied by differential scanning calorimetry, while solute solid structures were identified by powder and single X-ray diffraction. The NRTL-SAC model was applied to calculate the solubility of trans-cinnamic acid and trans-ferulic acid in pure solvents. For trans-p-coumaric acid, the NRTL-SAC was combined with the Reference Solvent Approach, as the solute melting properties could not be determined. The global average relative deviations (ARD) were 32% and 41%, in the correlation and prediction stages, respectively. The Abraham solvation model was also applied. The global ARD were 20% for correlation and 29% for predictions, which can be considered very satisfactory results for these semi-predictive models.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/ 50011/2020, and CIMO-Mountain Research Center, UIDB/00690/ 2020, both financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. We also acknowledge the support of the projects “AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, with the reference NORTE-01-0145-FEDER- 000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); and project AllNat - POCI-01-0145-FEDER-030463, funded by the European Regional Development Fund (ERDF) through the Competitiveness and Internationalization Operational Program (COMPETE2020-POCI) and national funding from the Foundation for Science and Technology (FCT, Portugal). S. M. Vilas-Boas thanks the financial support provided by FCT PhD grant (SFRH/BD/138149/ 2018).info:eu-repo/semantics/publishedVersio

Experimental solubility and density studies on aqueous solutions ofquaternary ammonium halides, and thermodynamic modelling formelting enthalpy estimations

Aiming to extend the yet limited knowledge on phase equilibria and physical-chemical properties of quaternaryalkylammonium halides and their aqueous binary systems, the solubilities of ten salts in water were measured inthis work in the temperature range between 293.2 K and 348.2 K along with their densities. The PC-SAFT equa-tion of state was thenapplied in the description of density as well as water activity coefficients data. The model-ling results describe very satisfactorily the experimental data, and the non-associating parameters follow well-defined trends with the molecular weight of the alkylammonium halides. These parameters were applied inthe prediction of the solubility data with unsatisfactory results, with mole fraction average absolute deviation(AAD= 0.018), deteriorating with increasing alkyl chain length.However, refitting thebinaryinteraction param-eter a much better description is obtained (AAD = 0.0045). COSMO-RS was also applied for the solubility predic-tion (AAD = 0.025), with poorer results for the chloride salts. After, the melting enthalpies of the quaternaryalkylammonium halides were estimated using the PC-SAFT equation, which in spite of their uncertainty, are pos-sibly the best option to perform solid-liquid equilibrium analysis of utmost importance when designing andscreening new deep eutectic mixtures based on these compounds.publishe

Ionic liquids as entrainers for terpenes fractionation and other relevant separation problems

This work discusses the potential of two phosphonium-based ionic liquids (ILs), [P6,6,6,14]Cl and [P6,6,6,14][(C8H17)2PO2], and one methylimidazolium-based IL, [C4mim][OAc], as entrainers in the fractionation of terpene mixtures, in the desulfurization and denitrification of fuel oils, and in the separation of aromatics from aliphatic hydrocarbons. To this aim, the activity coefficients at infinite dilution of 45 solutes were obtained by gas-chromatography in the temperature range (333.15–458.15) K. Selectivities and capacities were calculated showing that [P6,6,6,14]Cl is adequate for the fractionation of (−)-menthone/L-(−)-menthol mixture, being also a suitable option for the deterpenation of citrus essential oil, and the removal of thiophene and pyridine from aliphatic hydrocarbons. To complement the experimental measurements COSMO-RS model was tested, demonstrating good potential to screen separation agents and give insights for several important separation problems, including the removal of contaminants from fuels and the isolation, fractionation and purification of terpenes mixtures.This work was developed within the scope of the project CICECOAveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, and CIMO-Mountain Research Center, UIDB/00690/2020, both financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. Sérgio M. Vilas-Boas also thanks FCT for the Ph.D. grant (SFRH/BD/138149/2018).info:eu-repo/semantics/publishedVersio

Solubility and solid phase studies of isomeric phenolic acids in pure solvents

The solubilities of gallic, protocatechuic, gentisic or α-resorcylic acids were measured in nine pure solvents (water, methanol, ethanol, 1-propanol, 2-propanol, 2-butanone, ethyl acetate, acetonitrile and dimethylformamide) at 298.15 K and 313.15 K, using the analytical isothermal shake-flask method. Additionally, solid phase studies of the selected phenolic acids were carried out using differential scanning calorimetry (DSC) and X-ray diffraction (XRD), giving access to important data on melting properties as well as on the structure of the solid phase before and after the dissolution. The NRTL-SAC model coupled to the reference solvent approach (RSA) were applied to correlate the solubility data in a set of seven solvents and, after used to predict the solubility in 1-propanol and dimethylformamide. Average relative deviations (ARD) between 28 and 40% for the correlation and between 16 and 59% for the predictions were obtained. These values are within the order of magnitude usually found for such type of semi-predictive models, using a limited set of data.This work is supported by: Project “AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); Project POCI-01-0145-FEDER-006984 – Associate Laboratory LSRE-LCM funded by ERDF through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI); Project POCI-01-0145-FEDER-030463 financed by COMPETE and Portugal2020 and national funds through FCT - Fundação para a Ciência e a Tecnologia . We also acknowledge the support of CICECO – Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (Ref. FCT UID/CTM/50011/2013 ). Appendix Ainfo:eu-repo/semantics/publishedVersio

Comparison of two computational methods for solvent screening in countercurrent and centrifugal partition chromatography

Countercurrent and centrifugal partition chromatography are techniques applied in the separation and isolation of compounds from natural extracts. One of the key design parameters of these processes is the selection of the biphasic solvent system that provides for the adequate partitioning of the solutes. To address this challenging task, the fully predictive Conductor-like Screening Model for Real Solvents (COSMO-RS) and the semi-predictive Non-Random Two-Liquid Segment Activity Coefficient (NRTL-SAC) model were applied to estimate the partition coefficients ( K ) of four model phenolic compounds (vanillin, ferulic acid, ( S )-hesperetin and quercetin) in different solvent systems. Complementing the experimental data collected in the literature, partition coefficients of each solute in binary, or quaternary, solvent sys- tems were measured at 298.2 K. Higher deviations from the experimental data were obtained using the predictive COSMO-RS model, with an average RMSD (root-mean-square deviation) in log( K ) of 1.17 of all four solutes (61 data points), providing a satisfactory quantitative description only for the systems containing vanillin (RSMD = 0.57). For the NRTL-SAC model, the molecular parameters of the solutes were initially calculated by correlating a set of K and solubility ( x , in mole fraction) data (16 partition coefficients and 44 solubility data points), for which average RMSD values of 0.07 and 0.41 were obtained in log( K ) and log( x ) , respectively. The predictions of the remaining log( K ) data (45 partition coefficients) resulted in an average RMSD of 0.43, suggesting that the NRTL-SAC model was a more reliable quantitative solvent screening tool. Depending on the amount of available solubility and partition data, both models can be valuable alternatives in the preliminary stages of solvent screening destined to select the optimal mobile and stationary phases for a given separation.This work was developed within the scope of the project All- Nat - POCI-01–0145-FEDER-030463 (PTDC/EQU-EPQ/30463/2017), funded by FEDER funds through COMPETE2020 –Prog. Operacional Competitividade e Internacionalização (POCI), and by national funds through the Foundation for Science and Technology (FCT/MCTES). Support was also provided by CIMO-Mountain Research Center, UIDB/00690/2020 and CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, both financed by national funds through FCT/MCTES. S. M. Vilas-Boas thanks FCT and the European Social Fund (ESF) for his Ph.D. grant (SFRH/BD/138149/2018). I. W. Cordova and H. Almeida also thank project AllNat - POCI-01–0145-FEDER-030463 for their contracts.info:eu-repo/semantics/publishedVersio