Aqueous solutions and organic solvents

Ion exchange chromatography is usually carried out in aqueous solutions, because electrolytic dissociation in water splits the dissolved substances to be chromatographed into ions, which can then interact with the exchanger. Water also contributes to the dissociation of the functional groups and to the swelling of the exchanger, and in this way influences positively the rapid penetration of ions to the functional 

Ionic strength fi, a measure of the intensity of the electrical field due to the ions in the solution) strongly influences the nominal capacity of ion exchangers. High ionic strength (high concentration of buffers or salts) generally decreases the sorption of 

Chen et al. [110] applied heterocyclic cations (imidazole) and aromatic anions (/ -hydroxybenzoic acid) in buffers for determination of biogenic amines using 

2 Volatile or complex-forming buffers (special additives) 

Special additives are used to improve properties of mobile phases for chromatography in biochemical separations. Antimicrobial reagents are the most often applied a list of their characteristics is given in Ref. 98 (Table 10.8) and in Ref. 6 (Table 

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Anderson, N. H., Davis, S. S., James, M. and Kojima, I. (1983). Thermodynamics of distribution of p-substituted phenols between aqueous solution and organic solvents and phospholipid vesicles, J. Pharmaceut. Sci., 72, 443 148. 

Figure 13. Preparation of immobilized enzymes with different solubilities in aqueous solutions and organic solvents. Procedure A mixture of an enzyme (3 mg) and the polymer (10 mg) was incubated at pH 7.5 for 20 min. Ammonium phosphate (0.1 M, pH 7, 1 mL) was then added to react with the remaining active ester. After 20 min, the solution was ready for use, or lyophilization to give the immobilized enzyme as a powder to be used for reaction in organic solvents. Each gram of the polymer contains approximately 0.7 mmol of the active ester.

H8. Haviland, R. T., and Bieber, L. L., Scintillation counting of phosphorus-32 without added scintillator in aqueous solutions and organic solvents and on dry chromatographic media. Anal. Biochem. 33, 323-334 (1970). 

Jackson M and Mantsch HH. Conformation of the Peptide Hormone Somatostatin in Aqueous Solution and Organic Solvents. Vibrational Spectroscopy 1992b 3 323-326. 

Wang JM, Takeda A, Yang JT, and Wu CSC. Conformation of Concanavalin A and its Fragments in Aqueous Solution and Organic Solvent Water Mixtures. J Protein Cheml992 11 157-164. 

During the last two decades, the redox and acidity properties and the reactivity of substituted benzene radical cations in aqueous solution and organic solvents have been extensively studied pulse radiolysis, electrochemical techniques and photochemical techniques.[l,2,5-20]... 

This new extraction technology appears promising for effective processing with marked reduction in waste generation because no aqueous solutions and organic solvents are involved and phase-separation can be easily achieved by depressurization. Recently, the authors found a CO soluble TBP complex with nitric acid was very effective for dissolution of UO2 and U30g and extracted as U02(N03)2(TBP)2 in supercritical CO2 (SF-C02)(8-ii). 

Different separation and purification procedures have been proposed to isolate hemicelluloses from different raw materials. Extraction of hemicelluloses from different resources has been studied since a long time ago. Isolation of hemicelluloses using cost efficient extraction methods would be beneficial to increase the utilization of hemicelluloses. Alkaline aqueous solutions and organic solvents have been used to extract hemicelluloses from the original or delignified wood [holocellulose] [1,9,21,25,31,33,34,5 7]. 

Wijnen, f.W., Zavarise, S., Engberts, J.B.F.N. and Charton, M., Substituent effects on an inverse electron demand hetero Diels Alder reaction in aqueous solution and organic solvents cycloaddition of substituted styrenes to di(2 pyridyl) 1,2,4,5 tetrazine, /. Org. Chem., 1996,61, 2001-2005. 

Universal Solvation Model and Comparison of the Accuracy of Three Continuum Solvation Models, SM5.42R, SM5.43R, and C-PCM, in Aqueous Solution and Organic Solvents and for Vapor Pressures. 

Hydration. In partition studies of uranyl nitrate between aqueous solution and organic solvent (alcohols, esters, ethers euid ketones) It Is generally found that the water content of the organic phase Increases with uranyl nitrate concentration.por alcohols, the relation between the water content and uranyl nitrate concentration appears to be a complex function. Por esters, ethers, and ketones the relation Is linear except possibly at hl values of This relation may be expressed... 

Indicates mutual solubility of aqueous solution and organic solvent. 

Solvent extraction is subject to limitations imposed by the relatively unfavourable partition coefficients between aqueous solution and organic solvents that are shown by many organic acids. Diethyl ether alone will extract the most hydrophobic acids, whereas ethyl acetate improves the extraction of some of the more hydrophilic acids. The most suitable solvent can be selected by consideration of the acid or acids of interest [e.g. ether for phenyl-lactic acid, ethyl acetate for some other aromatic acids (Karoum et al, 1968)], although diethyl ether followed by ethyl acetate extraction, as employed by n any workers, provides a more comprehensive extraction system. Methyl acetate has been shown to increase the extraction of more hydrophilic acids such as citric acid (Lawson etal, 1976). 

A number of organic compounds, eg, acetylacetone [123-54-6] and cupferron [135-20-6] form compounds with aqueous actinide ions (IV state for reagents mentioned) that can be extracted from aqueous solution by organic solvents (12). The chelate complexes are especially noteworthy and, among these, the ones formed with diketones, such as 3-(2-thiophenoyl)-l,l,l-trifluoroacetone [326-91-0] (C4H2SCOCH2COCF2), are of importance in separation procedures for plutonium. 

Le Hung presented a general theoretical approach for calculating the Galvani potential Ajyj at the interface of two immiscible electrolyte solutions, e.g., aqueous (w) and organic solvent (s) [25]. Le Hung s approach allows the calculation of when the initial concentration (Cj), activity coefficients (j/,) and standard energies of transfer of ions (AjG ) are known in both solutions. 

Extraction from aqueous solutions into organic solvents can be achieved through different chemical reactions. Some may seem very complicated, but usually occur through a number of rather simple steps we assume this in making a model of the system. The subdivision of an extraction reaction into its simpler steps is useful for understanding how the distribution ratio varies as a function of the type and concentration of the reagents. Often these models allow equilibrium constants to be measured. 

Horse liver alcohol dehydrogenase is able to oxidise primary alcohols—except methanol—and to reduce a large number of aldehydes. Aqueous solution or organic solvents can be used [62]. As there are no new developments concerning this enzyme, the reader is referred to the review of Schreier [1]. 

A further problem is that many of the methods for plant cell-wall preparation, based upon insolubility in aqueous buffers, salt solutions, and organic solvents, undoubtedly remove, or detach, some of the molecules, present in the intact wall, which may have important, structural functions. 

Occasionally emulsions are formed in the extraction of aqueous solution by organic solvents, thus rendering a clean separation impossible. Emulsion formation is particularly liable to occur when the aqueous solution is alkaline, and when dichloromethane is the extracting solvent. The emulsion may be broken by any of the following devices, but in general its occurrence may be minimised... 

A procedure based on condensation with phenol and paraform (used as formaldehyde source) was developed to convert spent UNEX solvent (CCD, PEG-400, Ph2-CMPO, and FS-13) into a solid infusible resin for disposal. The resulting material is insoluble in aqueous alkali and acidic solutions and organic solvents. Incorporation of FS-13 in the cross-linked polymer was confirmed by physicochemical methods. Resistance of the cured resin to high temperatures was proven by thermogravimetry... 

The above statement concerning the effectiveness of the nitronium ion over a wide range of conditions has not always been accepted and, until recently, some workers held that the nitronium ion was not the effective electrophile in solutions of nitric acid in aqueous acids and organic solvents. It is unnecessary now to go into these arguments since the subject has been covered in a number of recent reviews (Ridd, 1971a Hoggett et al., 1971 Stock, 1976), and the... 

For the same reason as above, excess solvent molecules in the cavitation bubble also seriously limit the applicability of many volatile organic solvents as a medium for sonochemical reactions [2,25,26]. In fact, water becomes a unique solvent in many cases, combining its low vapor pressure, high surface tension, and viscosity with a high yield of active radical output in solution. Its higher cavitation threshold results in subsequently higher final temperatures and pressures upon bubble collapse. Most environmental remediation problems deal with aqueous solutions, whereas organic solvents are mostly used in synthesis and polymer modifications processes. 

Organosolv. Organosolv lignins are obtained as relatively low-molecular-weight entities by treatment of plant tissue with aqueous solutions of organic solvents, normally containing trace amounts of mineral acids (44) Solvents include ethanol, methanol, butanol, acetic acid, ethyl acetate, phenol, etc. To date, this approach has not been commercialized due to the quantities of organic solvents consumed and the low quality of the pulp fiber obtained. 

It is well known that silver (I) can be reduced to the metallic state with various organic substances and thus agitation of silver (I) with some extractants may reduce it. In the literature, the solvent extraction-reduction process possesses metallic ions were extracted form an aqueous solution to organic solvents and then the ions were reduced in the organic phase by reductant or radiation. In this work, we report a new strategy to prepare wicker-shaped silver. The primary amine N1923 is used as extractant and reductant. 

In order to also obtain information about the kinetics of the extraction process, six 2.5 g portions of this sludge were suspended in aqueous solutions or organic solvents in Erlenmeyer flasks and shaken for 1, 3, 7, 9, 13, and 24 hours respectively (sludge/solution ratio 1 10 w/v). 

Amine N-oxides, phosphine oxides, arsine oxides, and related ligands. The prototypical system for extraction of the uranyl ion from aqueous solution into organic solvent is tributylphosphate in hydrocarbons such as kerosene. This has stimulated interest in understanding the coordination chemistry of actinyl ions with P=0 (and related) functional groups in order to optimize extraction efficiency or discrimination among actinides to be separated. Of all classes of neutral group 16-atom donor ligands, phosphine oxide adducts are the most common examples of complexes of transuranic elements (Np, Pu). 

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