Acid In Different Solvents Research Articles

The acidochromism of an N-methyl pyrrole-based enone dye toward trifluoroacetic acid in different solvents and solid state

Molecules with stimulus-response properties have always been a research hotspot. However, the acidochromism of enone dyes was rarely studied. In this work, the solvatochromism of an N-methyl pyrrole-based enone dye (C3PY) in nine organic solvents was firstly investigated by Kamlet–Taft equations. Then, with trifluoroacetic acid (TFA) as an example, the acidochromism of C3PY was investigated in nine solvents and solid state. Different acidochromism behaviors were observed and analyzed, which were discussed in terms of the solvent properties such as dielectric constant and basicity. A general mechanism was proposed and was supported by the 1H NMR acid titration experiments. Finally, the reversibility of acidochromism was evaluated and the application of C3PY as a TFA sensor was explored.

Dissolution Process and Thermodynamic Model Correlation of Homovanillic Acid in Different Solvents and Intermolecular Force Analysis

Dissolution Process and Thermodynamic Model Correlation of Homovanillic Acid in Different Solvents and Intermolecular Force Analysis

(R,S)-Mandelic acid in pure and binary solvents solubility measurement and its correlation with thermodynamic models

In this study, The solubility of (R,S)-mandelic acid in different solvents, including mono-solvent (H2O, methanol, ethanol, n-propanol, isopropanol) and binary solvents (methanol + H2O, ethanol + H2O, n-propanol + H2O, isopropanol + H2O, n-butanol + H2O), using analytical stirred-flask method and weight analysis method to determine the compositions of the saturated solutions at the atmospheric pressure. We found that the experimental solubility values increased with the rising of temperature accordingly. The experimental solubilities were correlated by the Ideal model, Apelblat model, λh (Buchowski) model, Wilson model, NRTL model. The results have shown that the Wilson model is the best model, which correlates the solubility of (R, S)-mandelic acid in the mono-solvent and binary solvents and fits well with experimental data. In addition, the thermodynamic properties of dissolution were calculated according to Van’t Hoff equation and experimental solubility, including Gibbs energy, entropy and enthalpy. The result confirms that the dissolution process in all solvents is always endothermic and entropy driven.

Solubility Determination and Thermodynamic Correlation of 3-Amino-2-methylbenzoic Acid in 12 Monosolvents from 288.15 to 328.15 K

A gravimetric method is adopted to measure the solid–liquid equilibrium of 3-amino-2-methylbenzoic acid in different solvents, including methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, isobutyl alcohol, 2-butanol, methyl acetate, ethyl acetate, propyl acetate, water, and acetonitrile. Moreover, the experiment is carried out at atmospheric pressure, and the temperature range is from 288.15 to 328.15 K. The solid–liquid equilibrium of 3-amino-2-methylbenzoic acid in all used solvents increases with increasing temperature. In alcohol solvents, except for isopropyl alcohol and 2-butanol, the solubility of 3-amino-2-methylbenzoic acid is positively related to the polarity of the solvent, which follows the “like dissolves like” rule. Because isopropyl alcohol and 2-butanol possess a high hydrogen bond acceptor propensity, this leads to a different solubility behavior. In nonalcohol solvents, the solid–liquid equilibrium of 3-amino-2-methylbenzoic acid also follows the “like dissolves like” rule. Among all 12 solvents, the solid–liquid equilibria of 3-amino-2-methylbenzoic acid in water and acetonitrile are lower than those in alcohols and esters. In addition, the solid–liquid equilibrium data of 3-amino-2-methylbenzoic acid were related by the modified Apelblat equation, van’t Hoff equation, and λh equation. Furthermore, all relevant results show consistency with the solid–liquid equilibrium data of 3-amino-2-methylbenzoic acid.

Understanding the solid-liquid phase equilibrium of 3,5-dimethoxybenzoic acid in thirteen pure solvents by thermodynamic analysis and molecular simulation

The solubility of 3,5-dimethoxybenzoic acid in 13 pure solvents range from 283.15 K to 323.15 K was investigated by the experiments and molecular simulations. Interestingly, its solubility in ethanol shows a particularity that is larger than that in n-butanol, which may be different from the expectation. This phenomenon was analyzed by molecular electrostatic potential surface (MEPs), Hirschfeld surface (HS), and radial distribution function (RDF) simulated by molecular dynamics (MD). The results indicate that the higher solubility of 3,5-dimethoxybenzoic acid in ethanol is due to the solute-solvent and solvent-solvent intermolecular hydrogen bonds. While in the investigation of the solubility in the esters, the relevant results of solvation free energy demonstrate that the solute-solvent interaction is dominant. The experimental data were further correlated with the van't Hoff model, λh model, the modified Apelblat equation and the NRTL model. All the overall ARD values are less than 4%. The modified Apelblat equation presents the best fitting effect. Furthermore, based on the NRTL model, the order of the obtained mixing Gibbs energy is consistent with the solubility order. Besides, its negative value indicates that the mixing process is spontaneous. The solubility of 3,5-dimethoxybenzoic acid in different solvents increases from 2-folds to 5-folds with the increasing temperature, which provides favorable conditions for the separation and purification of 3,5-dimethoxybenzoic acid in industrial production.

Thermodynamic models for determination of solid-liquid equilibrium of the 4-methoxybenzoic acid in different solvents with solubility parameters and interaction energy aided analyses

In this work, solubility data of 4-methoxybenzoic acid in eight pure organic solvents were measured by using a static gravimetric method at temperatures ranging from 273.15 K to 318.15 K under atmospheric pressure. The results showed that the solubility of 4-methoxybenzoic acid increased with the increasing of temperature in the investigated temperature range. The modified Apelblat equation, the λh equation, the NRTL model and the Wilson model were used to correlate the experimental solubility data of 4-methoxybenzoic acid in selected solvents and the calculated data showed that the Apelblat equation can give better correlation results. Meanwhile, Hansen solubility parameters analysis and density functional theory calculation of interaction energy were also used to investigate the mechanism of the solubility behavior of 4-methoxybenzoic acid in different solvents. Finally, the dissolution thermodynamic properties of 4-methoxybenzoic acid in different solvents, including Gibbs energy, entropy and enthalpy, were calculated based on the NRTL model and the experimental solubility data.

Measurement and PC-SAFT Modeling of the Solubility of Gallic Acid in Aqueous Mixtures of Deep Eutectic Solvents

Deep eutectic solvents have appeared as potential solvents for improving the extraction of polyphenols from vegetable or fruit matrixes. Since gallic acid is abundant in these sources, it is considered as a typical standard for quantifying their total polyphenol content after extraction with solvents. However, there are no extensive studies on the solubility behavior of gallic acid in different solvents or deep eutectic solvents. Thus, in this work, the solubility of gallic acid is measured in pure water; aqueous solutions of different hydrogen bond donors such as ethylene glycol, levulinic acid, and glycerol; and aqueous mixtures of deep eutectic solvents using choline chloride as the hydrogen bond acceptor and ethylene glycol, levulinic acid, and glycerol as the hydrogen bond donors. All of the measurements were performed at 293.15, 303.15, and 313.15 K and at 101.3 kPa and were validated by comparing the solubility of gallic acid in water from the literature. Results suggest that a 50 wt % aqueous solution of deep eutectic solvent based on ethylene glycol or glycerol improves the gallic acid solubility compared with a 50 wt % aqueous solution of its corresponding hydrogen bond donor. The deep eutectic solvent containing levulinic acid acts as the best aqueous mixture for gallic acid dissolution. Nondissolved gallic acid was measured after equilibrium using powder X-ray diffraction, showing that its structure does not change upon mixing with all of the liquid mixtures. All of the solid–liquid equilibrium results were accurately modeled with perturbed-chain statistical associating fluid theory (PC-SAFT).

Cannabidiol as the Substrate in Acid-Catalyzed Intramolecular Cyclization.

The chemical reactivity of cannabidiol is based on its ability to undergo intramolecular cyclization driven by the addition of a phenolic group to one of its two double bonds. The main products of this cyclization are Δ9-THC (trans-Δ-9-tetrahydrocannabinol) and Δ8-THC (trans-Δ-8-tetrahydrocannabinol). These two cannabinoids are isomers, and the first one is a frequently investigated psychoactive compound and pharmaceutical agent. The isomers Δ8-iso-THC (trans-Δ-8-iso-tetrahydrocannabinol) and Δ4(8)-iso-THC (trans-Δ-4,8-iso-tetrahydrocannabinol) have been identified as additional products of intramolecular cyclization. The use of Lewis and protic acids in different solvents has been studied to investigate the possible modulation of the reactivity of CBD (cannabidiol). The complete NMR spectroscopic characterizations of the four isomers are reported. High-performance liquid chromatography analysis and 1H NMR spectra of the reaction mixture were used to assess the percentage ratio of the compounds formed.

Kinetics study on reaction between dihydroartemisinic acid and singlet oxygen: An essential step to photochemical synthesis of artemisinin

Artemisinin is an excellent antimalarial drug widely used in clinical medicine. However, due to the limitation of natural source of artemisinin, the chemical synthesis of artemisinin has achieved substantial attention. Dihydroartemisinic acid is a key precursor for the synthesis of artemisinin. The reaction of dihydroartemisinic acid with singlet oxygen to form peroxide is a pivotal step in the photochemical preparation of artemisinin. Nevertheless, the reaction kinetics of dihydroartemisinic acid with singlet oxygen has not been investigated previously. Herein, we report the rate constants of the reaction between dihydroartemisinic acid and singlet oxygen. By directly detecting the luminescence decay kinetics of singlet oxygen at 1270 nm at room temperature, the reaction rate constants of singlet oxygen and dihydroartemisinic acid in different solvents are obtained to be 1.81×105 (mol/L)−1·s−1 in CCl4, 5.69×105 (mol/L)−1·s−1 in CH3CN, and 3.27×106 (mol/L)−1·s−1 in DMSO, respectively. It is found that the reaction rate constants of dihydroartemisinic acid with singlet oxygen increase as polarity of the solvent increases among the three solvents. These results provide fundamental knowledge to optimize experiment conditions of photochemical synthesis of artemisinin for improving the yields of artemisinin.

Solubility Determination and Thermodynamic Mixing Properties of 5-Methyl-2-pyrazinecarboxylic Acid in Different Solvents

The solubility of 5-methyl-2-pyrazinecarboxylic acid (MPCA) in 12 pure solvents within the temperature range from 273.15 to 313.15 K under 101.3 kPa was determined and correlated by some thermodyna...

Solubility, Model Correlation, and Solvent Effect of 2-Amino-3-methylbenzoic Acid in 12 Pure Solvents

In this experiment, the research of solution process for 2-amino-3-methylbenzoic acid in different solvents is essential for its purification. The solubility values in pure methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, acetonitrile, 2-butanone, ethyl acetate, 1,4-dioxane, toluene, and cyclohexane were established with the isothermal saturation method at temperatures T = 278.15 to 318.15 K under pressure of 101.2 kPa. The solubility of 2-amino-3-methylbenzoic acid in mole fraction increased with a rise of temperature. Moreover, at a certain temperature, the order of the solubility data from high to low is 1,4-dioxane > acetone > 2-butanone > ethyl acetate > acetonitrile > methanol > ethanol > 1-propanol > 1-butanol > 2-propanol > toluene > cyclohexane. The modified Apelblat equation, λh equation, Wilson model, and NRTL model were used to correlate the experimental data. The values of root-mean-square deviation (RMSD) and relative average deviation (RAD) were not exceeding 4.51 × 10–4 and 1...

Synthesis, spectroscopic characterization and DFT/TD-DFT computations of a novel charge transfer complex via hydrogen bonding between 3-amino-1,5-dimethylpyrazole with chloranilic acid in different solvents

A novel charge transfer complex including hydrogen bonding between the e-donor (H-acceptor) 3-amino-1,5-dimethylpyrazole (3-ADMP) with the e-acceptor (H-donor) chloranilic acid (CLA) has been synthesized and characterized experimentally and theoretically. The experimental work was carried out in different solvents including chloroform (CHL), ethanol (EtOH), methanol (MeOH) and acetonitrile (AN). The solution characterizations included the determining of the molecular composition of the formed CT complex where it recorded 1:1 (donor:acceptor) in all solvent. Also, estimating its formation constant by Benesie-Hildebrand equation where it recorded high values in all solvents, suggesting its high stability. Thermodynamic and some spectroscopic physical parameters were introduced and interpreted where they confirmed the presence of charge transfer besides hydrogen bonding in the formed complex. The solid complex was prepared and characterized by elemental analysis, infrared and NMR (1H and 13C) spectroscopies, the complex was formed in 1:1 ratio, with good evidences for existing both charge transfer and hydrogen bonding in its molecular structure. Density functional theory B3LYP-DFT at the basis set 6-31G (d,p) has been running out in gas phase and solution using chloroform and acetonitrile as solvents to compliment the measured results. The complex optimized structure included two hydrogen bonds between OH and CO of chloranilic acid with the adjacent ring nitrogen and amino group of pyrazole ring. The optimization energy, complexation energy, geometrical parameters, Mullikan atomic charges as well as molecular electrostatic potential maps (MEP) were calculated and interpreted; they consisted with the experimental results where the complex stability is attributed to the presence of H-bond beside e-transfer. The electronic spectra were computed using TD-DFT through adding polarizable continuum solvation method PCM, PCM-TD-DFT to compare with the experimental results. It has been found that, the measured and computed λmax are coming close to each other. The allowed singlet transitions are located and their HOMO and LUMO contributions are presented. The pictures of the frontier HOMO and LUMO molecular orbitals, participating in the first six singlet transitions were presented. A good consistency between experimental and DFT computations has been found.

Photophysical studies of the dye 1-Anilinonapthalene-8-sulfonic acid in different solvents and its quantum chemical investigation

Dyes are very much sensitive to solvents. Dye solvent interaction is specific and depends on solvent parameters and their compatibility. In the present study, the interaction of dye 1-Anilinonapthalene-8-sufonic acid (1,8-ANS) was investigated in different numbers of protic and aprotic solvents through photophysical method. In solvent the investigation of absorption and emission spectra of the dye were broad in nature with continuous amplification in intensity occur with increase in concentration of 2nd solvent by replacing water, reveals that there is feeble complex formation among molecules of dye and solvent. The dye and solvent molecular interactions are induced by synchronized effect of solvent parameter like dipole characteristic of solvent and intermolecular H bond formation ability of the media. Life time analysis of the dye through solvent dye interaction are the key factor to describe the spectroscopic feedback of 1,8-ANS. Theoretical analysis of DFT and TDSCF correlates the experimental spectral value.

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.

Experimental Assessment and Modeling of the Solubility of Malonic Acid in Different Solvents

Experimental Assessment and Modeling of the Solubility of Malonic Acid in Different Solvents

Solubility Measurement, Modeling, and Thermodynamic Functions for para-Methoxyphenylacetic Acid in Pure and Mixed Organic and Aqueous Systems

The solubility of para-methoxyphenylacetic acid in different solvents is of critical significance for the design and optimization of its purification process via crystallization. The present study illustrates new solid–liquid phase equilibrium data of para-methoxy phenyl acetic acid in water, acetonitrile, propan-2-ol, morpholine, toluene, anisole, and binary (propan-2-ol + water, propan-2-ol + toluene) mixed solvents using a static analytical method from 283.15 to 323.15 K at atmospheric pressure. The highest solubility of para-methoxyphenylacetic acid was observed in propan-2-ol and lowest in water, with the maximum solubility effect for propan-2-ol + toluene binary system obtained at 0.5001 solute-free mole fraction of propan-2-ol. The modified Apelblat equation, λh (Buchowski) equation, and nonrandom two-liquid (NRTL) activity coefficient model were used to correlate the experimental solubility data in pure solvents, whereas the binary solvent systems were modeled using the van’t Hoff–Jouyban–Acree, A...

Experimental Assessment and Modeling of the Solubility of Malonic Acid in Different Solvents

AbstractMalonic acid is widely applied in the pharmaceutical industry as a drug intermediate and for acidity control in drug production. Its solubility in five pure solvents and one binary solvent mixture was measured. The results reveal that, in the solvents studied, the solubility increases with increasing temperature. Different thermodynamic models were applied to correlate the solubility data in the pure and binary solvents and were found to match well with the experimental data. Computational investigations performed using molecular dynamics simulations showed that, in the pure alcohol solvents, both the solute‐solvent interaction and the solvent‐solvent interaction affect the solubility behavior, while in the case of the pure solvents acetone and acetonitrile, the solute‐solvent interaction is the key factor.

Solubility of 3-Caffeoylquinic Acid in Different Solvents at 291–340 K

Using a laser monitoring observation technique the solubilities of 3-caffeoylquinic acid in pure solvents, water, methanol, ethanol, 1-propanol, 1-butanol, and two mixed solvents, methanol + water, ethanol + water have been determined at temperature range from 291–340 K. The experimental data were correlated by the modified Apelblat equation, λh equation, and ideal model. The calculated solubilities were turned out very consistent with the experimental results, and the modified Apelblat equation shows the best agreement.

Thermodynamic models for determination of solid-liquid equilibrium of the 4-methylbenzoic acid in pure and binary organic solvents

Data on corresponding solid-liquid equilibrium of 4-methylbenzoic acid in different solvents are essential for a preliminary study of industrial applications. In this paper, the solid-liquid equilibrium of 4-methylbenzoic acid in methanol, ethanol, isopropanol, 1-butanol, acetone and acetonitrile pure solvents and (acetone+acetonitrile) mixture solvents were explored in the temperatures (from 278.15 to 323.15K) under atmosphere pressure. For the temperature range investigated, the solubility of 4-methylbenzoic acid in the solvents increased with increasing temperature. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, and the ideal model were adopted to describe and predict the change tendency of solubility. Computational results showed that the modified Apelblat model had more advantages than the other two models. The solubility data were fitted using a modified Apelblat equation, a variant of the combined nearly ideal binary solvent/Redich-Kister (CNIBS/R-K) model, Jouyban-Acree model and Ma model in (acetone+acetonitrile) binary solvent mixture. In addition, the calculated thermodynamic parameters indicated that in each studied solvents the dissolution of 4-methylbenzoic acid is endothermic and entropy-driven process.

The acid-base character of interactions between xenon and selected carboxylic and sulfonic acids

Interactions of Xe atoms with RCO2H and RSO3H (R=CH3 and CF3) acids in different solvents are examined by analysis of 129Xe chemical shifts extrapolated to zero solvent concentration. Obtained results are very sensitive to the Xe contacts with the methyl and trifluoromethyl groups as well as with the carboxylic and sulfonic groups of different acidity. The acid-base character of these acid-Xe interactions is considered.