Solubilization solubilizer

Immiscible solvents like water and oil can be transformed by addition of solubilizers to single-phase solutions. Amphiphilic substances are known as effective solubilizers. Solubilization depends on the HLB of the components that ought to form a single phase and on the kind of solubilizer used. Phosphorus-containing surfactants with their variety of possible molecular structures are solubilizers that can be tailored to the task demanded. 

In order to avoid misleading spots on the 2-DE profile and to remove salts, lipids, polysaccharides, or nucleic acids interfering with separation, samples should be solubilized. Solubilization procedure involves disruption of all noncovalently bond protein complexes into a solution of polypeptides. It is the most critical step of 2-DE. 

Chemical solubilization Solubilization of cell walls by surfactants, alkali, or... 

Dehydrated ethanol Solubilizer, solubilizing agent, solvent iv, im, sc... 

Cosolvents can be a powerful tool by which to solubilize drugs. For a given cosolvent selected, it is clear that the degree of solubilization attained for any solute is directly proportional to the octanol/water partition coefficient of that solute. However, as with pH solubilization, solubilization through cosolvents is logarithmic, and as a result there is the potential for precipitation upon dilution. 

One of the important properties of surfactants that is directly related to micelle formation is solubilization. Solubilization may be defined as the spontaneous dissolving of a substance (solid, liquid, or gas) by reversible interaction with the micelles of a surfactant in a solvent to form a thermodynamically stable isotropic solution with reduced thermodynamic activity of the solubilized material. Although both solvent-soluble and solvent-insoluble materials may be dissolved by the solubilization mechanism, the importance of the phenomenon from the practical point of view is that it makes possible the dissolving of substances in solvents in which they are normally insoluble. For example, although ethylbenzene is normally insoluble in water, almost 5 g of it may be dissolved in 100 mL of a 0.3 M aqueous solution of potassium hexadecanoate to yield a clear solution. 

Solubilization Solubilization has long been known to be a major factor in the removal of oily soil and its retention by the bath. This is based upon the observation (Ginn, 1961 Mankowich, 1961) that oily soil removal from both hard and textile surfaces becomes significant only above the CMC for nonionics and even for some anionics having low CMCs, and reaches its maximum only at several times the CMC. A considerable amount of research has been devoted to the removal of... 

In an earlier review [3], mixed micelles formed by bile salts were classified into those with (i) non-polar lipids (e.g., linear or cyclic hydrocarbons) (ii) insoluble amphiphiles (e.g., cholesterol, protonated fatty acids, etc.) (iii) insoluble swelling amphiphiles (e.g., phospholipids, monoglycerides, acid soaps ) and (iv) soluble amphiphiles (e.g., mixtures of bile salts with themselves, with soaps and with detergents) and the literature up to that date (1970) was critically summarized. Much recent work has appeared in all of these areas, but the most significant is the dramatic advances that have taken place in our understanding of the structure, size, shape, equilibria, and thermodynamics of bile salt-lecithin [16,18,28,29,99-102,127, 144,218,223,231-238] and bile salt-lecithin-cholesterol [238,239] micelles which are of crucial importance to the solubihty of cholesterol in bile [1]. This section briefly surveys recent results on the above subclasses. Information on solubilization, solubilization capacities or phase equilibria of binary, ternary or quaternary systems or structures of liquid crystalline phases can be found in several excellent reviews [5,85,207,208,210,211,213,216,217] and, where relevant, have been referred to earlier. 

Solubilization. Solubilization is caused by surfactants added in concentrations above the cmc (critical micelle concentration) level, which are for conunon surfactants in the range M. When added in concentrations not far exceeding the cmc... 

The PLA2 activity in microsomal preparations from developing elm seed embryos was solubilized with the non-ionic detergent Lubrol PX at 0.3% (w/v) in 0.15 M potassium phosphate buffer, pH 7.2. About 85% of the microsomal PLA2 activity and 80-90% of the microsomal proteins were solubilized. Solubilization was verified by high speed centrifugation (the activity was not pelleted by 100 000 x g for 60 min) and by gel filtration on a Superose 6 column, where all activity was recovered in the included volume. 

Autoclave/Sonlcatlon Method for Solubilization. Solubilization of maize starches by autoclaving followed by sonlcatlon In both an aqueous and an alkali system was performed according to the method of Jackson et al. (2). 

Solubilization by micelles has been described in detail in Chapter 13, and only a summary is given here. As discussed in Chapter 13, solubilisation is the incorporation of an insoluble substance (usually referred to as the substrate) into surfactant micelles (the solubilizer). Solubilization may also be referred to as the formation of... 

Simplest examples are prepared by the cyclic oligomerization of ethylene oxide. They act as complexing agents which solubilize alkali metal ions in non-polar solvents, complex alkaline earth cations, transition metal cations and ammonium cations, e.g. 12—crown —4 is specific for the lithium cation. Used in phase-transfer chemistry. ... 

Can be coupled in the 4-position with dia-zotized bases to give a series of azo dyestuffs more usually it is first sulphonated to give a valuable series of intermediates for solubilized azo dyestuffs. The nitro-l-naphthols are themselves dyestuffs, e.g. 2,4-dinitro-l-naph-thol ( naphtol yellow ). 

Sulphonation is widely used for the solubilization of insoluble azo dyestuffs. 

Surfactants have also been of interest for their ability to support reactions in normally inhospitable environments. Reactions such as hydrolysis, aminolysis, solvolysis, and, in inorganic chemistry, of aquation of complex ions, may be retarded, accelerated, or differently sensitive to catalysts relative to the behavior in ordinary solutions (see Refs. 205 and 206 for reviews). The acid-base chemistry in micellar solutions has been investigated by Drummond and co-workers [207]. A useful model has been the pseudophase model [206-209] in which reactants are either in solution or solubilized in micelles and partition between the two as though two distinct phases were involved. In inverse micelles in nonpolar media, water is concentrated in the micellar core and reactions in the micelle may be greatly accelerated [206, 210]. The confining environment of a solubilized reactant may lead to stereochemical consequences as in photodimerization reactions in micelles [211] or vesicles [212] or in the generation of radical pairs [213]. 

Finally, micellar systems are useful in separation methods. Micelles may bind heavy-metal ions, or, through solubilization, organic impurities. Ultrafiltration, chromatography, or solvent extraction may then be used to separate out such contaminants [220-222]. 

The cleaning process proceeds by one of three primary mechanisms solubilization, emulsification, and roll-up [229]. In solubilization the oily phase partitions into surfactant micelles that desorb from the solid surface and diffuse into the bulk. As mentioned above, there is a body of theoretical work on solubilization [146, 147] and numerous experimental studies by a variety of spectroscopic techniques [143-145,230]. Emulsification involves the formation and removal of an emulsion at the oil-water interface the removal step may involve hydrodynamic as well as surface chemical forces. Emulsion formation is covered in Chapter XIV. In roll-up the surfactant reduces the contact angle of the liquid soil or the surface free energy of a solid particle aiding its detachment and subsequent removal by hydrodynamic forces. Adam and Stevenson s beautiful photographs illustrate roll-up of lanoline on wood fibers [231]. In order to achieve roll-up, one requires the surface free energies for soil detachment illustrated in Fig. XIII-14 to obey... 

In addition to lowering the interfacial tension between a soil and water, a surfactant can play an equally important role by partitioning into the oily phase carrying water with it [232]. This reverse solubilization process aids hydrody-namically controlled removal mechanisms. The partitioning of surface-active agents between oil and water has been the subject of fundamental studies by Grieser and co-workers [197, 233]. 

K. Shinoda and S. Friberg, Emulsions and Solubilization, Wiley, New York, 1986. 

Yamakoshi Y N, Yagami T, Fukuhara K, Sueyoshi S and Miyata N 1994 Solubilization of fullerenes into water with polyvinylpyrrolidone applioable to biologioal tests J. Chem. Soc., Chem. Common. 517-18... 

Guldi D M, Huie R E, Neta P, Hungerbuhler H and Asmus K-D 1994 Excitation of Cgg, solubilized in water by... 

Micelles are mainly important because they solubilize immiscible solvents in their cores. Nonnal micelles solubilize relatively large quantities of oil or hydrocarbon and reverse micelles solubilize large quantities of water. This is because the headgroups are water loving and the tailgroups are oil loving. These simple solubilization trends produce microemulsions (see section C2.3.11). 

Other solubilization and partitioning phenomena are important, both within the context of microemulsions and in the absence of added immiscible solvent. In regular micellar solutions, micelles promote the solubility of many compounds otherwise insoluble in water. The amount of chemical component solubilized in a micellar solution will, typically, be much smaller than can be accommodated in microemulsion fonnation, such as when only a few molecules per micelle are solubilized. Such limited solubilization is nevertheless quite useful. The incoriDoration of minor quantities of pyrene and related optical probes into micelles are a key to the use of fluorescence depolarization in quantifying micellar aggregation numbers and micellar microviscosities [48]. Micellar solubilization makes it possible to measure acid-base or electrochemical properties of compounds otherwise insoluble in aqueous solution. Micellar solubilization facilitates micellar catalysis (see section C2.3.10) and emulsion polymerization (see section C2.3.12). On the other hand, there are untoward effects of micellar solubilization in practical applications of surfactants. Wlren one has a multiphase... 

Micelles can solubilize gases. It has been demonstrated [49] that the Laplace model gives a good description of such solubilization for the case of ionic micelles ... 

The solubilization of diverse solutes in micelles is most often examined in tenns of partitioning equilibria, where an equilibrium constant K defines the ratio of the mole fraction of solute in the micelle (X and the mole fraction of solute in the aqueous pseudophase. This ratio serves to define the free energy of solubilization -RT In K). 

It is of particular interest to be able to correlate solubility and partitioning with the molecular stmcture of the surfactant and solute. Likes dissolve like is a well-wom plirase that appears applicable, as we see in microemulsion fonnation where reverse micelles solubilize water and nonnal micelles solubilize hydrocarbons. Surfactant interactions, geometrical factors and solute loading produce limitations, however. There appear to be no universal models for solubilization that are readily available and that rest on molecular stmcture. Correlations of homologous solutes in various micellar solutions have been reviewed by Nagarajan [52]. Some examples of solubilization, such as for polycyclic aromatics in dodecyl sulphonate micelles, are driven by hydrophobic... 

A particularly interesting type of micellar catalysis is the autocatalytic self-replication of micelles [58]. Various examples have been described, but a particularly interesting case is the biphasic self-reproduction of aqueous caprylate micelles [59]. In this system ethyl caprylate undergoes hydroxyl catalysed hydrolysis to produce the free carboxylate anion, caprylate. Caprylate micelles then fonn. As these micelles fonn, they solubilize ethylcaprylate and catalyse further production of caprylate anion and caprylate micelles. 

King A D 1995 Solubilization of gases Solubilization in Surfactant Aggregates ed S D Christian and J F Scamehorn (New York Dekker) pp 35-58... 

Christian S D and Scamehorn J F (eds) 1995 Solubilization in Surfactant Aggregates (New York Dekker)... 

Sharma R (ed) 1995 Surfactant Adsorption and Surface Solubilization (Washington, DC American Chemical Society)... 

Nagara]an R 1996 Solubilization in aqueous solutions of amphiphiles Curr. Opin. Colloid Interface Sc/. 1 391-401... 

Calculations usirig this value afford a partition coefficient for 5.2 of 96 and a micellar second-order rate constant of 0.21 M" s" . This partition coefficient is higher than the corresponding values for SDS micelles and CTAB micelles given in Table 5.2. This trend is in agreement with literature data, that indicate that Cu(DS)2 micelles are able to solubilize 1.5 times as much benzene as SDS micelles . Most likely this enhanced solubilisation is a result of the higher counterion binding of Cu(DS)2... 

In the first method a secondary acetylenic bromide is warmed in THF with an equivalent amount of copper(I) cyanide. We found that a small amount of anhydrous lithium bromide is necessary to effect solubilization of the copper cyanide. Primary acetylenic bromides, RCECCH Br, under these conditions afford mainly the acetylenic nitriles, RCsCCHjCsN (see Chapter VIII). The aqueous procedure for the allenic nitriles is more attractive, in our opinion, because only a catalytic amount of copper cyanide is required the reaction of the acetylenic bromide with the KClV.CuCN complex is faster than the reaction with KCN. Excellent yields of allenic nitriles can be obtained if the potassium cyanide is added at a moderate rate during the reaction. Excess of KCN has to be avoided, as it causes resinifi-cation of the allenic nitrile. In the case of propargyl bromide 1,1-substitution may also occur, but the propargyl cyanide immediately isomerizes under the influence of the potassium cyanide. 

The protecting groups are also used to solubilize synthetic intermediates in organic solvents, e.g. methylene chloride. Chromatography is then possible on a larger scale, since silica gel can be used as adsorbent. Six synthetic strategies have been developed (H. Kdster, 1979) ... 

Esters can participate m hydrogen bonds with substances that contain hydroxyl groups (water alcohols carboxylic acids) This confers some measure of water solubil ity on low molecular weight esters methyl acetate for example dissolves m water to the extent of 33 g/100 mL Water solubility decreases as the carbon content of the ester increases Fats and oils the glycerol esters of long chain carboxylic acids are practically insoluble m water... 

The surfactant is initially distributed through three different locations dissolved as individual molecules or ions in the aqueous phase, at the surface of the monomer drops, and as micelles. The latter category holds most of the surfactant. Likewise, the monomer is located in three places. Some monomer is present as individual molecules dissolved in the water. Some monomer diffuses into the oily interior of the micelle, where its concentration is much greater than in the aqueous phase. This process is called solubilization. The third site of monomer is in the dispersed droplets themselves. Most of the monomer is located in the latter, since these drops are much larger, although far less abundant, than the micelles. Figure 6.10 is a schematic illustration of this state of affairs during emulsion polymerization. 

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