Solvents miscibility with water

In certain cases where the heteroaromatic amine is insufficiently soluble in aqueous acid, it can be dissolved in the minimum volume of an organic solvent miscible with water. Dilute mineral acid and a solution of sodium nitrite are then added. An example is the diazotization of 2-phenyl-3-amino-4-acetyl-5-methyl-pyrrole (Dattolo et al., 1983). 

Addition of a cosolvent is an alternative mechanism to increase contaminant solubility in an aqueous solution. When a contaminant with low solubility enters an aqueous solution containing a cosolvent (e.g., acetone), the logarithm of its solubility is nearly a linear function of the mole fraction composition of the cosolvent (Hartley and Graham-Bryce 1980). The amount of contaminant that can dissolve in a mixture of two equal amounts of different solvents, within an aqueous phase, is much smaller than the amount that can dissolve solely by the more powerful solvent. In the case of a powerful organic solvent miscible with water, a more nearly linear slope for the log solubility versus solvent composition relationship is obtained if the composition is plotted as volume fraction rather than mole fraction. 

Expression of the catalytic capacity of the immobilized laccase was also observed in more than a dozen different solvents, provided that they were either saturated with water or, in the case of solvents miscible with water, small amounts of water had been added (Table III). No enzymatic reaction was observed when the solvents tested were free of water. No correlation was found between the activity of the immobilized laccase and the hydrophobicity of the solvent in which the reaction took place. The rate of laccase reaction in ethylacetate was only twice that in toluene, despite the fact that water-saturated ethylacetate contains 50 times more water than... 

MW 290.19 CAS [107-49-3] an organophosphorus pesticide colorless liquid hygroscopic boiling point 124°C at 1 mm Hg vapor pressure 0.00047 torr at 20°C decomposes at 170 to 213°C density 1.185 g/ml at 20°C miscible with most organic solvents miscible with water but rapidly hydrolyzed highly toxic. 

Solvent manufacturer Honeywell Burdick Jackson [39] defines solvents as miscible if the two components can be mixed together in all proportions without forming two separate phases. A solvent miscibility chart (Figure 2.12) is a useful aid for determining which solvent pairs are immiscible and would therefore be potential candidates for use in LLE. More solvent combinations are miscible than immiscible, and more solvents are immiscible with water than with any other solvent. Solvents miscible with water in all proportions include acetone, acetonitrile, dimethyl acetamide, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, ethyl alcohol, glyme, isopropyl alcohol, methanol, 2-methoxyethanol, /V-methyI pyitoI idone. n-propyl alcohol, pyridine, tetrahydrofuran, and trifluoroacetic acid [40]. 

Examples from patents [S. Haber and N. Egger, US Patent 6 140 265 (2000), to Clariant S. Haber and H.-J. Kleiner, US Patent 5 756 804 (1998), to Hoechst-Clariant] describe the synthesis of 2-cyano-4 -methylbiphenyl by reaction of 2-chlorobenzonitrile and p-tolueneboronic acid, in the presence of Na2C03, PdCl2, and triphenylphosphinetrisulfonic acid (4 mol) in a water-toluene system, with a co-solvent miscible with water such as DMSO or... 

Incidental to this work is more evidence that the a-helix exists at the air-water interface. While some have appeared reluctant to accept this view, no good theoretical reason exists why it should not be stable. Where the nature of the side chain might provoke other conformations [as in poly(l-valine)] or the molecular weight is low or monolayers are spread from poor solvents miscible with water, other conformations are detectable, and the monolayer properties are significantly different (5). 

The mobile phases employed in reversed-phase chromatography usually consist of water to which an organic solvent - miscible with water (mostly methanol or acetonitrile) - is added. Generally an increased polarity of the mobile phase gives a decreased solvent strength, i.e. an increased k. For alkaloids - analyzed by means of water - methanol mixtures - systematical studies have been made . 

Properties White solid. Mp 99C, bp 185-200C (0.3 mm Hg). Slightly soluble in water and most organic solvents miscible with water at 80C. Combustible. 

Properties Liquid. Fp -50C, bp 240C, flash p 172F (11.1C), d 1.4250 (20/4C). Readily soluble in organic solvents miscible with water but readily hydrolyzed destroyed by bleaching powder, generating cyanogen chloride. Combustible. 

Properties Colorless, high-boiling liquid mild odor. Fp -56.4C, bp 216C, flash p 240F (115.5C), refr index 1.4055 (20C), bulk d 8.90 lb/gal (20C). Very stable at ordinary temperatures, compatible with many gums and resins, soluble in most organic solvents, miscible with water. When mixed with water is quite stable at room temperature, but at elevated temperatures it hydrolyzes slowly. Combustible. 

The colour stability of some thiocyanate systems is low (e.g., that with iron). This is connected with either the reducing properties of the thiocyanate or the slow polymerization of thiocyanic acid in acid solutions, which causes yellowing. Solvents miscible with water increase the colour intensity of thiocyanate complexes in aqueous solutions. This is apparently owing to the lowered dielectric constants of the media, which inhibit dissociation of the complexes. 

Reverse phase (RP) TLC with various solvents miscible with water (29 systems reported) has been examined for the separation of 17 triazine herbicides on DC-Alufolien Kieselgel 6OF254 (Merck) plates after overnight impregnation with 5% paraffin oil in n-hexane. Rf values for all systems studied were determined and recorded <84JC131>. 

I. 4250. IR absorption Acta Chem. Scand. 5, 1179 (]951). Readily sol in organic solvents. Miscible with water, but quickly hydrolyzed. Bleaching powder (chlorinated lime) destroys Tabun, but gives rise to cyanogen chloride. Extremely poisonousi LDm i.p. in mice 0.6 mg/kg, B. Holm -stedt, Pharmacol. Rev. 11, 567 (1959). The lethal dose for man may be as low as 0.01 mg/kg, Chem.. Eng. News 31, 4676 (1953). 

Additions of Solvents. Where a very insoluble and difficultly reducible nitro compound is to be reduced, the addition of a solvent miscible with water, such as ethyl alcohol, methanol, or pyridine, is often of considerable help. This makes for a smoother and more rapid reduction. In carr3dng out the reduction, the alkalinized iron oxide sludge is filtered off hot and washed with hot solvent. The resulting amine is then isolated from the filtrate. This method is used where reduction in water alone is extremely slow or where the final amine can be isolated only by solvent extraction. 

Alternative Components Cosolvent is used to dissolve the drug that is not totally soluble in the solvent in the dispersed phase. For example, organic solvents miscible with water, such as methanol and ethanol, are the common choices ... 

With the exception of formamide, the relative permittivities of organic solvents miscible with water are smaller than that of water. An increase in the concentration of the organic component of a solvent mixture therefore causes a decrease in the relative permittivity of the system in the case of the association of charged species, this favours their electrostatic interaction and hence an increase of the stability of the complex. 

Carotenoids are commonly extracted from liquid samples (plasma/serum) into lipophilic solvents such as hexane, hexane-ethyl acetate, or diethyl ether, mostly after deproteinization with ethanol or methanol, which also helps to liberate the lipidic substances from protein binding. Extracts should be protected from light and acids and antioxidants may usefully be added. The extract is either used as such or is concentrated under oxygen-free nitrogen. Solid samples, e.g., foods, are either extracted with a solvent miscible with water (acetone, methanol) or, after dehydration of the sample, with a water immiscible solvent. Cleanup of the extract and fractionation of the pigments may involve saponification and/or open-column chromatography. 

Solutions in organic solvents miscible with water 1,2,3... 

In nanoprecipitation, the polymer and the drug to be encapsulated are dissolved in an organic solvent miscible with water. This solution is then added dropwise to an aqueous solution of surfactants or stabilizers to form a stable suspension. Appropriate mixing, generally under turbulent conditions, and rapid diffusion of the solvent in the bulk phase create a suspension of polymer NPs that encapsulates the drug that is directly mixed in the organic phase. The most-used solvents are dimethylformamide and dimethyl sulfoxide, both of which are cytotoxic, so a procedure to remove the solvent is required after NP synthesis. This removal is usually obtained by dialysis. 

Hydrophilic Interaction LC-MS-Based Approaches Hydrophilic interaction LC (HILIC) is a variant of normal-phase LC. HILIC uses hydrophilic stationary phases, but employs reversed-phase type eluents. Any polar chromatographic surface can be used for HILIC separations, even nonpolar bonded silicas. A typical mobile phase for HILIC includes acetonitrile with a small amount of water. However, any aprotic solvent miscible with water (e.g., tetrahydrofunan or dioxane) can be used. Alcohols can also be used with a higher concentration. Ionic additives, such as ammonium acetate and ammonium formate, are usually used to serve as the modifiers for controlling the pH and ion strength of the mobile phase. 

In the wet method, a concentrated aqueous solution (ca. 25%) of sodium azide is stirred into a solution of the acid chloride in an orgmiic solvent miscible with water. The kind of sodium azide is immateri. The reaction mixture is usually kept at or below room temperature. The organic solvents that have been used m e acetone, > methanol, ethanol, dioxane, and acetic acid, of which acetone appears to be the most generally satisfactory. Acetic acid is not the best choice for either the wet or dry method, since it may react with the acid chloride to form the free acid and acetyl chloride, with consequent loss in yield and contmmnation of the product. The azide is precipitated completely by further dilution with water. Some azides have been prepared in the absence of any solvent except the water for the sodium azide this procedure is practicable only when both the... 

Most of them are organic compounds, and the practical problem that often arises is the precipitation in water of the basic or acidic form of the compound liberated during the titration. More simply, even the problem of the dissolution in water of the derivative to be titrated arises. In order to overcome this difficulty, an organic solvent miscible with water is often added. It may also be the case that the compound to titrate is soluble only in an organic solvent. In this case, if the adjuvant solvent is miscible in water, the solute is dissolved initially in the organic solvent in the titration vessel and then the purely aqueous solution of the titrant is added. 

Organic solvent (partially water miscible) Organic solvent (immiscible with water) Organic solvent (miscible with water)... 

The addition of solvents will significantly lower the surface tension. Suitable solvents in general are low-boiling solvents miscible with water. Some examples are methanol, ethanol, 2-propanol, and 1-butanol as well as volatile water miscible ketones like methyl ethyl ketone. An example for a formulation containing 2-propanol is given in Table 10.3. As a drawback the addition of solvent may decrease the dispersion stability of the PEDOTrPSS-dispersion. A special conductivity enhancing effect of low volatile polar solvents will be discussed in Section 10.4.5 "Conductivity-Enhancing Additives."... 

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