Water-organic Solvent Systems Research Articles

Study of reactions in two-phase systems hydrolysis of triphenylmethyl chloride in water-organic solvent systems

The rate of hydrolysis was studied for triphenylmethyl chloride in water-organic solvent systems with an unstirred interface of a known area. The hydrolytic reaction was found to take place at the interface only. The temperature dependence of the reaction rate indicates that at lower temperatures (up to 60 °C) the rate-determining step is the chemical reaction, whereas at higher temperatures a deviation from the Arrhenius type dependence is observed, which along with the low activation energy value points to the diffusion as the governing phenomenon. The effect of salts added to the aqueous phase is consistent with the expected behaviour for the SN1 mechanism, but suprising is the inhibiting effect od some quaternary ammonium salts. In the study of the effect of the organic solvent, the reaction rate was found to correlate satisfactorily with the solubility of the organic solvent in water, but no correlation was established with the solubility of water in the solvent. From the results obtained it can be inferred that the reaction site is the laminary layer adjacent to the interface from the aqueous phase side.

Parameterization of hydrophobic properties of aqueous polymeric biphasic systems and water-organic solvent systems

Partition coefficients for a homologous series of dinitrophenylated amino acids with aliphatic side-chains have been determined in two aqueous polymeric Ficoll-dextran 70 and dextran 500-polyethylene glycol 6000 biphasic systems and in the systems formed by n-octanol and the aqueous phases of the above systems. The results afford an estimation of the free energy of transfer of a CH 2 group from one to the other phase of the systems examined. This parameter (Δ g tr CH 2 ) was taken as a measure of the hydrophobic character of an aqueous phase with respect to n-octanol. It was shown that when the partition of a set of homologues in two biphasic systems is correlated according to the known equation ln K i = a ln K o + b, where K i and K o are the partition coefficients for a given solute in the ith system and in the system chosen for reference, respectively, the parameter a is related to the Δ g tr 1 CH 2 and Δ g tr 0 CH 2 by a = Δ g tr 1 CH 2 /Δ g tr 0 CH 2 . This equation was used to determine the hydrophobic character of various organic solvents and that of the aqueous polymeric phases of the aqueous biphasic systems studied, and was found to be valid for comparison of the partition values determined in an aqueous polymeric biphasic system and in the water- n-octanol system. This seems to extend the possibilities of structure-activity relationships studies as the Ficoll-dextran aqueous biphasic system provides as promising a means for their study in biological chemistry as the water- n-octanol system in drug research.

Immobilized hydroxysteroid dehydrogenases for the transformation of steroids in water–organic solvent systems

The hydroxysteroid dehydrogenases: beta-HSDH, 20 beta-HSDH, and 3 alpha-HSDH, were immobilized on CNBr-activated Sepharose. The effect of various immobilization conditions on the activity recovery and stability were examined. The presence of cofactor during the immobilization reaction increased the activity recovery (40--60% of the total) and also led to materials highly stable in the presence of organic solvents. For example, beta-HSDH maintained 60% of its original activity two months after continuous use in the water--ethyl-acetate system. Kinetic experiments showed that the increase of the apparent Km values is poor and demonstrated that the organic solvent behaves as a weak inhibitor (ki greater than 0.2M) for the substrate. The immobilized enzymes lyophilized in the presence of sucrose had full activity restored even after several months storage at room temperature. Immobilized hydroxysteroid dehydrogenases were shown to be suitable for preparative transformation of steroids in water--organic solvent systems.

Time dependent phenomena during the solvent induced coil to helix transition of poly α l glutamic acid in aqueous mixed solvents

The variation of the conformation of poly (α l glutamic acid) (PLGA) in water-organic solvent mixtures has been studied as a function of time. These time dependent changes of the conformation have been observed in many water-organic solvent systems. The velocity of this phenomenon is very sensitive to the ionic strength of the solution. The origin of the time dependence of the conformation is discussed in relation with the preferential and absolute solvation of the polymer by the components of the solvent mixture.

Water as a nonpolar partition medium.

Coacervates have been suggested as models for cytoplasm since cytoplasm is also essentially an aqueous phase of water-protein-colloid complexes. This study on partition coefficient properties made use of coacervate phases as the nonpolar phases in equilibrium with polar water phases. The partition coefficients of four barbiturates were obtained, and their values correlated with those reported in the literature for systems using organic solvents as the nonpolar medium. These values also correlated with reported values for the absorption ranking of the barbiturates in the rat colon. The partition coefficients of theobromine and theophylline in gelatin-benzalkonium chloride coacervate systems were also found to correlate with the partition values reported in the literature for heptane-water and chloroform-water systems. Is is suggested that coacervate systems form a more realistic model for studying and predicting the absorption characteristics of drugs than do conventional organic solvent-water systems.

Absorption of radiation in the millimeter range by water-organic solvent systems

1. The absorption of electromagnetic radiation (λ 1.05 mm) by solutions of DMSO in water and DMSO and water in dioxane has been measured in the whole interval of relative concentrations. 2. The additivity of the absorption in systems containing dioxane, and its absence in the system H2O-DMSO, have been demonstrated. 3. The possibility of using the absorption of radiation in the millimeter range for the study of solvation in solutions has been shown.

On the acidity characteristics of decaborane(14) and its benzyl derivatives in organic solvent-water systems

On the acidity characteristics of decaborane(14) and its benzyl derivatives in organic solvent-water systems

ChemInform Abstract: DISTRIBUTION OF ACRYLIC AND ACETIC ACIDS IN WATER‐ORGANIC SOLVENT SYSTEMS

Chemischer InformationsdienstVolume 5, Issue 40 Article ChemInform Abstract: DISTRIBUTION OF ACRYLIC AND ACETIC ACIDS IN WATER-ORGANIC SOLVENT SYSTEMS A. HEYBERGER, A. HEYBERGERSearch for more papers by this authorD. BALCAROVA, D. BALCAROVASearch for more papers by this authorJ. BULICKA, J. BULICKASearch for more papers by this authorJ. PROCHAZKA, J. PROCHAZKASearch for more papers by this author A. HEYBERGER, A. HEYBERGERSearch for more papers by this authorD. BALCAROVA, D. BALCAROVASearch for more papers by this authorJ. BULICKA, J. BULICKASearch for more papers by this authorJ. PROCHAZKA, J. PROCHAZKASearch for more papers by this author First published: October 8, 1974 https://doi.org/10.1002/chin.197440113Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume5, Issue40October 8, 1974 RelatedInformation

Action of pancreatic lipase on monomeric tripropionin in the presence of water-miscible organic compounds

The addition of low concentrations of some water-miscible organic compounds (dioxane, acetonitrile, tert.-butanol, formamide) to an aqueous system induces a substantial increase of the activity of pancreatic lipase (EC 3.1.1.3) towards monomeric tripropionin. This effect is due to a rise of the maximum velocity ( V) of the reaction. K m becomes less favorable upon solvent addition with the result that, for all substrate concentrations lower than the saturating value, lipase activity passes by a maximum in a relatively narrow solvent concentration range. The fact that lipase is able to attack tripropionin monomers in organic solvent-water systems is confirmed by the complete disparation of the triglyceride after a 40% hydrolysis. The main product of the reaction is dipropionin. The finding that lipase can display a strong activity in the complete absence of substrate aggregates and interfaces is discussed in the light of current concepts concerning the mechanism of action of this enzyme. Hydrophobic interfaces and low concentrations of organic solvents have been reported to modify the structure of liquid water. The assumption is made that the modification favors the action of lipase on tripropionin monomers through a transconformation of the enzyme molecule or any other process.

Distribution of acrylic and acetic acids in water-organic solvent systems

Distribution of acrylic and acetic acids in water-organic solvent systems

Correlations between retention volumes and the interfacial tension of the two phases in liquid—liquid chromatography

Is is shown that the interfacial tension between the mobile and the stationary phases reflects the partition properties of the two phases, and this can be taken as a criteria of choice of the systems used in liquid—liquid chromatography. A semi-theoretical treatment shows that the Gibbs free energy of partition of solute between the two phases is quasi-proportional to the surface tension, provided that the solubility of each phase in the other is small. Such behaviour is observed with organic solvent—water systems for solvents that give a surface tension greater than 20–25 dynes/cm. As mixtures of mobile phases behave in the same way, the retention times in programmed gradient analysis can be predicted.

A statistical mechanical theory of unfolding of globular proteins induced by preferential binding of solvent components in water-organic solvent systems.

AbstractA statistical mechanical model was developed for use in connection with the problem of preferential binding of solvent components to proteins and of conformational transition in water‐organic solvent systems. The model is a statistical one for the conformational transition of globular proteins induced by the adsorption of solutes in the solution, considered as a nearest‐neighbor problem in statistical mechanics. Although a few illustrative examples are given, the actual interpretations of the experimental data using this theory are reserved for a later paper.

水-有機溶媒混合系におけるポリエチレンイミンのセルロースに対する吸着現象

Adsorption phenomena of polyethylenimine into cellulose in water-organic solvent system was investigated. As a result, minimum adsorption was observed in case of 1: 1 volume ratio of binary system, while maximum adsorption was in water or organic solvent alone. The measurement of viscosity showed the strong correlation to the retention. Therefore, from these results, it was pointed out that the adsorption phenomena of polyelectrolyte to porous material like cellulosic fiber in water-organic solvent system also could be well interpreted by so called “Jack in the box effect”.(1, 2)

Interaction of .beta.-lactoglobulin with solvent components in mixed water-organic solvent systems

Interaction of .beta.-lactoglobulin with solvent components in mixed water-organic solvent systems

Fractionation of particles and macromolecules in aqueous two-phase systems

The isolation from cells of particles such as nuclei, mitochondria, microsomes and chloroplasts is important in biochemical and physiological studies. Cell particles are separated according to size, density and form. Experiments showed that surface properties of particles could determine the fractionation in a liquid-liquid two phase system, complementing conventional fractionation techniques. Aqueous polymer two phase systems were used in preference to organic solvent-water systems. Enzymes and viruses may be distributed in these systems without loss of activity. The usefulness of the method is demonstrated with examples. Other properties of polymer two phase systems are also discussed.

The Electrical Behavior of Dodecylammonium Chloride in Water–Organic Solvent Systems

The Electrical Behavior of Dodecylammonium Chloride in Water–Organic Solvent Systems