Aqueous Mixtures Of Methanol Research Articles

Review of Solvation Studies of Copper (1) Complexes in Different Solvents and at Different Temperatures

The study of the solvation behavior of copper (1) complexes in the mixed solvents has generated a great interest in the field of chemistry. Copper complexes have attracted wide attention due to their important role in analytical chemistry, organic synthesis, metallurgy and medicines etc. Nevertheless, during recent years there has been an increasing interest in the behavior of copper (1) complexes in aqueous and non-aqueous solvents with a view to investigate ion-ion and ion solvent or solute solute interactions under varied conditions. The solvation behavior of some copper(I) perchlorate complexes in binary mixtures of dimethylsulfoxide with dimethylacetamide and dimethylformamide at 298k, and Some Copper(I) Nitrate Complexes in Dimethylsulfoxide and Nitromethane at 298 K and copper sulfate have been measured in binary mixtures of aqueous–methanol mixtures at different temperatures is studied by a combined approach using Molar conductance, ultrasonic velocity and density data, or limiting molar conductance (Λ0), the association constants (KA) respectively . This study is a condensed version of earlier work in the same fields. Keywords: solvation, Molar conductance, Copper sulfate, copper(I) perchlorate

The non-ideality in binary aqueous systems contributed to the different abilities of solvent entities incorporated in the solvation shell of methylene blue

The solvatochromic properties of methylene blue (MB) were investigated in neat water, methanol, ethanol, propanol, dioxane and their corresponding aqueous mixtures. The correlation of the empirical solvent polarity scale (ET) values of MB with solvent composition was analysed using the solvent exchange model of Bosch and Roses to explain the preferential solvation of the probe thiazine dye in the binary mixed solvents. Non-linear solvatochromism of MB was observed in aqueous mixtures of methanol, ethanol, propanol and dioxane. The influence of the composition of the solvating shell in preferential solvation of the solute dye was investigated in terms of both solvent?solvent and solute?solvent interactions, and the local mole fraction of each solvent composition in the cybotactic region of the probe was also calculated. Effective mole fraction variation can provide important physicochemical insights into the microscopic and molecular interactions between MB species and solvent components. The results showed that the MB solvation shell was thoroughly saturated with the solvent complex S12 for dioxane more than ethanol and propanol mixtures, and opposite trends for methanol mixtures, whereas the solvent complex S12 could not incorporate into the MB solvation shell. Data from the binary systems were analysed with KAT parameters using a dual model of basicity and polarity. The results showed that the polarity was better suited for spectral shift in aqueous methanol and ethanol solutions, while the basicity was better for aqueous propanol and dioxane solutions.

Preferential solvation of 5,7-dihydroxyflavone (chrysin) in aqueous co-solvent mixtures of methanol and ethanol

ABSTRACT The inverse Kirkwood-Buff integrals were used to calculate the preferential solvation parameters of the natural polyphenolic compound chrysin in binary mixtures of ethanol (1) + water (2) and methanol (1) + water (2) as a function of their thermodynamic properties. At temperatures between 298.15 K and 318.15 K, chrysin is extremely sensitive to specific solvation effects; therefore, the negative values of were found in the water-rich range of 0 < x1 < 0.30 for methanol (1) + water (2) and 0 < x1 < 0.25 for ethanol (1) + water (2) which suggested that water (2) preferentially dissolves chrysin (3). In co-solvent-rich regions, the values of were positive, and the co-solvents preferentially dissolve chrysin (3). The solvation of drugs in water-rich mixtures is likely to be facilitated by hydrophobic hydration around aromatic rings or groups.

Excess Molar Volumes, Apparent Molar Volumes, Partial Molar Volumes of Methionine, An Amino Acid, in Water + Ethanol And Water + Methanol Solutions at 298.15 K

Methionine is an amino acid that is extremely important for human health. To better understand the biochemical events occurring in the human body, the excess molar properties of methionine and aqueous ethanol and aqueous methanol mixtures were determined at 298.15 K. Interactions between components in solutions are explained. Negative deviations from the ideal state have been observed in methionine solutions due to hydrogen bonds, dipole interactions, charge-transfer interactions.

Application of Polarisable Continuum Modelling to assess Minoxidil solubility in mixed solvents

ABSTRACT Experimental solubility of minoxidil was obtained in binary aqueous mixtures of ethanol, methanol and acetonitrile at 298.2 K. The effects of pH and micellisation were investigated on the solubility of the drug. Experimental solubility data was correlated by three co-solvency models, i.e. Yalkowsky, CNIBS/R-K, and the modified Wilson model. Density functional theory and hybrid functional B3LYP method was used with Polarisable Continuum Model (PCM) to correlate the experimental solubility data in various mass fractions of the binary solvent mixtures. We report the results of solute–solvent interaction energy as free energy of solvation (∆G sol ) of minoxidil in various mass fractions of ethanol + water mixtures. Total electrostatic energy, dipole moment, total Gibbs free energy and dielectric constant (ε) of minoxidil were also investigated.

Thermodynamic Characteristics of Phenacetin in Solid State and Saturated Solutions in Several Neat and Binary Solvents.

The thermodynamic properties of phenacetin in solid state and in saturated conditions in neat and binary solvents were characterized based on differential scanning calorimetry and spectroscopic solubility measurements. The temperature-related heat capacity values measured for both the solid and melt states were provided and used for precise determination of the values for ideal solubility, fusion thermodynamic functions, and activity coefficients in the studied solutions. Factors affecting the accuracy of these values were discussed in terms of various models of specific heat capacity difference for phenacetin in crystal and super-cooled liquid states. It was concluded that different properties have varying sensitivity in relation to the accuracy of heat capacity values. The values of temperature-related excess solubility in aqueous binary mixtures were interpreted using the Jouyban–Acree solubility equation for aqueous binary mixtures of methanol, DMSO, DMF, 1,4-dioxane, and acetonitrile. All binary solvent systems studied exhibited strong positive non-ideal deviations from an algebraic rule of mixing. Additionally, an interesting co-solvency phenomenon was observed with phenacetin solubility in aqueous mixtures with acetonitrile or 1,4-dioxane. The remaining three solvents acted as strong co-solvents.

Imidacloprid (I) in several aqueous co-solvent mixtures: Solubility, solvent effect, solvation thermodynamics and enthalpy–entropy compensation

This contribution dealt with the saturated solubility, solvation behavior, and dissolution and transfer belongings of imidacloprid in some aqueous co-solvent mixtures of n-propanol, acetone, ethanol and methanol by means of experiment and mathematical correlations. Solubility experiments were conducted via a commonly used technique, namely shake-flask method, under 101.2 kPa from 283.15 to 323.15 K. The maxima of the obtained imidacloprid solubility was recorded in neat n-propanol/acetone/ethanol/methanol at temperature T = 323.15 K, which corresponded to 227.7 × 10−5, 2851 × 10−5, 237.9 × 10−5 and 409.9 × 10−5 (mole fraction), respectively; and the minimum, in single water (0.6792 × 10−5 at 283.15 K). The Hansen solubility parameters were used here to illustrate the imidacloprid solubility behavior. Solubility modeling through Jouyban–Acree–van’t Hoff, mixture response surface (MRS), Jouyban–Acree and modified Wilson models achieved the relative average deviations of no higher than 3.01%. As well, the extended Hildebrand solubility approach analyzed the saturated solubility of imidacloprid at 298.15 K attaining the maximum of relative average deviation (RAD) of 1.16%. The key contributions of solution descriptors to the imidacloprid solubility were observed as dipolarity-polarizability and solubility parameter studied through molecular interactions of solvent-solvent and solute-solvent species to the imidacloprid solubility in terms of the linear solvation energy relationships. A quantitatively investigation upon local mole fractions was executed by utilizing the powerful tool of inverse Kirkwood–Buff integrals through considering several properties of solutions. The local mole fractions of n-propanol/acetone/ethanol/methanol were higher than that of the bulk ones in n-propanol/acetone/ethanol/methanol-rich and middle proportions, representing preferential solvation of the imidacloprid by co-solvents (n-propanol/acetone/ethanol/methanol). It is speculated within these regions imidacloprid acts as a Lewis acid with the molecules of co-solvents. Thermodynamic calculation of dissolution properties and enthalpy–entropy compensation study revealed an entropy-driven mechanism and endothermic process of imidacloprid dissolved in blended solvents. Transfer property analysis designated more advantageous solubilization ability over the intermediate and rich-co-solvent contents.

Directed evolution of unspecific peroxygenase in organic solvents.

Fungal unspecific peroxygenases (UPOs) are efficient biocatalysts that insert oxygen atoms into nonactivated C-H bonds with high selectivity. Many oxyfunctionalization reactions catalyzed by UPOs are favored in organic solvents, a milieu in which their enzymatic activity is drastically reduced. Using as departure point the UPO secretion mutant from Agrocybe aegerita (PaDa-I variant), in the current study we have improved its activity in organic solvents by directed evolution. Mutant libraries constructed by random mutagenesis and in vivo DNAshuffling were screened in the presence of increasing concentrations of organic solvents that differed both in regard to their chemical nature and polarity. In addition, a palette of neutral mutations generated by genetic drift that improved activity in organic solvents was evaluated by site directed recombination in vivo. The final UPO variant of this evolutionary campaign carried nine mutations that enhanced its activity in the presence of 30% acetonitrile (vol/vol) up to 23-fold over PaDa-I parental type, and it was also active and stable in aqueous acetone, methanol and dimethyl sulfoxide mixtures. These mutations, which are located at the surface of the protein and in the heme channel, seemingly helped to protect UPO from harmful effects of cosolvents by modifying interactions with surrounding residues and influencing critical loops.

Evodiamine in several binary aqueous co-solvents: Solubility measurement and modeling, Hansen solubility parameter, preferential solvation and apparent dissolution and transfer properties

Equilibrium solubilities of evodiamine were determined in four aqueous mixtures of methanol, isopropanol, acetone and ethanol over their full mass fraction range via the shake-flask approach covering from 283.15 to 323.15 K. The solubility profiles showed maxima in the neat cosolvents. The temperature and the mixture composition dependence of evodiamine solubility in mole fraction scale was well described by using five well-known models involving NRTL, Jouyban-Acree, van't Hoff-Jouyban-Acree, UNIQUAC and Wilson. The means of the relative deviations were recorded as 5.40%, 0.98% and 0.48% for the Wilson, UNIQUAC and NRTL models, respectively. The Jouyban-Acree and van't Hoff-Jouyban-Acree models resulted in the calculated relative average and root-mean-square deviations lower than 6.83% and 9.19 × 10−6, respectively. Hansen solubility parameter was utilized to disclose the solubility behavior of evodiamine. We also employed the linear solvation energy relationships to detect which intermolecular interactions were mainly responsible for the observed solvent effect upon solubility behavior. This analysis revealed the highlighted role of cavity term and dipolarity-polarizability of solvent in solubility variation of evodiamine. Solubility data was further examined by using the inverse Kirkwood-Buff integrals method in order to analysis the preferential solvation of evodiamine in the mixtures. Results showed the selective solvation of evodiamine by organic solvent in intermediate and organic solvent-rich compositions, and by water in water-rich compositions. The thermodynamic quantities including the apparent molar dissolution enthalpy, molar dissolution entropy and molar Gibbs energy, and the relative contribution of dissolution enthalpy and dissolution entropy to the dissolution Gibbs energy change for dissolution of evodiamine were calculated in each binary mixture. Moreover, the transfer properties were derived and discussed.

Association Constant And Free Energy Change Properties Of Sodium Salt Of 1-Butane Sulphonic Acid In Aqueous Meoh And Aqueous Dmso Composition

Various elements similar to density, viscosity, medium dielectric constant, ion-solvent relationships, and measurements of solvent-solvent, form properties of ion-conductance and ion solvation related to different solvent electrolytes. In solving it, ion-solvent relations pacify the ion. In the analysis of ion solvent associations and ion solvation activities, conductance data and association constant figures of distant electrolytes are used. Conductance and ion solving properties of 1-butane sulphonic acid sodium salt measured in aqueous methanol and aqueous DMSO of varying composition in the 298 K to 318 K-temperature range. Limiting molar conductance, ion pair interaction constants, KA using Shedlovsky limiting law to work out. With the percentage of water in the solvent mixture, ∧0 increases. In 80% aqueous-methanol mixture, KAvalue and free energy changes are maximum, indicating that ion-solvent interactions are maximum in this composition of solvent blend and ion conductance properties as a purpose of clear ion-solvent links, including structural influence.

Solubilisation of dexamethasone: experimental data, co-solvency and Polarised Continuum Modelling

ABSTRACT Experimental solubility of dexamethasone was obtained in binary aqueous mixtures of ethanol, methanol and acetonitrile at 298.2 K. The effects of micellization and pH were also investigated on the solubility of the drug. Experimental solubility data in the binary solvent mixtures were correlated by three co-solvency models, i.e. Yalkowsky, CNIBS/R-K, and the modified Wilson model. A new principle has also been investigated with the purpose of modelling drug solubility in the binary solvent mixtures using Polarised Continuum Model (PCM) by using the hybrid functional B3LYP method and 6–311++G** basis set. By matching experimental data with PCM modelling, we investigated the outcome of drug solubility in various mass fractions of binary solvent mixtures. Here we report the solute-solvent interaction energy as free energy of solvation (∆Gsol), total electrostatic energy, dipole moment, total Gibbs-free energy and dielectric constant (ε) of dexamethasone in various mass fractions of ethanol + water mixtures.

Bezafibrate in several aqueous mixtures of low alcohols: Solubility, solvent effect and preferential solvation

By using the saturation shake-flask method, the saturated solubility of bezafibrate in neat water, methanol, ethanol, n-propanol and isopropanol and aqueous co-solvent mixtures of methanol (1) + water (2), ethanol (1) + water (2), isopropanol (1) + water (2) and n-propanol (1) + water (2) was experimentally acquired at temperatures from 283.15 Kto 323.15 K and local atmospheric pressure. The maximum solubility magnitudes in mole fraction were recorded in the neat solvents of methanol/ethanol/n-propanol/isopropanol for corresponding solutions. The mole fraction solubility was described mathematically by using the van’t Hoff-Jouyban-Acree and Jouyban-Acree models. The largest value of relative average deviations was 6.23%; and, root-mean-square deviations, 8.92 × 10−5. The local mole fractions of water and co-solvent (methanol, ethanol, n-propanol or isopropanol) around the drug bezafibrate were quantitatively investigated by the use of Inverse Kirkwood–Buff integrals method. Results indicated that the bezafibrate was preferentially solvated by methanol (ethanol, n-propanol or isopropanol) in alcohol-rich and intermediate compositions in the alcohol mixtures; while in water-rich compositions, bezafibrate was preferentially solvated by water. The main factors relating to solvent effect were inspected through Kamlet and Taft linear solvation energy relationships, demonstrating that the cavity formation energy and dipolarity-polarizability in methanol solutions, cavity formation energy and basicity in ethanol solutions, and cavity formation energy in n-propanol (isopropanol) solutions played the principal role upon the bezafibrate solubility variation.

Equilibrium solubility determination and thermodynamic aspects of aprepitant (form I) in four binary aqueous mixtures of methanol, ethanol, acetone and 1,4-dioxane

This contribution reported the equilibrium solubility of aprepitant (form I) in four binary aqueous mixtures of methanol, ethanol, acetone and 1,4-dioxane acquired through a shake-flask method from 283.15 K to 323.15 K under local atmospheric pressure of 101.2 kPa. At the same mass fraction compositions of methanol/ethanol/acetone/1,4-dioxane and temperature, the mole fraction solubility of aprepitant was greater in (1,4-dioxane + water) mixture than in ethanol/acetone/methanol (1) + water (2) mixtures. The relative importance of solute-solvent and solvent-solvent interactions upon the solubility variation was studied by using the linear solvation energy relationships of solvent effect. The Hildebrand solubility parameter and dipolarity-polarizability of the solvents had the main contributions to the solubility variation in methanol/ethanol/1,4-dioxane + water mixtures; while merely dipolarity-polarizability, in (acetone + water) mixture. The preferential solvation was studied by using the method of inverse Kirkwood-Buff integrals in terms of thermodynamic solution properties. The preferential solvation parameters for methanol, ethanol, acetone and 1,4-dioxane presented positive values in methanol/ethanol/acetone/1,4-dioxane-rich and intermediate compositions in the four mixtures, indicating that aprepitant (I) was solvated preferentially by the methanol/ethanol/acetone/1,4-dioxane. It is conjecturable that in these regions aprepitant (I) acts as a Lewis acid with methanol/ethanol/acetone/1,4-dioxane molecules. Moreover, the drug’s solubility was mathematically represented via the Jouyban-Acree model obtaining the average relative deviations less than 6.21%. Finally, the standard dissolution enthalpies (ΔHsolo) for aprepitant (I) dissolved in solvent mixtures were obtained from the van’t Hoff analysis.

Further study on enantiomer resolving ability of amylose tris(3-chloro-5-methylphenylcarbamate) covalently immobilized onto silica in nano-liquid chromatography and capillary electrochromatography

In the present study separation of enantiomers of some chiral neutral, basic and weakly acidic analytes was investigated on the chiral stationary phase (CSP) made by covalent immobilization of amylose tris(3-chloro-5-methylphenylcarbamate) onto aminopropylsilanized (APS) silica in nano-liquid chromatography (nano-LC) in aqueous methanol or acetonitrile mixtures. It has been shown that similar to high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) this chiral selector is useful for separation of enantiomers of neutral, basic and acidic analytes also in nano-LC. In comparison to our previous research, in which the chiral selector (CS) was bonded on native silica, in this study, the CS was immobilized on APS silica in order to improve chromatographic performance towards basic analytes. In fact, some improvement was observed and surprisingly not only for basic but also for neutral and acidic analytes. Again, quite unexpectedly almost no electroosmotic flow (EOF) was observed in capillaries packed with ca. 20% (w/w) amylose tris(3-chloro-5-methylphenylcarbamate) immobilized onto APS silica although the same APS silica before attachment of chiral selector exhibited significant EOF. In order to generate EOF in the capillaries with the CSP and enable capillary electrochromatographic (CEC) experiment on it, the short segment of the capillary column was packed with APS silica without chiral selector. The EOF in such capillary enabled CEC experiment and some preliminary results are reported here.

6-Phenyl-3(2H)-pyridazinone dissolved in some aqueous co-solvent mixtures of alcohols: Equilibrium solubility, solvent effect and preferential solvation

The saturated solubility of 6-phenyl-3(2H)-pyridazinone in aqueous co-solvent mixtures of methanol, ethanol, isopropanol and ethylene glycol (EG) was determined through experiment by employing the saturation shake-flask method at temperatures from 278.15 to 318.15 K and local atmospheric pressure. For all the co-solvent mixtures, the maximum value of solubility was observed in neat methanol (ethanol, isopropanol or EG). The 6-phenyl-3(2H)-pyridazinone solubility in mole fraction scale was well correlated by using the Jouyban-Acree model and van’t Hoff-Jouyban-Acree model, obtaining the values of relative average deviations smaller than 3.98%; and root-mean-square deviation, lower than 7.81 × 10−5. The local mole fractions of methanol (ethanol, isopropanol or EG) and water nearby the 6-phenyl-3(2H)-pyridazinone were quantitatively calculated by means of the Inverse Kirkwood-Buff integrals method. 6-Phenyl-3(2H)-pyridazinone was preferentially solvated by the solvent of water in water-rich compositions; while within the regions of co-solvent-rich and intermediate compositions, 6-phenyl-3(2H)-pyridazinone was preferentially solvated by the solvent of methanol (ethanol, isopropanol or EG). The mole fraction solubility was fitted by using the Kamlet and Taft linear solvation energy relationships to inspect the key factors describing solvent effect. The variation in cavity formation energy and hydrogen-bond acidity played the chief role upon the 6-phenyl-3(2H)-pyridazinone solubility in aqueous solutions of methanol and ethanol; and the hydrogen bond acidity and dipolarity/polarizability term, in the aqueous of mixtures isopropanol and EG .

Hesperetin Solubility in Aqueous Co-solvent Mixtures of Methanol and Ethanol: Solute Descriptors, Solvent Effect and Preferential Solvation Analysis

Solubility data for hesperetin in pure solvents and alcohol-rich regions of aqueous mixtures of methanol and ethanol were used to derive the solute descriptors for solubility prediction of hesperetin by using the Abraham solvation parameter model. Solubility data in aqueous mixtures of methanol and ethanol were analyzed by the linear solvation energy relationships approach to provide detailed insight into the solvent effect. In this regard, energy terms for solute–solvent and solvent–solvent interactions were defined in terms of dipolarity–polarizability, hydrogen bond basicity, hydrogen bond acidity and Hildebrand solvent parameter. Results indicate that the main contribution was from solvent–solvent interactions represented by the cavity term. Preferential solvation analysis was performed with the help of inverse Kirkwood–Buff integrals approach. Local composition and preferential solvation parameter were calculated as a function of mole fraction of methanol and ethanol. Results show that hesperetin is preferentially surrounded by water in water-rich regions, whereas methanol or ethanol are preferred in other compositions. This observation was discussed in terms of the solute hydrophobic hydration and specific hydrogen bonding interactions.

Multiple Free Energy Calculations from Single State Point Continuous Fractional Component Monte Carlo Simulation Using Umbrella Sampling.

We introduce an alternative method to perform free energy calculations for mixtures at multiple temperatures and pressures from a single simulation, by combining umbrella sampling and the continuous fractional component Monte Carlo method. One can perform a simulation of a mixture at a certain pressure and temperature and accurately compute the chemical potential at other pressures and temperatures close to the simulation conditions. This method has the following advantages: (1) Accurate estimates of the chemical potential as a function of pressure and temperature are obtained from a single state simulation without additional postprocessing. This can potentially reduce the number of simulations of a system for free energy calculations for a specific temperature and/or pressure range. (2) Partial molar volumes and enthalpies are obtained directly from the estimated chemical potentials. We tested our method for a Lennard-Jones system, aqueous mixtures of methanol at T = 298 K and P = 1 bar, and a mixture of ammonia, nitrogen, and hydrogen at T = 573 K and P = 800 bar. For pure methanol (N = 410 molecules), we observed that the estimated chemical potentials from umbrella sampling are in excellent agreement with the reference values obtained from independent simulations, for ΔT = ±15 K and ΔP = 100 bar (with respect to the simulated system). For larger systems, this range becomes smaller because the relative fluctuations of energy and volume become smaller. Without sufficient overlap, the performance of the method will become poor especially for nonlinear variations of the chemical potential.

Ion-Conductance and Solvation Behavior of Benzyl Trimethyl Ammonium Chloride in Aqueous Methanol Mixtures

Ion-conductance and solvation conduct associated with diverse electrolytes in solvents is recited to be shaped by numerous aspects like density, viscosity, dielectric constant of medium, ion-solvent relations and solvent-solvent actions. Ion-solvent interactions soothe the ion by solvating it. Conductance statistics and viscosity numbers of distant electrolytes is of use in analyzing the ion solvent relations and solvation behavior of the ions. Conductance and ion-solvation behavior of benzyl trimethyl ammonium chloride has been measured in aqueous methanol and aqueous dimethyl formamide of different composition in the temperature range of 283K to 318K. Limiting molar conductance dissociation constant of the ion pair, KC are figured using Fuoss-Kraus Limiting Law. 0 rise with percentage of water in the solvent fusion. KC value is highest in pure aqueous solvent. Walden product is highest in 20% aqueous-methanol mixture signifying that ion-solvent interactions are highest at this composition of solvent combination and Walden .product as a function of the specific ion-solvent interactions including structural effects.

5-Nitrosalicylaldehyde in aqueous co-solvent mixtures of methanol, ethanol, isopropanol and acetonitrile: Solubility determination, solvent effect and preferential solvation analysis

The equilibrium 5-nitrosalicylaldehyde solubility in methanol (1) + water (2), ethanol (1) + water (2), isopropanol (1) + water (2) and acetonitrile (1) + water (2) mixtures was determined by a shake-flask method from 273.15 K to 313.15 K under local pressure of 101.2 kPa. At the same mass fraction of methanol (ethanol, isopropanol or acetonitrile) and temperature, the mole fraction solubility of 5-nitrosalicylaldehyde was greater in (acetonitrile + water) mixture than in ethanol (1) + water (2), isopropanol (1) + water (2) and methanol (1) + water (2) mixtures. The relative importance of solute–solvent and solvent–solvent interactions upon the solubility variation was valued by using the linear solvation energy relationship analysis of solvent effect. The method of inverse Kirkwood–Buff integrals was used to study the preferential solvation on the basis of thermodynamic solution properties. The preferential solvation parameters for methanol, ethanol, isopropanol and acetonitrile were positive in the four mixtures in co-solvent-rich and intermediate composition, indicating that 5-nitrosalicylaldehyde was solvated preferentially by the co-solvent. It is conjecturable that in these regions 5-nitrosalicylaldehyde acts as a Lewis acid with the alcohols’ molecules; while for the acetonitrile + water mixture, the preferential solvation could be attributed to polarization effects. Moreover, the drugs’ solubility was mathematically represented via the Jouyban-Acree model acquiring the average relative deviations<6.03%.

Reductant-Induced Free Radical Fluoroalkylation of Nitrogen Heterocycles and Innate Aromatic Amino Acid Residues in Peptides and Proteins.

A series of fluoroalkylated cyclic λ3 -iodanes and their hydrochloride salts was prepared and used in a combination with sodium ascorbate in buffer or aqueous methanol mixtures for radical fluoroalkylation of a range of substituted indoles, pyrroles, tryptophan or its derivatives, and Trp residues in peptides. As demonstrated on several peptides, the aromatic amino acid residues of Trp, Tyr, Phe, and His are targeted with high selectivity to Trp. The functionalization method is biocompatible, mild, rapid, and transition-metal-free. The proteins myoglobin, ubiquitin, and human carbonic anhydrase I were also successfully functionalized.