Comparison of Partition Chromatographic Parameters of Lipophilic Organic Electrolytes for Solvents of Various Donor-Acceptor Properties. V. Phenols in Systems of the Type Organic Solvent/Formamide

Abstract

R_M values of a number of phenols (cresols, xylenols, chlorophenols, hydroxynaphthalenes) have been determined for numerous solvent systems of the type, weakly polar solvent/formamide. To determine a quantitative scale of extraction strengths, R_M -solvent spectra have been plotted using a modified method of Rohrschneider and Littlewood. 2-Methylquinoline, used in previous investigations as a reference solute for nitrogen bases, has been found unsuitable for phenols, and much more regular spectra have been obtained with 1-naphthol as the reference compound. The experimental results indicate that the extraction strengths of solvents cannot be characterized by a single series. Much more satisfactory results are obtained when two series are determined, based on the partition chromatographic parameters of two solutes of opposite H-bonding properties, e.g., 2-methylquinoline and 1-naphthol. For many of the phenols, linear R_M -solvent spectra are obtained when the solvents on the abscissa are arranged to give a linear spectrum for 1-naphthol, so that the spectra can be used to predict chromatographic parameters of related solutes.     

EXTRACTION OF METAL IONS WITH DZEHPA FROM MIXED AQUEOUS-ORGANIC MEDIA

Extraction of metal ions from the aqueous-organic solution containing dimethyl formamide(DMF), dimethyl sulfoxide(DMSO) and acetonitrile(AN) was investigated by using di-2-ethylhexyl-phosphoric acid(D2EHPA) as an extractant. The organic phase was a binary solution of D2EHPA and n-hexane, or D2EHPA and toluene, while the polar phase was a three component solution of metal salt, non-aqueous solvent and water. The extracted metal ions were Cr(III), Fe(III), Al, Cu, Ni, Co(II), Mg and Ag.

The extraction behaviors may be explained by the solvation ability of non-aqueous solvents, the decrease in distribution of the extractant and extract into the organic phase, and the interaction between the extractant and non-aqueous solvents due to the dissolution of non-aqueous solvents in the organic phase.     

Extraction Equilibria of Butyric Acid with Organic Solvents

Abstract

Fourteen solvents (five with a tertiary amine and different diluents, four C8-C18 alcohols, dibutylether, two hydrocarbons, and two vegetable oils) have been tested for the extraction of butyric acid. The highest distribution coefficient for butyric acid is shown by solvents with tertiary amines. A ternary solvent with amine extractant, n-alkanes as diluent, and higher alcohol as modifier can be advantageous in this procedure. Amines enable the extraction of acid at a pH above the pK _a value up to about pH 5.6. With an increase of the molecular weight of alcohol, the value of the distribution coefficient decreases. Its value for pure alcohols is independent of the concentration of acid in the aqueous phase. Equilibrium data suggest that the stoichiometry of the acid-alcohol complex is 2:1, and only undissociated acid is extracted.     

A Kinetics and Mechanism Investigation of the Nucleophilic Substitution Reaction of <Emphasis Type="Italic">α-</Emphasis>Chlorododecyl Carboxylate with Trimethylamine

A nucleophilic substitution reaction was developed to synthesize the zwitterionic surfactant using a renewable natural fatty acid rather than a petroleum derivative as the raw material. The kinetics and mechanism of the nucleophilic substitution reaction of trimethylamine α-chlorododecyl carboxylate with trimethylamine were investigated in protic and dipolar aprotic solvents including water, ethanol and N, N-dimethyl formamide. The rate equations were derived using initial rates and the activation parameters in different solvents were determined empirically and compared with each other to obtain important information about the reaction mechanism. The overall second-order reaction number and the negative activation entropy supported a bimolecular nucleophilic substitution (S_N2) mechanism, combined with the pseudo-first-order kinetics for each reactant. The experimental results also showed that the reaction reactivity diminishes with the decrease in polarity of protic solvents. The typical dipolar aprotic solvent dimethyl formamide distinctively promoted the reaction in. This fact was successfully explained by the solvation rule for S_N2 reactions.     

Influence of Some Organic Additives on the Extractive Separation of Americium(III) by Sulfoxides

Abstract

The solvent extraction behavior of americium(III) from aqueous nitrate media by two long-chain aliphatic sulfoxides has been examined systematically in the presence of several water-miscible organic solvents to study their possible synergistic effect on metal ion extraction. Methanol, ethanol, n- and isopropanol, n-butanol, dioxane, acetone, as well as acetonitrile, were employed as the organic component of the mixed (polar) phase. These additives affected the extraction to varying degrees. Extractability of Am increased 5 to 10-fold with increasing concentration of some of these additives, with the maximum enhancement being observed in the presence of acetone or acetonitrile. However, alcohols are generally very poor in this respect. Possible reasons for such behavior are briefly discussed. The distribution of several common contaminants was also investigated at the optimum condition for americium extraction.     

Extraction of Candida rugosa lipase from aqueous solutions into organic solvents by forming an ion‐paired complex with AOT

Candida rugosa lipase was extracted from aqueous solutions into organic solvents by forming an ion‐paired complex with sodium bis(2‐ethylhexyl)sulfosuccinate (AOT). The optimal aqueous pH for lipase recovery was 4.5 and the optimal CaCl₂ concentration was 10 mmol dm^?3. The lipase recovery decreased with increasing aqueous enzyme concentration but increased with increasing AOT concentration in the organic phase. The presence of polar co‐solvents in the aqueous phase did not obviously improve the lipase recovery, which was also little influenced by the type of hydrophobic organic solvent used for solubilising AOT. Surprisingly, no detectable activity of the ion‐paired C. rugosa lipase was observed for both the esterification of lauric acid with 1‐propanol in isooctane and the hydrolysis of olive oil in isooctane containing an appropriate amount of water. The ion‐paired C. rugosa lipase mediated the enantioselective crystallisation of racemic ketoprofen in isooctane, indicating the feasibility of using it as a chiral mediator for the enantioseparation of hydrophobic racemic compounds in organic systems. Copyright © 2006 Society of Chemical Industry     

Toxicity of organic solvents to fatty acid forming bacteria

The inhibition of fatty acid formation in the anaerobic digestion of synthetic swine manure by several solvents has been studied. The solvents tested were commonly used for the recovery of acetic acid from dilute aqueous solutions. Negligible inhibition was observed with kerosene and tri-octyl phosphine oxide. The latter compound was added as a carrier to increase the solubility of fatty acids in the organic phase. The most toxic solvent tested was di-isopropyl ether with Aliquat 336 added as a carrier. The use of published oral LD₅₀ values for rats was found to provide a qualitative estimate of the bacterial inhibition by a solvent when divided by the water solubility of the solvent.     

Use of Empirical Correlations to Determine Solvent Effects in the Solvolysis of S-Methyl Chlorothioformate

The specific rates of solvolysis of S-methyl chlorothioformate (MeSCOCl) are analyzed in 20 solvents of widely varying nucleophilicity and ionizing power at 25.0 °C using the extended Grunwald-Winstein Equation. A stepwise S_N1 (D_N + A_N) mechanism is proposed in the more ionizing solvents including six aqueous fluoroalcohols. In these solvents, a large sensitivity value of 0.79 towards changes in solvent nucleophilicity (l) is indicative of profound rearside nucleophilic solvation of the developing carbocation. In twelve of the more nucleophilic pure alchohols and aqueous solutions, the sensitivities obtained for solvent nucleophilicity (l) and solvent ionizing power (m) are similar to those found in acyl chlorides where an association-dissociation (A_N + D_N) mechanism is believed to be operative.     

Phase behavior of laundry surfactants in polar solvents

Laundry surfactants are usually mixtures of ionic and nonionic detergents that exhibit a complex phase behavior. Here the ternary phase behavior of an isotropic and a liquid crystalline (LC) surfactant mixture has been examined in water/solvent systems. The size of the LC area in the ternary phase diagram was correlated to solvent parameters including the dielectric constant and the Gordon cohesiveness parameter. The Gordon parameter was found to have a linear relationship with the amount of solvent needed to go from an LC to an isotropic state over a wide range of solvents from polar to apolar. For solvents in which no surfactant aggregation (micellar or inverted micellar) is expected, the size of the LC area is linear with the reciprocal of the dielectric constant of the solvent. On diluting practical detergent liquids with water, a large LC area can be avoided by using solvents with a relatively low dielectric constant and with a relatively low molecular weight. The aggregated state of the surfactant mixtures in the isotropic regions of the phase diagram was studied using the solvatochromic fluorescent probe Nile Red. In the water corner of the phase diagram, the surfactants are aggregated into micelles. In strongly polar solvents, such as glycerol, ethylene glycol, formamide, and ethanolamine, the surfactants are also aggregated into micelles. In somewhat less polar solvents, such as methanol, ethanol, and t-butanol, the surfactant molecules are randomly distributed. In the surfactant-rich corner of the phase diagram of the isotropic mixture, the surfactant forms inverted micelles. An inverted micelle-to-micelle transition could be observed on dilution in ethylene glycol as a discontinuity in the trend of the Nile Red fluorescence maxima.     

Photofading Kinetics and Thermodynamics of Some Azo Disperse Dyes in Amide Solvents under the Influence of Far Ultra–violet Radiation

The paper reports some kinetic measurements of photofading of some 4′-substituted 4–diethylaminoazobenzenes in formamide, N–methy/formamide, N, N–dimethy/formamide, N–methylacetamide and N, N–dimethyiacetamide. The observed Hammett p–values suggest a reductive pathway, as confirmed by the presence of anilines among the fading products. The free energies of solvation of the dyes in the various solvents have also been calculated by measuring the distribution coefficients of the dye between the amide solvent and n–hexane, as immiscible standard solvent. A fair linear correlation exists between the observed rate constants and the free energies of transfer, suggesting the possibility that photofading rate increases with increasing solvation of dye.     

Extraction of Phenol Using Trialkylphosphine Oxides (Cyanex 923) in Kerosene

Abstract

A group of extractants based on phosphine oxides have been reported as an alternative to conventional polar solvents for phenol liquid-liquid extraction. Among phosphoryl extractants, Cyanex 923 (a mixture of four trialkylphosphine oxides, alkyl = normal, C₆, C₈) has proved to combine high extraction efficiency and low water solubility (1, 2), obviating the necessity of removing the solvent from the aqueous raffinate, a need asso- ciated with the use of methyl isobutyl ketone and isopropyl ether, the solvents most widely employed for this application (3, 4).     

Concentrated phases of an ionic surfactant (Aerosol OT) in polar solvents

We have studied concentrated phases of Aerosol OT (AOT) in polar (water, ethylene glycol, formamide, N,N-dimethylformamide) and apolar (isooctane) solvents. We investigated two surfactant volume fractions (φ = 0.2 and φ = 0.6) with small angle x-ray scattering (SAXS), rheology and electrical conductivity experiments. AOT self-assembles differently depending on solvent type and concentration. SAXS experiments show that the AOT/water system displays a lamellar phase. In the other cases, only formamide displays a lamellar phase for φ = 0.6. The other solvents (and formamide at φ = 0.2) promote the self-assembly of AOT in other microstructures. The SAXS spectra display correlation peaks consistent with a disordered array of cylindrical aggregates. The microstructure of the AOT/isooctane system at φ = 0.2 is that of an arrangement of spherical aggregates. The results are explained in terms of surfactant packing models and solvent properties. For instance, the ability of ethylene glycol to form hydrogen bonds with AOT promotes the formation of cylindrical aggregates by increasing the area per surfactant polar head. As N,N-dimethylformamide is slightly miscible in hydrocarbons it increases the volume of the surfactant tail promoting reverse structures.     

Comparison of Partition Chromatographic Parameters of Lipophilic Organic Electrolytes for Solvents of Various Donor-Acceptor Properties. VI. 4-Pyridyl Alkyl Ketones and 4-Pyridyl Alkyl Alcohols in Aqueous and Formamide Systems

Abstract

R_M -solvent spectra have been determined for two homologous series of solutes: 4-pyridyl alkyl ketones and 4-pyridyl alkyl alcohols. The substitution of the carbonyl group by the secondary hydroxyl group had little effect on the extraction strength of the solvents of class N and A; however, for electron donor solvents a marked increase of extraction was observed, the shift of the position of solvents in the spectra being approximately constant for aqueous systems. Scales of extraction strengths for various reference compounds have been compared.     

INTERFACIAL TENSION ESTIMATION IN ORGANIC/AQUEOUS SYSTEM

ABSTRACT

Linear solvation energy relationships are used to estimate the interfacial tension at solvent/water interfaces for systems containing ‘dry’ and ‘wet’ solvents. The correlation analysis works also in the systems containing Primene 81R and metal salts. The models

?^° = a - b, log x_S,W - b₂ log x_W,S and

?^° = a - b log (x_S,W + x_W,S)give good estimation of the interfacial tension. In the systems containing Primene 81R the surface pressure is correlated with solvent parameters according to relation ?°-7 = a + D7r*=c/3     

Evidence for 1La, 1Lb Dual State Emission in 1-naphthol and 1-methoxynaphthalene Fluorescence in Liquid Solutions

The steady-state fluorescence spectra of 1-methoxynaphthalene and 1-naphthol were measured in pure organic solvents and in binary mixtures of water and several organic solvents. The 1-isomers exhibited a much larger fluorescence Stokes-shift than the corresponding 2-isomers. The emission spectra of 1-methoxynaphthalene and 1-naphthol in pure nonpolar organic solvents exhibited roughly the same structured spectral features, while the fluorescence spectra in water and formamide exhibited much broader red-shifted and less structured spectral features. In accord with previous observations, we attribute these spectral changes to two emitting states, ¹L_b and ¹L_a, whose relative fluorescence intensities are sensitive to solvent polarity. Our analysis of the fluorescence spectra of 1-naphthol and 1-methoxynaphthalene by Pekarian functions have demonstrated that the ¹L_a state becomes the dominant emitting state in polar solvents. In addition, the ¹L_a state was found to be further stabilized in hydrogen-bond-donating solvents. In contrast to previous suggestions, the onset of the excited-state proton transfer reaction from 1-naphthol occurred at higher solvent polarities than those required for the establishment of a dominantly ¹L_a emitting state.     

Extraordinary swelling behavior of poly(AMPS) organogel in solvent/DMSO binary mixed media

The present article deals with super‐swelling behavior of crosslinked homopolymer of 2‐acrylamido‐2‐methylpropane sulfonic acid, poly(AMPS), in binary mixtures of dimethyl sulfoxide (DMSO) and various polar solvents including water, mono‐, and polyhydric alcohols, and amide solvents such as N‐methyl pyrrolidone. Extraordinary phase transition sequences including a new unusual swelling phenomenon, referred to as “overentrant” swelling, was observed for this polymeric organogel in the solvent/DMSO mixtures. The swelling behaviors were preliminarily explained based on the major interactions involved in the solvation process and dielectric constant of the swelling media. It was established that the “overentrant” region of the swelling profiles was progressed with the increase of dielectric constant of the mixed solvent media. The overentrant region was disappeared with partial replacement of AMPS units with acrylic acid. This was taken as an additional practical evidence for a major role of the sulfonic acid as the main interactive group involved in the solvation process. The unusual phase transitions were also explained via a semiquantitative approach based on the Gutmann's acceptor number and donor number values to emphasis on the key effect of dissociation degree of the sulfonic acid group (as a function of the solvent type and composition) on the swelling behaviors. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

High Molecular Weight Pyridine Amines as Solvents for Uranium(VI) and Its Separation from Thorium

Abstract

Three high-molecular-weight pyridine amines, 5-(4-pyridyl)nonane, 2-hexylpyridine, and diphenyl-2-pyridylmethane, have been studied as components of solvent extraction systems. Results are presented to show the dependence of the uranium extraction coefficient (D _a ^o = [U_org]/[U_aq]) on equilibrium concentrations of hydrochloric, nitric, and sulfuric acid solutions with and without thiocyanate ions. The optimal conditions for the extraction have been carefully selected from an extensive and critical investigation of the various factors involved; e.g., the effects of diluents, concentration of the mineral acids, thiocyanate ions, salting and complexing agents, and the concentration of the solvents. The extraction mechanism and composition of the extracted complexes of uranium have been studied from partition and slope-analysis data. The results obtained give an orderly picture of the mechanism of extraction of uranium thiocyanate complexes (partly in relation to the hydration and solvation of the compounds extracted). Anomalous extraction behavior was observed at solvent concentrations greater than 0.05 M. The results have been interpreted on the basis of the formation of micelles of the salt molecules of the solvents. It has been shown that these pyridines will extract the metal efficiently and reversibly from dilute acid chloride, nitrate, and sulfate solutions containing thiocyanate. Common salts have no depressing effect on extraction. Distribution coefficients and separation factors of several metal ions, with respect to uranium(VI), are reported for the three mineral acid systems, and a method for the separation of thorium-234 from uranium is also described.     

The Mechanism of Phase Separation of Polymers in Organic Media—Apolar and Polar Systems

Abstract

The phase separation properties of nine apolar and 15 polar systems, each comprising two polymers dissolved in one organic solvent, were examined in the light of recent developments in surface thermodynamics of polar components. A clear correlation existed between the sign of the total interfacial free energy of interaction of the system and the phase separation (or miscibility). Conversely, some of the phase separation results could be used to estimate the electron-donor surface tension parameters of methyl ethyl ketone and tetrahydrofuran.