Pure Solvents Research Articles

Solubility and Thermodynamic Modeling of 5-Nitrofurazone in Pure Solvents and Binary Solvent Mixtures

In this work, the solubility of 5-nitrofurazone (Form α) in 10 pure solvents (water, methanol, ethanol, acetonitrile, ethyl acetate, n-propanol, isopropanol, acetone, formamide, N,N-dimethylformamide) and two binary mixed solvents (N,N-dimethylformamide + water, N,N-dimethylformamide + acetonitrile) were measured by ultraviolet–visible spectrophotometry from 278.15 to 313.15 K. The experimental results showed that the solubility of 5-nitrofurazone (Form α) in all pure solvents and binary mixed solvents was positively correlated with temperature. Additionally, the modified Apelblat equation, the λh equation, and the nonrandom two-liquid (NRTL) model were used to correlate the experimental solubility results. The results showed that all of these models could correlate the experimental data well, and the modified Apelblat equation provided the best fitting results. Finally, the mixing and dissolution thermodynamic properties of 5-nitrofurazone (Form α) in 10 pure solvents and two binary solvents, including enthalpy, entropy, and Gibbs energy, were calculated by experimental results and the NRTL model.

Determination of L-Glutamine Solubility in 12 Pure Solvent Systems from 283.15 to 323.15 K

The mole fraction solubility of L-glutamine in 12 pure solvents (methanol, n-propanol, sec-butanol, 2-butanone, ethanol, acetonitrile, n-butanol, ethyl acetate, n-pentanol, water, n-hexane, and isobutanol) was determined by the static gravimetric method at a temperature range of 283.15–323.15 K under a pressure of 98.8 kPa. The equilibrium solid phase of L-glutamine in the solvent systems was characterized by powder X-ray diffraction analysis. The solubility in the 12 monosolvents was found to increase with absolute temperature. The maximum and minimum values were in water and ethyl acetate, respectively. The empirical solvent polarity parameters (ET(30)), cohesive energy density, and hydrogen bond donor/acceptor (HBD/HBA) tendencies were employed to analyze the solubility behavior and solvent effects. The solubility data were fitted using the modified Apelblat model and the Yaws model, at the same time, the model parameters and data deviation values were calculated. These two solubility models were evaluated using the Akaike Information Criteria and Akaike weights. The results showed that the modified Apelblat model had better correlation results. The solubility data could be used in the preparation and optimization of L-glutamine crystallization processes.

Demystifying Solvent Effects on Diels–Alder Reactions in Pure and Mixed Solvents: A Combined Electronic DFT and QM/MM Study

Although solvent effects on chemical reactions in pure solvents are well elucidated, both reaction mechanisms and solvent effects in mixed solvents remain poorly understood. Herein, the free energy profiles and the solute–solvent energy pair distribution of the Diels–Alder reaction in pure water, acetonitrile (ACN), carbon tetrachloride (CTC), and their mixtures ACN-water and ACN-CTC are calculated using the quantum and molecular mechanical (QM/MM) Monte Carlo method. The results show that the presence of solvent can significantly reduce the reaction free energy barrier, and the barrier in the mixed solvent is intermediate between the two pure solvents. Additionally, the free energy decomposition analysis demonstrated that the QM region dominates the reaction free energy. Electronic DFT calculations are employed to delineate the interactions between reactants and solvent molecules in pure and mixed solvents, with a particular focus on the role of electrostatic potential characteristics and an independent gradient model based on Hirshfeld partition. By rigorously analyzing these interactions, this study demystifies the mechanism underlying the phenomenon of preferential solvation and competition for reacting sites in mixed solvents, which alters the microenvironment of the solute.

Solubility Measurement of Cholesterol in Several Solvents from 283.2 to 323.2 K

The solubilities of cholesterol in methanol, anisole, acetic acid, ethyl acetate, heptane, methyl isobutyl ketone (MIBK), and mixed solvent (ethanol–MIBK) are determined in the temperature range of 283.2 to 318.2 K. The experimental solubilities of cholesterol in pure solvents and binary mixed solvents are found to increase with increasing temperature. In the binary mixed solvent (ethanol–MIBK), the cholesterol solubilities with increasing mass fraction of ethanol first increase and then decrease. The maximum cholesterol solubility can be obtained when the mass fraction of ethanol is approximately 10%. The solubilities of cholesterol in MIBK, ethyl acetate, and anisole are larger than those in methanol, heptane, and acetic acid. The experimental solubilities are correlated with the van′t Hoff, modified Apelblat, Yaws, van’t Hoff–Jouyban–Acree, and modified UNIQUAC models. The modified UNIQUAC model shows a better fitting result. The modified UNIQUAC model shows an average relative error (ARD) of less than 9%. The ARD values for the other models are all less than 12%.

Solubility behavior investigation of 1,4-cyclohexanedione in ten pure organic solvents by solubility measurement, correlation, DFT calculation and thermodynamic analysis

As an important raw material in industrial production, the solubility studies of 1,4-cyclohexanedione (14CHD) in organic solvents may be of assistance in improving crystallization efficiency and yield in industry. Therefore, this work deeply explored the dissolution behavior of 14CHD by using the isothermal saturation method, model fitting and density functional theory (DFT) calculation. Firstly, we selected ten pure organic solvents that are environmentally friendly to measure the solubility of 14CHD at the temperature range of 278.15 ∼ 313.15 K under standard atmospheric pressure. According to the measurement results, the solubility of 14CHD increases with temperature, and there are some differences among the solubility of 14CHD in various solvents. For instance, it has a highest solubility in acetonitrile (x1 = 0.5331) at 313.15 K while has the lowest solubility (x1 = 6.757 × 10-4) in cyclohexane at 283.15 K. Whereafter, the measured solubility data was correlated by Van't Hoff equation, modified Apelblat equation, λh model, Yaws model and Wilson model. Among them, Yaws model represents the most accurate fitting outcomes. At the same time, the study results of mixing thermodynamic properties on the basis of Wilson model suggest that the dissolution processes of 14CHD in ten organic solvents are entropy-driven and spontaneous. Afterwards, in order to explain the large difference in solubility of 14CHD in ten organic solvents, we found that the dissolution of 14CHD depends mostly on the polarity (π) and cohesive energy density (CED), viewed from the physicochemical factors of solvents. Furthermore, we further studied intermolecular interactions between 14CHD and ten solvents through molecular electrostatic potential surface (MEPS) analysis and DFT methods. Results display that alcoholic and non-alcoholic solvents molecules have different sites of action with 14CHD and the absolute values orders of interaction energies of alcoholic and non-alcoholic solvents are all consistent with corresponding solubility laws. The solvent–solute interaction plays an important role in the solubilities of 14CHD.

Solid-liquid phase equilibrium of adiphenine hydrochloride in twelve pure solvents

The solubility and apparent thermodynamic properties of Adiphenine hydrochloride (ADH) (Form I) in twelve mono-solvents including methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, n-amyl acetate, isopropyl acetate, isobutyl acetate, n-hexanol, n-heptanol, n-octanol, anisole and acetone were reported in this work. The solubility of ADH (Form I) was quantified by the laser monitoring method at atmospheric pressure and the selected temperature ranged from 278.15 K to 323.15 K. In the same solvent, the lower the temperature is, the less the solubility of ADH (Form I) is. A maximum mole fraction solubility of ADH (Form I) existed in n-hexanol (0.2241) at 323.15 K while the minimum mole fraction solubility (1.139 × 10−4) appeared in isopropyl acetate at 278.15 K. The experimental values of solubility were fitted by modified Apelblat model, NRTL model and UNIQUAC model, and it was found that the calculated values of the NRTL model and the modified Apelblat model were closer to the experimental values. The dipolarity/polarizability of the solvent and the acidity of the hydrogen bonds both play a positive role in increasing the solubility of ADH (Form I). The apparent thermodynamic properties of the dissolution process of ADH (Form I) were analyzed by the van't Hoff equation. It can be found that the dissolution process is an entropy-driven endothermic processes.

Hydrogen-Donor-Controlled Polybrominated Dibenzofuran (PBDF) Formation from Polybrominated Diphenyl Ether (PBDE) Photolysis in Solutions: Competition Mechanisms of Radical-Based Cyclization and Hydrogen Abstraction Reactions.

Polybrominated dibenzofurans (PBDFs) are characteristic dioxin-like products of polybrominated diphenyl ether (PBDE) photolysis. In this study, competition mechanisms of radical-based cyclization and hydrogen abstraction reactions are proposed in PBDF formation. Commonly, the ortho C-Br bond dissociation during photolysis generates aryl radicals, which undergo intramolecular cyclization to form PBDFs or hydrogen abstraction with hydrogen donors (such as organic solvents and water) to form lower brominated PBDEs. By using 2,4,4'-tribromodiphenyl ether (BDE-28) as the model reactant, the experimental PBDF formation ratios in various solutions are explained quantitatively by the calculated rate constants of cyclization and hydrogen abstraction reactions using the density functional theory (DFT) method. The solvent effect of pure and mixed solvents on PBDF formation is illustrated successfully. The structure-related hydrogen donation ability for hydrogen abstraction controls the bias of competition reactions and influences PBDF formation. Water resulted to be the most significant generation of PBDFs. Fulvic and humic acid display higher hydrogen donation ability than small-molecule organics due to the partitioning effect in aqueous solution. Quantitative structure-activity relationship (QSAR) models of the calculated rate constants for 512 cyclization and 319 hydrogen abstraction reactions using 189 PBDEs as the initial reactants in water are established, revealing the high risk of PBDF formation in aqueous solution.

Equilibrium Solubility, Modeling, and Extended Hildebrand Solubility Parameter Approach Analysis of 3-Amino-6-bromopyridazine in Four Cosolvent Blends and Ten Pure Solvents at T = 278.15 to 323.15 K

Equilibrium Solubility, Modeling, and Extended Hildebrand Solubility Parameter Approach Analysis of 3-Amino-6-bromopyridazine in Four Cosolvent Blends and Ten Pure Solvents at <i>T</i> = 278.15 to 323.15 K

How to obtain high monolayer content in liquid phase exfoliation of graphene: A molecular dynamic simulation

Monolayer is strong required in many fields of graphene-application, further insights into the efficient path of obtaining high monolayer content in liquid phase exfoliation of graphene are essential to explore it as a more potent alternative to chemical vapor deposition. Here, dynamic processes of shear exfoliation and narrow sense of liquid phase exfoliation in pure solvent and mixture solvent were investigated using molecular dynamics (MD) simulations to summarize an exfoliation scheme to obtain high monolayer content. By calculating the amount of shear force required for shear exfoliation, it has been found the requirement for the velocity gradient of solvent to monolayer graphene is 1011–1012 s−1, leading to a monolayer content of nearly 0 by shear exfoliation in all kinds of solvents. On the other hand, with solvent-insertion in narrow sense of liquid phase exfoliation, by investigating the influence of tensile force and shear force on gap formation, and the influence of solvent type on solvent-insertion and solvent-monolayer formation and stability, the conditions of high monolayer content has been summarized as follows: rapid insertion of solvent into the sheet interlayers to form solvent monolayer with moderate stability, which could be achieved only through the choice of the type of mixed solvent and the design of the external force applied. The types of mechanical force provided by commonly used mechanical operation were deduced, and in turn it is advised to use low speed agitation and ultrasound simultaneously at the initial phase and only agitation with large speed in the later stage of exfoliation process to obtain high monolayer content. This investigation provides theoretical clues and operational suggestions to obtain high monolayer content in liquid phase exfoliation of graphene and other two-dimensional lamellar materials.

Visualization of latent fingerprints using an AIE-active unsymmetrical azine: 2-Naphthol-pyrrole acrylate conjugate and its fluorescent sensing of Cu2+ and S2− ions, smartphone and logic gate applications

A novel, AIE-active unsymmetrical azine-based probe LH2 was designed and developed by simple condensation of ethyl-α-cyano-5-formyl-2-pyrroleacrylate and 1-(hydrazonomethyl)naphthalene-2-ol. The synthesized probe LH2 was characterized by NMR and mass spectrometric methods. Aggregation-induced emission (AIE) behavior of azine derivative, LH2 was examined in a DMSO-H2O mixture, where the compound displayed a weak emission in pure organic solvent DMSO, and the emission was found to be enhanced at 608 nm on increasing the water fraction owing to the occurrence of restriction of intramolecular rotation (RIR). The aggregation feature of LH2 was supported by DLS and FE-SEM studies. Further, the practical application of aggregates was established by imaging latent fingerprints (LFPs) over a TLC glass slide and other platofrms. In addition, the probe LH2 could selectively detect Cu2+ ions colorimetrically and fluorometrically in DMSO: H2O mixture over the other metal ions. More significantly, the naked eye-detectable color change of LH2 has been fruitfully integrated with an RGB color value app to make it suitable for easy on-site and real-time detection of Cu2+ ions. The LH2-Cu2+ ensemble displayed high selectivity towards S2− ion over other anions via displacement approach and such reversible On-Off-On emission characteristics were utilized for the construction of the IMPLICATION logic gate.

A comparative assessment for efficient oleuropein extraction from olive leaf (Olea europaea L. folium)

Since oleuropein has long been known in the health sector and is abundant directly in our country as the fourth largest olive producer, oleuropein, the predominant phenolic ingredient in olive leaves, was recovered in this study using Soxhlet extraction. The effects of different solvent types (acetonitrile, ethanol, methanol, and water), extraction period (4 cycles, 4 h, and 8 h), particle size (250-500 µm and 900-2000 µm), and pretreatment of olive leaves on the yield of oleuropein were examined to determine the maximum yield. A greater oleuropein yield was obtained when the particle size of olive leaves utilized for extraction was lowered. Furthermore, aqueous solvents revealed a higher yield of oleuropein than pure solvents and prolonging the extraction duration resulted in a significant increase in the amount of oleuropein extracted. On the other hand, pretreatment of olive leaves resulted in a reduction in oleuropein output. As a result, with 36% extraction efficiency in terms of olive leaf conversion, the highest oleuropein extraction yield was obtained as 13.35 mg g-1 dry leaf for 8 h of extraction time using olive leaves with a particle size of 250-500 µm and an 80% methanol solution as solvent.

Solubility and Thermodynamics Profile of Benzethonium Chloride in Pure and Binary Solvents at Different Temperatures.

Benzethonium chloride (BTC) has various applications in several industries. The solubility and solution thermodynamic properties of BTC were measured. The solubility of BTC in methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, water, dimethyl sulfoxide, acetic acid, and dimethyl formamide neat solvents and methanol + water and ethanol + water binary solvents at 298.15-318.15 K over an atmospheric pressure was measured. The solubility data of BTC is positively related to the temperature in all selected solvents. The solubility data was fitted by the Apelblat model, λh model, Yaws model, Van't Hoff equation, CNIBS/R-K model, and modified Jouyban-Acree equation. The RMSD and ARD were chosen to evaluate the fitting of each model. The dissolution thermodynamic parameters, enthalpy of the solution, entropy of the solution, and Gibbs energy of the solution were calculated. The solubility data and dissolution thermodynamic parameters of BTC will provide significant guidance for purification, crystallization, and separation in various areas.

Enthalpic Determination of the Interaction of Modified Activated Carbons with Benzene and Hexane as Pure Solvents and Binary Mixtures

Three activated carbons with different physicochemical characteristics are prepared and their N2 isotherms at 77 K and CO2 isotherms at 273 K are determined. The energetic interaction between three activated carbons with different physicochemical properties, and two hydrocarbons as pure liquids and as binary mixtures at different concentrations, was characterized by determining the enthalpy of immersion, in order to evaluate the effect of adsorbents and adsorbates, as well as that of the addition of another adsorbate to the system. For the pure solvents, the enthalpy of immersion (ΔHi) is higher for the aromatic compound (−94.98 to −128.80 J g−1) than for the aliphatic compound (−16.36 to −53.35 J g−1); for the mixtures, the values are between −36.39 and −98.37 J g−1, where the interaction increases with the solid that was subjected to thermal treatment and presented the lowest content of surface oxygenated groups, while the energetic parameter decreases with the solid that presents chemical modification with nitric acid, behavior that is evident in the pure solvents and in the mixtures. Activated carbons have a CO2 adsorption between 3.43 and 3.79 mmol g−1.

Rate of Advancement of Detection Limits in Mass Spectrometry: Is there a Moore's Law of Mass Spec?

Mass spectrometry is a well-established analytical technique for studying the masses of atoms, molecules, or fragments of molecules. One of the key metrics of mass spectrometers is the limit of detection e.g., the minimum amount of signal from an analyte that can be reliably distinguished from noise. Detection limits have improved greatly over the last 30-40 years to the point that nanogram per litre and even picogram per litre detections are commonly reported. There is however, a difference between detection limits obtained with a single, pure compound in a pure solvent and those obtained from real life samples/matrixes. Determining a practical detection limit for mass spectrometry is difficult because it depends on multiple factors, such as the compound under test, the matrix, data processing methods and spectrometer type. Here we show the improvements in reported limits of detection on mass spectrometers over time using industry and literature data. The limit of detection for glycine and dichlorodiphenyltrichloroethane were taken from multiple published articles spanning a period of 45 years. The limits of detection were plotted against the article's year of publication to assess whether the trend in improvement in sensitivity resembles Moore's Law of computing (essentially doubling every two years). The results show that advancements in detection limits in mass spectrometry are close to, but not quite at a rate equivalent to Moore's Law and the improvements in detection limits reported from industry seem to be greater than those reported in the academic literature.

Synthesis of 2D/2D structural Ti3C2 MXene/g-C3N4 via the Schottky junction with metal oxides: Photocatalytic CO2 reduction with a cationic scavenger

A series of Ti3C2/CN/Cu2O and Ti3C2/CN/ZnO ternary nanocomposites were successfully fabricated by the integration of 2D Ti3C2 MXene and 2D polymeric carbon nitride (CN) with ZnO and Cu2O. The HF etching on Ti3C2 MXene offered significant improvement for the photocatalyst fabrication, while the close 2D/2D junction of Ti3C2/CN created the Schottky junction to enable proficient electron transfer in the ternary nanocomposite. Next, the junction of 2D MXene and 2D CN with the metal oxides (Cu2O and ZnO) prevented the quick recombination of photoexcited electrons and holes and contributed multiple electron pathways for the CO2/CH3OH process. At the same time, the formation of analogue Z-scheme heterojunctions through the synergistic effect of 2D Ti3C2 MXene and 2D metal-free CN with ZnO contributed to the rapid separation and transfer of photogenerated charge carriers. As a result, the photocatalytic CO2 reduction activity of Ti3C2/CN/Cu2O and Ti3C2/CN/ZnO ternary nanocomposites was significantly enhanced. Meanwhile, adding a Na2SO3 sacrificial electron donor with pure water and NaHCO3 solvent system supply in CO2 photoreduction experiments contributed to the formation of CH3OH. In particular, the yield of CH3OH was up to 18.72% and 19.98%, 5times and 6-times fold than the pure Cu2O and ZnO, while 3-times fold than the TCCN in a water system. In a NaHCO3 solvent with the sacrificial electron donor, the CH3OH rates over Ti3C2/CN/ZnO and Ti3C2/CN/Cu2O were 22.41% and 20.12%. Taking into account the chemical and structural tunability of ternary nanocomposites, the excellent photocatalytic ability of Ti3C2/CN/ZnO and Ti3C2/CN/Cu2O could be used in the future production of hydrocarbon fuels, as well as increasing the possibility of using 2D MXene in photocatalyst fabrication.

On Nanobubble Dynamics under an Oscillating Pressure Field during Salting-out Effects and Its DLVO Potential

We have investigated the origin, stability, and nanobubble dynamics under an oscillating pressure field followed by the salting-out effects. The higher solubility ratio (salting-out parameter) of the dissolved gases and pure solvent nucleates nanobubbles during the salting-out effect, and the oscillating pressure field enhances the nanobubble density further as solubility varies linearly with gas pressure by Henry's law. A novel method for refractive index estimation is developed to differentiate nanobubbles and nanoparticles based on the scattering intensity of light. The electromagnetic wave equations have been numerically solved and compared with the Mie scattering theory. The scattering cross-section of the nanobubbles was estimated to be smaller than the nanoparticles. The DLVO potentials of the nanobubbles predict the stable colloidal system. The zeta potential of nanobubbles varied by generating nanobubbles in different salt solutions, and it is characterized by particle tracking, dynamic light scattering, and cryo-TEM. The size of nanobubbles in salt solutions was reported to be higher than that in pure water. The novel mechanical stability model is proposed by considering both ionic cloud and electrostatic pressure at the charged interface. The ionic cloud pressure is derived by electric flux balance, and it is found to be twice the electrostatic pressure. The mechanical stability model for a single nanobubble predicts the existence of stable nanobubbles in the stability map.

Optimization of a silicon-based microencapsulation technology of phase change material without organic solvents

Phase change microcapsules (MPCM) have significant advantages, such as fast thermal response and low leakage rate, which can be widely used in construction, textile, and electric power fields. However, the existing microcapsule preparation process has high costs and complicated steps, which limits its popularization and application. This paper reports a de-organic reform of the in-situ polymerization method for the fabrication of MPCM. The aqueous phase (solvent) consisted of pure deionized water and surfactant instead of conventional partial or pure organic solvents such as ethanol and acetamide. Taking the type and content of surfactant, homogenization speed, solvent ratio and core-shell ratio as the research variables, the optimal fabrication scheme of silicon-based MPCM in an alkaline environment was confirmed. The results showed that the Pa@SiO2 microcapsules prepared by pure inorganic solvents had great shape stability to prevent phase change material leakage and great temperature regulation performance when appropriate amount of hexadecyl trimethyl ammonium bromide was the surfactant and 3-Aminopropyltriethoxysilane was the silane coupling agent. More importantly, it has high heat storage capacity of 191.5 J/g due to its excellent encapsulation ratio of 76.4 %. Therefore, the fabrication method without organic solvent can simplify the fabrication process and greatly reduce the fabrication cost while ensuring excellent thermal properties of microcapsules, especially the outstanding heat storage capacity, which shows great application prospects in terms of microcapsule large-scale production.

Solubility Modeling and Preferential Solvation of Benzamide in Some Pure and Binary Solvent Mixtures at Different Temperatures

Solubility Modeling and Preferential Solvation of Benzamide in Some Pure and Binary Solvent Mixtures at Different Temperatures

Intramolecular and Intermolecular Interaction Switching in the Aggregates of Perylene Diimide Trimer: Effect of Hydrophobicity

The research on perylene diimide (PDI) aggregates effectively promotes their applications in organic photovoltaic solar cells and fluorescent sensors. In this paper, a PDI fabricated with three peripheral PDI units (N, N'-bis(6-undecyl) perylene-3,4,9,10-bis(dicarboximide)) is investigated. The trimer shows different absorption and fluorescence properties due to hydrophobicity when dissolved in the mixed solvent of tetrahydrofuran (THF) and water. Through comprehensive analysis of the fluorescence lifetime and transient absorption spectroscopic results, we concluded that the trimer underwent different excited state kinetic pathways with different concentrations of water in THF. When dissolved in pure THF solvent, both the intramolecular charge-transfer and excimer states are formed. When the water concentration increases from 0 to 50% (v/v), the formation time of the excimer state and its structural relaxation time are prolonged, illustrating the arising of the intermolecular excimer state. It is interesting to determine that the probability of the intramolecular charge-transfer pathway will first decrease and then increase as the speed of intermolecular excimer formation slows down. The two inflection points appear when the water concentration is above 10% and 40%. The results not only highlight the importance of hydrophobicity on the aggregate properties of PDI multimers but also guide the further design of PDI-based organic photovoltaic solar cells.

Measurement and correlation of solubility of 9-fluorenone in 11 pure organic solvents from T = 283.15 to 323.15 K

In this work, the solubility data of 9-fluorenone in 11 pure solvents (methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, acetonitrile, ethyl formate, ethyl acetate, dimethyl sulfoxide, n-hexane) were measured by the gravimetric method from 278.15 K to 318.15 K under atmospheric pressure. The results showed that the solubility of 9-fluorenone in all tested solvents increased with the raised temperature. The solubility data were correlated by the modified Apelblat equation, λh model and NRTL (non-radom two fluid) model. The average relative deviation (ARD) correlated by three thermodynamic models in different solvents was all below 5%, which indicated that the three thermodynamic models fit the solubility data well. Furthermore, the mixing thermodynamic properties of 9-fluorenone in pure solvent systems were calculated via NRTL model. The results indicated the dissolution process of 9-fluorenone is spontaneous and entropically favorable. The solubility and the mixing thermodynamic properties provided in this paper would play an important role in industrial manufacture and follow-up operation of 9-fluorenone.