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Organic aqueous

One problem limiting the consideration of salt extractive distillation is the fact that the performance and solubility of a salt in a particiilar system is difficult to predict without experimental data. Some recent advances have been made in modeling the X T.E behavior of organic-aqueous-salt solutions using modified UNIFAC, NRTL, UNIQUAC, and other approaches [Kumar, Sep. Sci. Tech., 28(1), 799 (1993)]. [Pg.1319]

Nature of aqueous feed Organic-aqueous ratio required Permissible settler flow rate, U.S. gal/(min-fd) borizontal area... [Pg.1471]

Type of eluent Organic Polar organic Organic, aqueous, and mixtures Aqueous... [Pg.273]

When the range of chemieal types is restricted, regular behavior is often observed. For example, one might choose to study a series of hydroxylic solvents, thus holding approximately constant the H-bonding capabilities within the series. This is a motivation, also, for solvent studies in a series of binary mixed solvents, often an organic-aqueous mixture whose composition may be varied from pure water to pure organic. Mukerjee et al. defined a quantity H for hydroxylic and mixed hydroxyiic-water solvents by Eq. (8-17). [Pg.401]

It is important to make the distinction between the multiphasic catalysis concept and transfer-assisted organometallic reactions or phase-transfer catalysis (PTC). In this latter approach, a catalytic amount of quaternary ammonium salt [Q] [X] is present in an aqueous phase. The catalyst s lipophilic cation [Q] transports the reactant s anion [Y] to the organic phase, as an ion-pair, and the chemical reaction occurs in the organic phase of the two-phase organic/aqueous mixture [2]. [Pg.258]

Burger and coworkers (5) in 1952 reported that some distribution coefficients for Pu022+ in organic-aqueous systems at lighted conditions were different from those observed for dark conditions, and those authors believed that some Pu022+ had been photochemically reduced. That reduction was confirmed by others (6) in 1965, and in 1969 a report suggested that most aqueous plutonium reactions were affected by light (7 ). [Pg.264]

The enantioselective reduction of alkyl 3-oxobutanoates by carbonyl reductase (SI) from C. magnoliae was also performed in organic-aqueous two-phase reaction system (Figure 8.15) [llc,d]. [Pg.211]

Fortunately, as the reaction is transferred from a purely organic solvent system to mixed organic-aqueous media, which are employed in most RP-HPLC separations, the apparent multiplicity of maxima in the time profile of the intensity dependence seems to be suppressed or to collapse to a reasonably simple biexponential-like dependence. As shown in Figure 11, simply changing the solvent from ethyl acetate to 95% aqueous acetonitrile and the catalyst from triethylamlne to imidazole produces a single maximum profile, one that is more easily modeled mathematically, as defined in Equation 4 ... [Pg.143]

Special mention must be made of the control of the regioselectivity of the ring opening of AT-acylaziridines 38 at an organic-aqueous interface (Scheme 26) [36]. The fatty acid chains and the phenoxy substituent will orient the substrate such that the unsubstituted aziridine carbon atom points to the aqueous layer... [Pg.108]

Researchers studying polypeptide and polypeptide hybrid systems have also processed vesicles using two solvents. This method usually involves a common organic solvent that solubilizes both blocks and an aqueous solvent that solublizes only the hydrophilic block. The two solvents can be mixed with the polypeptide or polypeptide hybrid system at the same time or added sequentially. The choice of organic solvent depends heavily upon the properties of the polypeptide material, and commonly used solvents include dimethylformamide (DMF) [46, 59], methanol (MeOH) [49], dimethyl sulfoxide (DMSO) [50, 72], and tetrahydrofuran (THF) [44, 55]. Vesicles are usually formed when the organic solvent is slowly replaced with an aqueous solution via dialysis or removed through evaporation however, some vesicles have been reported to be present in the organic/aqueous mixture [49]. [Pg.126]

OS 43] [R 14] [P 32] Using a three-liquid layer (water/oil/water) flow instead of a two-liquid layer flow at constant channel dimensions decreases the liquid lamellae width and doubles the absolute value of the organic/aqueous interface. As a consequence, mass transport is facilitated compared with the two-flow configuration. Hence it was found that a much higher yield was obtained for the three-liquid layer flow when performing experiments of both flow configurations imder the same experimental conditions (210 s, 0.2 pi min room temperature, 300 W, > 300 nm... [Pg.477]

An important problem in emulsified organic-aqueous systems is that of scale-up, which is concerned with the realization of stable emulsions and the separation of phases after the reaction. The use of biphasic membrane systems that contain the enzyme and keep the two phases separated is likely to solve this problem. In the case of 5-naproxen an ee of 92% has been demonstrated without any decay in activity over a period of two weeks of continuous operation. A number of examples of biocatalytic membrane reactors have been provided by Giorno and Drioli (2000) and include the conversion of fumaric acid to L-aspartic acid, L-aspartic acid to L-alanine, and cortexolone to hydrocortisone and prednisolone. [Pg.162]

Most studies of ORR catalysis by metalloporphyrins have been carried out using water-insoluble catalysts absorbed on a graphite electrode in contact with aqueous solution. In a limited number of cases, four other approaches have been used catalysts imbedded in an inert film (i.e., Nafion or lipid) on the electrode surface self-assembled monolayers of catalysts catalysts in aqueous or mixed organic/aqueous solutions in contact with an electrode and catalysis in mixed aqueous/organic medium using... [Pg.647]

To evaluate the contribution of the SHG active oriented cation complexes to the ISE potential, the SHG responses were analyzed on the basis of a space-charge model [30,31]. This model, which was proposed to explain the permselectivity behavior of electrically neutral ionophore-based liquid membranes, assumes that a space charge region exists at the membrane boundary the primary function of lipophilic ionophores is to solubilize cations in the boundary region of the membrane, whereas hydrophilic counteranions are excluded from the membrane phase. Theoretical treatments of this model reported so far were essentially based on the assumption of a double-diffuse layer at the organic-aqueous solution interface and used a description of the diffuse double layer based on the classical Gouy-Chapman theory [31,34]. [Pg.450]

On the other hand, two-phase systems have potential disadvantages. Biocatalyst inhibition or denaturation may occur in contact with organic solvent dissolved in the aqueous phase or at the organic-aqueous interface. The system may be complex and inflammable. [Pg.555]

When an organic phase is added to the medium, transfer of a poorly water-soluble organic component from organic to aqueous phase is observed across the liquid-liquid interface. A sparingly water-soluble substrate may make up the organic phase, or be dissolved in an apolar organic solvent. This can affect the transfer over the organic-aqueous interface. [Pg.556]

On the other hand, biocatalyst stability can be affected by the presence of organic-aqueous interface. In our previous work [25], we studied the effect of interface with octane on the lipoxygenase stability in an octane-buffer pH 9.6 biphasic system. This loss in activity is more pronounced than that observed in the aqueous system. During lipoxygena-tion, the active enzyme concentration [E] in the aqueous phase of our biphasic bioreactor was ... [Pg.560]

TABLE 2 Enzyme Preparations Used in Organic-Aqueous Diphasic Media... [Pg.565]

Lipase (EC 3.1.1.3, triacylglycerol acylhydrolase), both substrate (ester) and product (fatty acid), are poorly water soluble. The reaction occurs at the organic-aqueous interface [8,43,83,84]. [Pg.568]

The lipases demonstrated very high stability in media partially or totally composed of organic solvent. In such media, the lipases catalyze esterification, transesterification, and resolution of enantiomers [19,45,75,97-100]. Nevertheless, several biphasic systems (organic-aqueous) are used for hydrolysis of lipid and fats [7,34,101]. Kinetic studies in biphase media or in inverted micelles demonstrate that the lipase behavior is different... [Pg.569]

The present section deals with the improvement in the performance of biocatalysis when carried out in organic-aqueous biphasic systems. Such systems are very useful in equilibrium reactions and conversion yield where substrates and products can be dissolved and drawn into different phases. Subsequently the synthesis in the reactive aqueous phase is allowed to continue. [Pg.575]

Yang and Russell [7] made comparison of lipase-catalyzed hydrolysis in three different systems organic, biphasic, and reversed micelles. They affirmed that water content is an important factor that distinctly affects every system. Their results demonstrated that activity of lipase in organic-aqueous biphasic media was lower than that obtained in reversed micelles. However, better productivities were obtained in biphasic media, which were the most suitable environment. [Pg.576]

Many interesting biocatalytic reactions involve organic components that are poorly water-soluble. When using organic-aqueous biphasic bioreactor, availability of poorly water-soluble reactants to cells and enzymes is improved, and product extraction can be coupled to the bioreaction. Many applications in two-phase media can use the existing standard-type bioreactors, such as stirred-tank, fluidized-bed, and column reactors with minor adjustments. [Pg.579]

As proven in this review and other papers, organic-aqueous biphasic media have been useful in many areas of biocatalysis applications. We summarize the potential advantages in carrying out biocatalysis in biphasic systems ... [Pg.581]

Most small organic molecules are soluble in mixed organic-aqueous solvents and can be easily analyzed using RPLC. However, there are some polar compounds which are not soluble in typical RPLC solvent systems or are unstable in an aqueous mobile phase system. These compounds can be analyzed on an RPLC column with a nonaqueous solvent system. This technique is called "nonaqueous reversed phase chromatography" (NARP).20-21 The NARP technique is primarily used for the separation of lipophilic compounds having low to medium polarity and a molecular weight larger than... [Pg.148]


See other pages where Organic aqueous is mentioned: [Pg.1215]    [Pg.564]    [Pg.300]    [Pg.1471]    [Pg.58]    [Pg.271]    [Pg.54]    [Pg.55]    [Pg.204]    [Pg.29]    [Pg.58]    [Pg.274]    [Pg.37]    [Pg.139]    [Pg.64]    [Pg.653]    [Pg.720]    [Pg.821]    [Pg.460]    [Pg.559]    [Pg.564]    [Pg.567]    [Pg.568]   
See also in sourсe #XX -- [ Pg.59 , Pg.60 ]




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Absorption of Organic Molecules from Aqueous Solutions

Absorption organic molecules from aqueous

Adsorption of Ionized Organic Compounds from Aqueous Solutions to Charged Mineral Surfaces

Aqueous Solubility and Henry’s Law Constants of Organic

Aqueous Solubility of Inorganic and Organic Compounds

Aqueous Systems with Additional Organic Solvent

Aqueous Systems without Additional Organic Solvent

Aqueous media organic synthesis

Aqueous mixtures, kinetics of organic

Aqueous mixtures, kinetics of organic reactions in water and

Aqueous organic solution permeation

Aqueous organic solvents

Aqueous solutions and organic solvents

Aqueous solutions of organic

Aqueous solutions of organic compounds

Aqueous solutions organic chemicals

Aqueous-based cleaning agents containing water soluble organic components

Aqueous-organic biphasic reactions

Aqueous-organic interphase

Aqueous-organic two-phase reaction

Aqueous-phase chemistry organic

Aqueous/organic cosolvent systems

Bioreduction in Biphasic Aqueous-Organic Systems

Biphasic aqueous—organic systems

Biphasic catalysts aqueous organic solvents, recyclable systems

Biphasic organic-aqueous

Chemistry On Water - Organic Synthesis in Aqueous Suspension

Comprehensive Organic Reactions in Aqueous Media, Second Edition, by Chao-Jun

Cross-coupling reactions aqueous organic solvents

Effects of Organic Cosolvent in Mixed Aqueous Solution on the Reaction Rates

Equilibria in Aqueous and Organic Solutions

First Dissociation Constants of Organic Acids in Aqueous Solution at

Gradient elution mode aqueous-organic mobile phase

Higher aqueous-organic biphasic system

Hydroformylation of Olefins in Aqueous-Organic Biphasic Catalytic Systems

Interface aqueous-organic

Kinetic medium effects on organic reactions in aqueous colloidal solutions

Ligands for Aqueous-Organic Biphasic Catalysis

Micelles, aqueous, and similar assemblies, organic reactivity

Micro-aqueous organic reaction system

Microemulsions, aqueous organic solvents

Microemulsions, aqueous organic solvents solubilization

Mixed Aqueous-Organic Solvents

Monophasic aqueous-organic systems

Multiphasic aqueous-organic reaction

Organic Reactivity in Aqueous Micelles and Similar Assemblies

Organic Synthesis with Enzymes in Non-Aqueous Media. Edited by Giacomo Carrea and Sergio Riva

Organic aqueous corrosion

Organic aqueous tunable solvents

Organic aqueous tunable solvents OATS)

Organic aqueous two-phase

Organic chemistry aqueous media

Organic compounds aqueous solutions

Organic compounds from aqueous phase

Organic compounds in aqueous solution

Organic compounds in aqueous systems

Organic compounds solubility, aqueous at high temperature

Organic compounds, aqueous solubility

Organic compounds, aqueous solubility enhancement

Organic matter aqueous

Organic molecules from aqueous solutions

Organic molecules from aqueous solutions absorption)

Organic solutes adsorption, from aqueous

Organic solutes adsorption, from aqueous Subject

Organic solutes adsorption, from aqueous adsorbent characteristics

Organic solutes adsorption, from aqueous adsorptive characteristics

Organic solutes adsorption, from aqueous controlling factors

Organic solutes adsorption, from aqueous dilute solutions

Organic solutes adsorption, from aqueous electrostatic interaction

Organic solutes adsorption, from aqueous ionic strength

Organic solutes adsorption, from aqueous solution

Organic solvent-aqueous electrolyte

Organic-Aqueous Biphasic Systems General Considerations

Organic-aqueous partitions

Organic-aqueous two-phase system

Organics removal from aqueous phase

Partition of a Carboxylic Acid between the Aqueous and Organic Phases

Permeate aqueous organic solution

Phase transfer reactions, aqueous organic solvents

Potential differences between organic liquids and aqueous solutions

Preparation of Aqueous and Organic Scintillation Fluid

Preparative-scale Kinetic Resolution Using Aldolase Antibodies in a Biphasic Aqueous-Organic Solvent System

Recyclable systems, aqueous organic solvents

Residual organic compounds fractionation from aqueous

Reverse phase transfer, aqueous organic solvents

Self-organization, aqueous

Solubilization, aqueous organic solvents

Sorption of Organic Compounds from Aqueous Solutions

Subcritical water, aqueous organic solvents

Subcritical water, aqueous organic solvents research background

Supercritical water, aqueous organic solvents

Supramolecular Gels in Aqueous and Polar Organic Media

Volatile organic compounds removal from aqueous solutions

Water and aqueous mixtures, kinetics of organic reactions

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