Conductor-like Screening Model For Real Solvents Research Articles

Theoretical study of physicochemical properties of selected ammonium salt-based deep eutectic solvents

Binary deep eutectic solvents (DESs) were computationally (in-silico) designed by combining three quaternary ammonium salts, namely tetramethylammonium chloride (TMAC), choline chlorine (ChCl) and betaine as hydrogen-bond acceptors (HBAs) with sorbitol, glycerol, urea, ethylene glycol, glucose, acetic-acid, caffeic acid and 1,2-butanediol as hydrogen-bond donors (HBDs). The chosen components are among the most that were reported in the literature. Preparation of DESs with high stability relies on the interaction mechanisms between the HBAs and HBDs within the DES. In this work, interaction energies were calculated by means of COnductor-like Screening MOdel for Real Solvents (COSMO-RS) theory, which was also used to calculate σ–profiles and σ–potentials. The charge density, Fukui indices, reactivity and combination mechanisms were predicted using Dmol3 module (Materials Studio) for each component and the resulting DESs.COSMOthermX functions were used in calculating the physicochemical properties of the designed DESs. Comparison of the calculated properties is expected to provide satisfactory information about the stability and performance of the chosen deep eutectic solvents. In general, there was a relatively good agreement between the predicted values of physicochemical properties and those reported in the literature.

Selection rules for estimating the solubility of C4-hydrocarbons in imidazolium ionic liquids determined by machine-learning tools

Solubilities of C4-hydrocarbons, 1,3-butadiene (13BD), trans/cis-2-butene (T2B and C2B), 1-butene (1B), isobutene (i-But), isobutane (i-B), and butane (B), in 3267 different imidazolium-type ionic liquids (ILs) in a temperature range from 273.15 to 373.15 K were estimated by means of the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) calculations. Simple temperature-dependent mathematical expressions were developed to predict the solubility of 13BD, C2B, T2B, 1B, i-But, i-B, and B at any temperature in a range from 273 to 373 K. The COSMO-RS results for each hydrocarbon considered were then analyzed using machine learning tools, including association rule mining and decision tree classification, using semi-empirically derived molecular descriptors of ILs. It was found that the polarizabilities of both cation and anion, together with the anion's CPK (space filling model) area, are the most important descriptors for determining the affinity of ILs towards C4-hydrocarbons. Results also present the selection rules for imidazolium ILs, offering opportunities for the rational design of new ILs by using these simply-determined structural descriptors to meet the desired solubility (or selectivity) requirements for each C4-hydrocarbon considered.

Investigating the solubility of chlorophenols in hydrophobic ionic liquids

Chlorophenols (CPs) are synthetic chemicals that are generated and used widely by different industries such as textile, pharmaceutical, metallurgic, oil, and pulp and paper manufacturing. Except water, most of the solvents used in these industries are volatile and toxic. Therefore, there is an imminent need for replacing these solvents by solvents that have less negative impact on the environment. In addition, CPs are considered as hazardous pollutants due to their resistance to biodegradation and persistence in the environment. Their toxic effects are severe including DNA damage, endocrine disruption, cytotoxicity, mutagenicity, and carcinogenicity. Hence, the water contaminated by CPs must be treated before being released to the environment. Ionic liquids (ILs) are molten salts that are liquid below 100 °C, which have been used as solvents for many processes including liquid-liquid extraction and as electrolytes in electrochemical devices. ILs are characterized by negligible vapor pressure and non-flammability. These compounds are liquid over a wide range of temperatures; possess high thermal and chemical stability. ILs are being used as media for many reactions to reduce the negative impact of traditional solvents on the environment. In addition, using ILs as green solvents in water treatment has become a research hotspot. Solubility data of CPs in ILs is important for assessing the potential use of ILs as reaction media and in water treatment, but relevant data for ILs are scarce. To our best knowledge, no solubility data of chlorophenols in ILs were reported in the literature. Thus, in this study, the solubility of 3-chlorophenol (3-CP), 2,5-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP) in six hydrophobic bis(trifluoromethylsulfonyl)imide based ILs at 25 °C, 35 °C and 45 °C was investigated. It was found that the solubility of 3-CP in all studied ILs at 25 °C was greater than 70 wt%, thus the solubility measurements of 3-chlorophenol in the studied IL were stopped at 70 wt% and further measurement was not conducted. The solubility of other CPs in all studied ILs decreased with increasing the number of chlorine atoms in the CP and increased with the increase in temperature, but the degree of increase depended on the structure of both the IL and chlorinated phenol. In general, it was found that the tested chlorophenols have substantial solubility in pyridinium and imidazolium-based ILs. In addition, the non-random two-liquid model (NRTL) and Conductor-like Screening Model for Real Solvents (COSMO-RS) models were applied to predict the solubility of chlorophenols in all ILs used in this study. There was a good quantitative and qualitative agreement between experimental and calculated solubility data in most of the cases.

Calculation of drug-polymer mixing enthalpy as a new screening method of precipitation inhibitors for supersaturating pharmaceutical formulations

Supersaturating formulations are widely used to improve the oral bioavailability of poorly soluble drugs. However, supersaturated solutions are thermodynamically unstable and such formulations often must include a precipitation inhibitor (PI) to sustain the increased concentrations to ensure that sufficient absorption will take place from the gastrointestinal tract. Recent advances in understanding the importance of drug-polymer interaction for successful precipitation inhibition have been encouraging. However, there still exists a gap in how this newfound understanding can be applied to improve the efficiency of PI screening and selection, which is still largely carried out with trial and error-based approaches. The aim of this study was to demonstrate how drug-polymer mixing enthalpy, calculated with the Conductor like Screening Model for Real Solvents (COSMO-RS), can be used as a parameter to select the most efficient precipitation inhibitors, and thus realize the most successful supersaturating formulations. This approach was tested for three different Biopharmaceutical Classification System (BCS) II compounds: dipyridamole, fenofibrate and glibenclamide, formulated with the supersaturating formulation, mesoporous silica. For all three compounds, precipitation was evident in mesoporous silica formulations without a precipitation inhibitor. Of the nine precipitation inhibitors studied, there was a strong positive correlation between the drug-polymer mixing enthalpy and the overall formulation performance, as measured by the area under the concentration-time curve in in vitro dissolution experiments. The data suggest that a rank-order based approach using calculated drug-polymer mixing enthalpy can be reliably used to select precipitation inhibitors for a more focused screening. Such an approach improves efficiency of precipitation inhibitor selection, whilst also improving the likelihood that the most optimal formulation will be realized.

Theoretical investigation of the solubility of some antiemetic drugs

A theoretical study using density functional theory (DFT) is carried out to compare and explain the observed solubility of four antiemetic molecules, namely chlorpromazine, haloperidol, ondansetron and metoclopramide. The COSMO-RS (conductor-like screening model for real solvents) method is used to study the interaction between hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) of the antiemetic drugs, and their molecular interactions with water (dipole moments, interaction and solvation energies). In addition, the AIM (Atoms in Molecules) method is used to deeply study the hydrogen bonding interaction of the antiemetic drug which was found the most soluble in water, namely the metoclopramide. In fact, results show that atom O42 makes two H-bonds with two different water-oxygen atoms (BCP59 and BCP60). One of them, have another H-bond (BCP62) with the hydrogen H27. This study confirms that two of the three H-bonds with water are more stable than the intramolecular interaction between O9 and H27 (BCP1). These H-bonds are likely responsible of the highest solubility of metoclopramide.

Unraveling the effect of sub-cooling temperatures on the kinetic performance of biopolymers for methane hydrate

In deep sea plays, where the driving force or sub-cooling temperature for hydrate formation is high, the commercially used kinetic hydrate inhibitors (KHIs) lose their kinetic inhibition performance, additionally they are toxic. Though, biodegradable biopolymers are deliberated as an alternative KHIs. However, the inhibition performance of biopolymers solely for methane hydrate formation at high sub-cooling temperatures has not been evaluated. In current work the kinetic inhibition performance of five biopolymers (Pectin, Sodium- Carboxymethyl cellulose (Na-CMC), Tapioca starch, Dextran and Xanthan gum) on methane hydrate formation is evaluated using isochoric constant cooling method on sapphire hydrate reactor at 95 bar and sub-cooling temperatures of 9 °C and 12 °C. Induction time, hydrate formation rate, amount of methane consumed and percentage relative inhibition power are determined and used as kinetic inhibition indicators. Present data-set reveals that biopolymers efficiently inhibit methane hydrate formation at high sub-cooling temperatures. Among all studied biopolymers Pectin and Na-CMC commendably delayed hydrate nucleation for 78 and 61min respectively. Furthermore, Tapioca starch, Pectin and Na-CMC significantly reduced hydrate formation rate, methane consumption and percentage relative inhibition power. For further analysis on molecular level Conductor like Screening Model for Real Solvents (COSMO-RS) software is used. The interaction energy estimation using COSMO-RS showed that attractive interactions between biopolymers and water molecules are leading to prolonged nucleation. Furthermore, the effect of biopolymer concentrations (0.12 wt% - 1.5 wt%) on kinetic inhibition is elaborated by establishing a relationship between induction time, air-liquid interfacial and electrokinetic properties.

Extraction of aromas from Pistacia lentiscus L. leaves using alternative solvents: COSMO-RS-assisted solvent screening and GC-MS metabolites profiling

ABSTRACTThis study aimed to evaluate the extraction efficiency of six alternative solvents compared to hexane, conventionally used, for extraction of aromas from herbs and spices. It has been performed through theoretical approach using conductor-like screening model for real solvents (COSMO-RS) as predictive method and experimental approach based on gas chromatography–mass spectrometry (GC-MS) analysis paired with multivariate statistical analysis. Differences between theory and experiments have been noticed for cyclopentyl methyl ether (CPME) that appeared a good candidate in theory but gives the lowest extraction yield (14.12 g/L). Ethyl acetate (EtOAc) exhibited the highest extraction yield (18.74 g/L) and could be the most promising solvent to substitute hexane for aromas extraction from Pistacia. lentiscus L. leaves.

Molecular design of mass-separating agents for separation of cyclic ethers and acetonitrile from water

The conductor-like screening model for realistic solvation (COSMO-RS) and molecular dynamics simulation were used to evaluate the salting-out capacity of piperazine-containing Good's buffers (GBs) on the removal of 1,4-dioxane, 1,3-dioxolane, and acetonitrile from water. The general formula of piperazine-based GBs is 2-[4-(2-hydroxyethyl)piperazin-1-yl]alkanesulfonic acid, HO − (CH2)2 − N<CH2CH2CH2CH2 > NH+ − (CH2)n − SO3−, (n = 1–10). The buffers with n = 1 to 4 are commercially available, while the buffers with n = 5 to 10 are molecular designed in order to predict their salting-out effects on the organic solvent + water systems. The isobaric vapor-liquid equilibria of the ternary piperazine-based GB + organic solvent + water systems were predicted. The studied organic solvents are miscible with water at any composition under ambient condition and form a minimum boiling azeotropes. It was observed that the piperazine-based GBs are able to shift the azeotropic composition. The activity coefficients of water and organic solvents in presence of piperazine-based GBs were predicted using the COSMO-RS model. The influence of alkyl chain length between the zwitterion end groups on the phase behavior of the ternary systems was evaluated. Piperazine-based GBs have displayed potent mass-separating agents in the recovery of 1,4-dioxane, 1,3-dioxolane, or acetonitrile from water. The hydrogen bonds formation in MSA + organic solvent + water mixture was analyzed using molecular dynamics simulation.

Screening of Suitable Ionic Liquids as Green Solvents for Extraction of Eicosapentaenoic Acid (EPA) from Microalgae Biomass Using COSMO-RS Model.

Omega-3 poly unsaturated fatty acids (PUFA) particularly eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), have many health benefits including reducing the risk of cancer and cardiovascular disease. Recently, the use of ionic liquids (ILs) in lipid extraction from microalgae provides the potential to overcome common drawbacks, offers several other benefits. To date, very limited researches are available to focus on extracting microalgae lipid and PUFA in particular by using ILs. The objective of current work is to screen the potential ILs that can be applied in EPA extraction. In this study, fast ILs screening was performed with the help of a conductor like screening model for real solvents (COSMO-RS) and the ILs with higher capacity values for use in extraction of EPA were compared. According to the results, the highest capacity for EPA extraction among 352 screened cation/anion combinations belongs to [TMAm][SO4]. It is expected to achieve a higher yield of EPA once applying this combination as the solvent in the process of extraction. ILs with small anions were observed to have higher capacities, as well possessing higher charge density compared to larger ones, and therefore, they are more preferable for extraction purposes. Moreover, shorter alkyl chain cations are preferred when using imidazolium-based IL, which agrees with experimental data.

Thermodynamic properties of infinitely diluted solutions of organic solutes in in silico designed task-specific ionic liquid

New experimental infinite dilution activity coefficients (IDACs) of 45 different molecular solutes (alkanes, cycloalkanes, alkenes, alkynes, aromatics, alcohols, ethers, ketones, thiophene, acetonitrile, pyridine and 1-nitropropane) in the novel ionic liquid 1-(3-cyanopropyl)-1-methyl pyrrolidinium thiocyanate are presented. The considered IL has been in silico designed in our previous work by using empirical group contribution method for IDAC calculation. The experimental results shown in this paper are discussed in terms of the strength and the chemical nature of mutual interactions between the IL and the molecular solutes. An effect of nitrile group is elucidated by means of comparison of the measured data with those reported in the literature for non-functionalized counterpart of the studied IL. Furthermore, an impact of the studied “task-specific” cation on the infinite dilution selectivity in thiophene/n-octane separation problem is highlighted. The entire data set presented herein is analyzed using linear solvation-energy relationship (LSER), regular solution theory and conductor-like screening model for real solvents (COSMO-RS).

Pistacia lentiscusL. edible oil: green extraction with bio-based solvents, metabolite profiling andin vitroanti-inflammatory activity

This study assesses, qualitatively and quantitatively, the performance of ten bio-based solvents to replace hexane for the extraction of oil fromPistacia lentiscusedible fruits. Solvent screening was achieved through theoretical approach using the COnductor-like Screening MOdel for Realistic Solvation (COSMO-RS) predictions and an experimental protocol based on GC-FID and HPTLC analysis. Unsupervised multivariate analyses were performed on GC-FID and HPTLC data. Experiments corroborated theoretical predictions indicating that MeTHF was the best alternative solvent to replace hexane. Moreover, the obtained extract exhibited a good anti-inflammatory activity, inhibiting by 91.9% NO release in RAW 264.7 macrophages. These findings highlighted the potential of green solvents especially MeTHF in lipid extraction and exhibited thatP. lentiscusoil presents a potential anti-inflammatory property and great nutritional value, notably high amount of oleic and linoleic acid, thus encouraging its valorization in food, cosmetic or pharmaceutical industry.

Chemosensor Development of Cu2+ Recognition Using 1,5-Diphenylthiocarbazone: Optimization, COSMO-RS and DFT Studies

The sensitive and selective chemosensor for copper (II) ions (Cu2+) was successfully optimized using the 1,5-diphenylthiocarbazone (DPT) compound. Results showed that Dimethyl Sulfoxide (DMSO) in a 9:1 ratio with a co-solvent at a pH 3 was the optimum condition for DPT to act as chemosensor of Cu2+ recognition. The DPT chemosensor did not encounter any interference from other metal ions, including Fe3+, Ag+, Cr3+, Pb2+, Cu2+, Mg2+, Cd2+, Zn2+, K+, Ni2+ and Co2+ . The presence of Cu2+ led to an absorption peak at 658 nm, where the colour changed from cantaloupe to grey-green color indicating the interaction by the formation of the DPT-Cu complex in 2:1 stoichiometry. The theoretical σ-profile calculation using conductor-like screening model for real solvents (COSMO-RS) showed the compatibility of DPT with the DMSO solvent through hydrogen bonding. In the density functional theory (DFT) calculations, the formation energy of DPT and DPT-Cu were -1113.79645660 a.u. and -2435.71832681 a.u., respectively. Under optimal conditions, a detection limit of 1.47 ppm for the DPT chemosensor for Cu2+ recognition can compete with the atomic absorption spectroscopy (AAS) value of 1.50 ppm. The preliminary results show that DPT was able to provide less expensive, more portable and convenient chemosensor for Cu2+ recognition in aqueous medium, as compared to AAS.

Ion speciation: a key for the understanding of the solution properties of ionic liquid mixtures.

Recently, combinations of two (or more) ionic liquids, known as ionic liquid mixtures, have become popular and have a broad range of applications. However, the fundamental knowledge on the molecular interactions that exist in ionic liquid mixtures is far from being understood. In this work, the experimental measurement of the water activity coefficient and computational modelling using Conductor-like Screening Model for Real Solvent (COSMO-RS) were carried out to get an insight into the molecular interactions that are present in ionic liquid mixtures in aqueous solution. The results show that the combination of two ionic liquids of different basicity in aqueous solution allows fine tuning of the water activities, covering a wide range of values that could replace several pure fluids. This is an important feature resulting from the unexpected ion speciation of the ionic liquid mixtures in aqueous solution.

Feasibility of ionic liquid as extractant for bio-butanol extraction: Experiment and simulation

Separation of 1-butanol from the model fermentation broth (98 wt% water + 2 wt% ABE, acetone: 1-butanol: ethanol = 3: 6: 1) using liquid-liquid extraction (LLE) was investigated in this paper. This investigation involved multi-scale simulations from ab initio calculation to process simulation. Firstly, suitable extractant was screened from ionic liquids (ILs) combined of 30 anions and 40 cations using conductor-like screening model for real solvent (COSMO-RS) model. Meanwhile, the equilibrium experiment of the system ABE solution+selected IL was conducted to verify the screening result. From the screening, [HMIM][FEP] was found to be an optimal extractant and the experimental data confirmed this screening result with a deviation of 3.54%. The continuous hybrid process consisting of extraction and distillation section with the selected IL was also simulated and compared with a referenced process selecting mesitylene as extractant using Aspen Plus to investigate the performance of IL in real industry. The simulated results showed that a higher mass purities and yields of acetone (≥99.5 wt%), ethanol (≥99.5 wt%) and 1-butanol (≥99.9 wt%) could be obtained with much lower capital cost and energy consumption when the extractant was compared from [HMIM][FEP] to mesitylene. The extractant consumption and the energy consumption could lower 10% and 4.4% in total, respectively. The ab initio calculation enabled a deep insight on the mechanism of IL in extraction. Obviously, the results uncovered by the ab initio calculation showed that interaction between IL and 1-butanol was much stronger than mesitylene.

Estimating the saturation vapor pressures of isoprene oxidation products C&amp;lt;sub&amp;gt;5&amp;lt;/sub&amp;gt;H&amp;lt;sub&amp;gt;12&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;6&amp;lt;/sub&amp;gt; and C&amp;lt;sub&amp;gt;5&amp;lt;/sub&amp;gt;H&amp;lt;sub&amp;gt;10&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;6&amp;lt;/sub&amp;gt; using COSMO-RS

Abstract. We have used COSMO-RS (the conductor-like screening model for real solvents), as implemented in the COSMOtherm program, to compute the saturation vapor pressures at 298 K of two photo-oxidation products of isoprene: the dihydroxy dihydroperoxide C5H12O6, and the dihydroperoxy hydroxy aldehyde, C5H10O6. The predicted saturation vapor pressures were significantly higher (by up to a factor of 1000) than recent experimental results, very likely due to the overestimation of the effects of intramolecular hydrogen bonds, which tend to increase saturation vapor pressures by stabilizing molecules in the gas phase relative to the liquid. Modifying the hydrogen bond enthalpy parameter used by COSMOtherm can improve the agreement with experimental results – however the optimal parameter value is likely to be system-specific. Alternatively, vapor pressure predictions can be substantially improved (to within a factor of 5 of the experimental values for the two systems studied here) by selecting only conformers with a minimum number of intramolecular hydrogen bonds. The computed saturation vapor pressures were very sensitive to the details of the conformational sampling approach, with the default scheme implemented in the COSMOconf program proving insufficient for the task, for example by predicting significant differences between enantiomers, which should have identical physical properties. Even after exhaustive conformational sampling, COSMOtherm predicts significant differences in saturation vapor pressures between both structural isomers and diastereomers. For C5H12O6, predicted differences in psat between structural isomers are up to 2 orders of magnitude, and differences between stereoisomers are up to a factor of 20 – though these differences are very likely exaggerated by the overestimation of the effect of intramolecular H-bonds. For C5H10O6, the maximum predicted differences between the three studied structural isomers and their diastereomer pairs are around a factor of 8 and a factor of 2, respectively, when only conformers lacking intramolecular hydrogen bonds are included in the calculations. In future studies of saturation vapor pressures of polyfunctional atmospheric oxidation products using COSMOtherm, we recommend first performing thorough conformational sampling and subsequently selecting conformers with a minimal number of intramolecular H-bonds.

Bifunctional imidazole‐PTSA deep eutectic solvent for synthesizing long‐chain ester IBIBE in reactive extraction

The traditional production of long‐chain organic esters like isobutyl isobutyrate (BIBE) suffers from severe problems due to the homogenous catalyst in process and complex system thermodynamics. In this work, an innovative bifunctional deep eutectic solvent (DES) is introduced, playing as both reaction catalyst and extraction solvent, to intensify the esterification process. The DES was formed by imidazole (Im) and p‐toluenesulfonic acid (PTSA), which was for the first time found acid–base tunable, represented by weak basic DES [3Im:PTSA] and strong acidic DES [Im:2PTSA]. The formation mechanisms of [3Im:PTSA] and [Im:2PTSA] were illustrated by Fourier‐transform infrared spectroscopy (FTIR) and COnductor‐like Screening MOdel for Real Solvent (COSMO‐RS) combined with the Im‐PTSA phase diagram. The dual functions of the acidic [Im:2PTSA] in reactive extraction were evaluated by σ‐potential analysis and esterification experiments. The high conversion, easy product separation, and good solvent reusability confirm the excellent catalytic and solvent effect of [Im:2PTSA]. © 2018 American Institute of Chemical Engineers AIChE J, 65: 675–683, 2019

Separation of m-cresol from aromatic hydrocarbon and alkane using ionic liquids via hydrogen bond interaction

Abstract Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes; the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids (ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents (COSMO-RS) model and the liquid–liquid phase equilibrium (LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and n-heptane, 1-ethyl-3-methylimidazolium acetate (emimCH3COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emimCH3COO: model oils mass ratio of 0.5 and 298.15 K, emimCH3COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.

Numerical investigation of polyethylene glycol polymer (PEG) and dithymoquinone (DTQ) interaction using molecular modeling

In cancerous disease treatment, drug delivery process is the most decisive aspect. Selecting the appropriate carrier becomes crucial for higher drug effectiveness. Dithymoquinone (DTQ), as a potential anti-cancer drug, has a low solubility in aqueous media which probably can limit its potential use. To overcome this problem, polyethylene glycol (PEG) was chosen as a carrier to improve this property. Compatibility of this polymer at various degrees of polymerization with DTQ was investigated by means of molecular dynamics simulation (MD). Parameters including interaction energy of the polymer/DTQ systems, radius of gyration (Rg) of each polymer during simulation process and Flory-Huggins interaction were calculated. A Conductor-like Screening Model for Real Solvents (COSMO-RS) was used as a complementary study to show the polarity, affinity and reactivity of the PEG/DTQ systems. The different studies led to the same conclusion: PEG 60 is the more suitable polymer to encapsulate DTQ as a potential drug.

COSMO-RS predictions, hydrogen bond basicity values and experimental evaluation of amino acid-based ionic liquids for lignocellulosic biomass dissolution

In this study, the bamboo dissolution capability of six amino acid-based ionic liquids (AAILs) with two different cations, i.e. 1-ethyl-3-methylimidazolium (Emim) and Tetrabutylphosphonium (P4444) and three anions derived from amino acids were investigated by Conductor-like screening model for real solvents (COSMO-RS) prediction and hydrogen bond basicity (β) of Kamlet–Taft parameters. COSMO-RS was used for calculating sigma profile, activity coefficients (γi) and aqueous base dissociation constant of corresponding acids of the anions (pKa) of AAILs. The trends in sigma profile, γi and pKa for AAILs were compared with β values and the effect of structure moiety of ionic liquids was also discussed. The trend of COSMO-RS prediction for anions was noted similar to the β values of AAILs with the exception of serinate anion. Similarly, the trend predicted by COSMO-RS and β values was also found same while changing the cations of AAILs. To investigate, the correlation of the above-mentioned properties with experimental dissolution ability, tetrabutylphosphonium aminoethanic acid ([P4444]Gly) and 1-ethyl-3-methylimidazolium aminoethanic acid ([Emim]Gly) ionic liquids were synthesized and evaluated. The trend predicted by COSMO-RS and the β values were not correlating with efficiency of AAILs for bamboo dissolution. Both AAILs were able to dissolve the bamboo. However, material of [P4444]Gly treated sample was evaluated through XRD analysis where change in crystallinity of cellulose was identified after dissolution and regeneration of bamboo. Scanning Electron microscopy also showed homogenous structure for regenerated materials.

Prediction of Mefenamic Acid Solubility and Molecular Interaction Energies in Different Classes of Organic Solvents and Water

Determination of solubility data either through experimental- or model-based approaches becomes a necessity in the crystallization of pharmaceutical compounds. The current work predicts the mefenamic acid solubility and molecular interaction energy, namely electrostatic (H-MF), hydrogen bonding (H-HB), and van der Waals (H-vdW), in different solvents at temperatures from 298 to 323 K using the conductor-like screening model for real solvents (COSMO-RS). The solvents used were N,N-dimethylacetamide, N,N-dimethylformamide, acetone, ethyl acetate, ethanol, iso-propyl alcohol, n-hexane, n-heptane, cyclohexane, and water. The Gibbs free energy of fusion required in COSMO-RS computation was determined using differential scanning calorimetry and reference solubility method. The accuracy of methods employed in prediction of solubility were evaluated using mean squared quadratic error (MSE). The mefenamic acid solubility predicted using COSMO-RS with reference solubility method showed a small MSE value of less than 2%. The predicted solubility also follows the same trend as the experimental values and increases with temperature. The predicted H-HB energy and Gibbs free energy changes of mefenamic acid dissolution in the solvents studied highly influence the solubility data. Therefore, COSMO-RS with reference solubility method is a promising approach to predict the solubility and intermolecular interaction energy of mefenamic acid in different solvents.