Solubilization polar compounds

Table 2.5), and the hydrogen bonds of water also assist in solubilizing polar compounds. 

The nonpolar character of hexane and the alkanes severely limits their ability to solubilize polar compounds. Since the NP support material typically has a polar surface (such as silica), some polar mobile phase component is needed to elute the solute. Therefore, a low level (typically <5C5% v/v) of a more polar component, such as dichloromethane or ethyl acetate, often needs to be included as part of the mobile... 

As its name suggests, supercritical fluid extraction (SEE) relies on the solubilizing properties of supercritical fluids. The lower viscosities and higher diffusion rates of supercritical fluids, when compared with those of liquids, make them ideal for the extraction of diffusion-controlled matrices, such as plant tissues. Advantages of the method are lower solvent consumption, controllable selectivity, and less thermal or chemical degradation than methods such as Soxhlet extraction. Numerous applications in the extraction of natural products have been reported, with supercritical carbon dioxide being the most widely used extraction solvent. However, to allow for the extraction of polar compounds such as flavonoids, polar solvents (like methanol) have to be added as modifiers. There is consequently a substantial reduction in selectivity. This explains why there are relatively few applications to polyphenols in the literature. Even with pressures of up to 689 bar and 20% modifier (usually methanol) in the extraction fluid, yields of polyphenolic compounds remain low, as shown for marigold Calendula officinalis, Asteraceae) and chamomile Matricaria recutita, Asteraceae). " ... 

RFG RME Rust inhibitor Reformulated gasoline. Repassed methyl ester. Lubricant additive minimizes rust by preferential adsorption of polar compounds on metal surface to provide a protective film and/or neutralization of corrosive acids, e.g., fatty acids, nitrogen compounds, carbonate-alkylbenzenosulfonate.RMs. Water is solubilized by soft-core Rms. 

In aqueous solutions the micellar assembly structure allows sparingly soluble or water-insoluble chemical species to be solubilized, because they can associate and bind to the micelles. The interaction between surfactant and analyte can be electrostatic, hydrophobic, or a combination of both [76]. The solubilization site varies with the nature of the solubilized species and surfactant [77]. Micelles of nonionic surfactants demonstrate the greatest ability for solubilization of a wide group of various compounds for example, it is possible to solubilize hydrocarbons or metal complexes in aqueous solutions or polar compounds in nonpolar organic solutions. As the temperature of an aqueous nonionic surfactant solution is increased, the solution turns cloudy and phase separation occurs to give a surfactant-rich phase (SRP) of small volume containing the analyte trapped in micelle structures and a bulk diluted aqueous phase. The temperature at which phase separation occurs is known as the cloud point. Both CMC and cloud point depend on the structure of the surfactant and the presence of additives. Table 6.10 gives the values of CMC and cloud point for the surfactants most frequently applied in the CPE process. 

These BCF values of these very lipophilic polycyclic musk fragrances are relatively low compared to the predicted BCF values calculated by means of Eq. (26). At this time no exact explanation for this phenomenon can be given. It is known that the parent chemicals HHCB and AHTN are metabolized in the fish to more polar compounds that will be eliminated at a higher rate. It is also possible that the low BCF value of C-AHTN may be due to the low radiochemical purity of 78.8%. It seems therefore necessary to perform bioconcentration tests with PMFs of high purity in the absence of a solubilizer and to use water concentrations of these very lipophilic PMFs in the lower ng range, which are found in fresh water systems [362], and to use the kinetic approach. At this time no exact water solubility data are available. 

Eq. (4) predicts that an exponential increase in solubility of a non-polar compound occurs as the volume fraction of cosolvent is increased. However, dilution of a cosolvent-solubilized preparation with an aqueous medium, such as blood or intravenous (IV) infusion... 

Water is a good solvent for most biomolecules, which are generally charged or polar compounds. Solubilization of compounds with functional groups such as ionized carboxylic acids (COOQ, protonated amines (NH3+), phosphate esters, or anhydrides is also a result of hydration and charge screening. 

Outstanding solubilizing power for polar compounds (hydration)... 

Cosolvents can enhance solubility of compounds in CO2, a topic beyond the scope of this chapter. It is useful, however, to point out some details on cosolvents in CO2. McHugh et al. demonstrate that a cosolvent can provide the specific interactions that are necessary to solubilize a compound in CO2 (70,71). For instance, butyl acrylate (BA) and ethyl hexyl acrylate (EHA) decrease the cloud point pressure of acrylate polymers owing to the specific polar interactions between the cosolvent with the acrylate backbone of the polymer (70). Addition of ethyl methacrylate (EMA) and butyl methacrylate (BMA) reduces the pressure needed to solubilize poly(ethyl methacrylate) (PEMA) and poly(butyl methacrylate) (PBMA) in CO2 (71). 

Jafvert C.T., Van Hoof P.L. and Heath J.K., Solubilization of non-polar compounds by non-ionic surfactant micelles . Water Research. 28, 1009-1017. (1994)... 

If small amounts of hydrocarbons or long-chain polar compounds are added to an aqueous solution of a surfactant above its CMC, these normally water-insoluble materials may be solubilized in the micelles (Chapter 4). This solubilization generally causes an increase in the aggregation number of the micelle, and as the amount of material solubilized by the micelle increases, the aggregation continues to increase until the solubilization limit is reached. 

Just as polar compounds that are believed to penetrate into the inner portion of the core produce only small depressions of the CMC, so, too, hydrocarbons, which are solubilized in the inner portion of the core, decrease the CMC only slightly. Very short-chain polar compounds, (e.g., dioxane and ethanol) at low bulk phase concentrations also depress the CMC, but the effect here, too, is small (Shirahama, 1965). In these compounds, adsorption probably occurs on the surface of the micelle, close to the hydrophilic head. 

Effect of Monomeric Organic Additives The presence of solubilized hydrocarbon in the surfactant micelles generally increases the solubility of polar compounds in these micelles. The solubilized hydrocarbon causes the micelle to swell, and this may make it possible for the micelle to incorporate more polar material in the palisade layer. On the other hand, the solubilization of such... 

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