Water solubility constants

Water-soluble peroxide salts, such as ammonium or sodium persulfate, are the usual initiators. The initiating species is the sulfate radical anion generated from either the thermal or redox cleavage of the persulfate anion. The thermal dissociation of the persulfate anion, which is a first-order process at constant temperature (106), can be greatly accelerated by the addition of certain reducing agents or small amounts of polyvalent metal salts, or both (87). By using redox initiator systems, rapid polymerizations are possible at much lower temperatures (25—60°C) than are practical with a thermally initiated system (75—90°C). 

Osmotic Control. Several oral osmotic systems (OROS) have been developed by the Alza Corporation to allow controUed deHvery of highly water-soluble dmgs. The elementary osmotic pump (94) consists of an osmotic core containing dmg surrounded by a semi-permeable membrane having a laser-drilled deHvery orifice. The system looks like a conventional tablet, yet the outer layer allows only the diffusion of water into the core of the unit. The rate of water diffusion into the system is controUed by the membrane s permeabUity to water and by the osmotic activity of the core. Because the membrane does not expand as water is absorbed, the dmg solution must leave the interior of the tablet through the smaU orifice at the same rate that water enters by osmosis. The osmotic driving force is constant until aU of the dmg is dissolved thus, the osmotic system maintains a constant deHvery rate of dmg until the time of complete dissolution of the dmg. 

Since the free water remains constant (except when there is evaporation), the final amount of soluble MgS04-7H20 is calculated by the ratio of 0,538 lb MgS04-7H20 (1 — 0,538) lb free water... 

Water-soluble polymers and polyelectrolytes (e.g., polyethylene glycol, polyethylene imine polyacrylic acid) have been used success-hilly in protein precipitations, and there has been some success in affinity precipitations wherein appropriate ligands attached to polymers can couple with the target proteins to enhance their aggregation. Protein precipitation can also be achieved using pH adjustment, since proteins generally exhibit their lowest solubility at their isoelectric point. Temperature variations at constant salt concentration allow for frac tional precipitation of proteins. 

They are usually administered intramuscularly by Injection. Since they are not soluble in water they form a so-called depot that remains at or near the site of injection. As the esters slowly hydrolyze by exposure to body fluids, the relatively water-soluble estrone is released and finds its way into the bloodstream. In this way the patient is provided with a reasonably constant low-level dose of the hormone. 

Solvent B.P. cc) Dielectric constant Water solubility (g/lOOg)... 

Figure 5a indicates the effect of the CTAB concentration on the rate constants of the complexes of 38b and 38c. In the case of the water soluble 38b ligand, the rate increases with increasing CTAB concentration up to a saturation level. This type of saturation kinetics is usually interpreted to show the incorporation of a ligand-metal ion complex into a micellar phase from a bulk aqueous phase, and the catalytic activity of the complex is higher in the micellar phase than in the aqueous phase. In the case of lipophilic 38c, a very similar curve as in Fig. 4 is obtained. At a first glance, there appears to be a big difference between these two curves. However, they are rather common in micellar reactions and obey the same reaction mechanism 27). 

Swann R, Laskowski D, McCAll P, et al. 1983. A rapid method for the estimation of the environmental parameters octanol/water partition coefficient, soil sorption constant, water to air ratio, and water solubility. Residue Rev 85 18-28. 

Under aqueous conditions, flavonoids and their glycosides will also reduce oxidants other than peroxyl radicals and may have a role in protecting membranal systems against pro-oxidants such as metal ions and activated oxygen species in the aqueous phase. Rate constants for reduction of superoxide anion show flavonoids to be more efficient than the water-soluble vitamin E analogue trolox (Jovanovic et al, 1994), see Table 16.1. 

Orange shades are realized with lipophilic natural colorants like paprika oleo-resin, P-carotene, and canthaxanthin after previous emulsification to yield water-dispersible forms. Yellow shades can be achieved using turmeric as a water-soluble solution, but the solution is light sensitive. To maintain constant color, 3 to 6 ppm of P-carotene may be added. Stable brown coloration is obtained from caramel a concentrated syrup is easily incorporated, well flavored and stable in creams. ... 

Water solubility, dissociation constant(s) and n-octanol/water partition coefficients allow one to predict how an analyte may behave on normal-phase (NP), reversed-phase (RP), or ion-exchange solid-phase extraction (SPE) for sample enrichment and cleanup. 

Acid dissociation constant Regression correlation coefficient Regression coefficient of determination Water solubility... 

It is desirable to determine the chemical properties of irrigation water, paddy water in the field, and adjacent streams and rivers. Since especially the pH of the paddy water fluctuates diurnally (high in daytime and low at night), this may affect the water solubility of certain chemicals, e.g., sulfonylureas, which have dissociation constants (p/fa) in an environmentally relevant range. 

As examples of some water-soluble salts, mention may be made of potassium chloride, copper sulfate, and sodium vanadate. As examples of some water-insoluble salts, mention may be made of some typical ones such as lead chloride, silver chloride, lead sulfate, and calcium sulfate. The solubilities of most salts increases with increasing temperature. Some salts possess solubilities that vary very little with temperature or even decline. An interesting example is provided by ferrous sulfate, the water solubility of which increases as temperature is raised from room temperature, remains fairly constant between 57 and 67 °C, and decreases at higher temperatures to below 12 g l-1 at 120 °C. Table 5.2 presents the different types of dissolution reactions in aqueous solutions, and Table 5.3 in an indicative way presents the wide and varied types of raw materials that different leaching systems treat. It will be relevant to have a look at Table 5.4 which captures some of the essential and desirable features for a successful leaching system. 

The purified tetraethyl pyrophosphate is a colorless, odorless, water-soluble, hygroscopic liquid (24, 4 )- It possesses a very high acute toxicity (28), exceeding that of parathion, and is rapidly absorbed through the skin. There is no spray-residue problem, however, for tetraethyl pyrophosphate hydrolyzes even in the absence of alkali to nontoxic diethyl phosphoric acid. Hall and Jacobson (24) and Toy (47) have measured its rate of hydrolysis, which is a first-order reaction. Its half-life at 25° C. is 6.8 hours and at 38° C. is 3.3 hours. Coates (10) determined the over-all velocity constant at 25° C. k = 160 [OH-] + 1.6 X 10 3 min.-1 Toy (47) has described an elegant method for preparing this ester as well as other tetraalkyl pyrophosphates, based upon the controlled hydrolysis of 2 moles of dialkyl chlorophosphate ... 

Physical data important for describing environmental behavior (Koc, Kow, vapor pressure, water solubility, and Henry s law constant) are incomplete. In general, hydraulic fluids have relatively low water solubilities. 

The log Kow, water solubilities, and Henry s law constants of several of the components that are present in the organophosphate ester hydraulic fluids included in this profile have been measured and are presented in Tables 3-4, 3-5, 3-8, and 3-9. In general, chemicals with low Kow (log Knw <1) tend to have high water solubilities, do not sorb to sediments, and do not bioconcentrate chemicals with high Kow tend to have low water solubilities, partition to sediments and soil, and bioconcentrate in fish (Lyman et al. 1982). Most of the values presented above are for mixtures and are the average values for all of the components in the mixture. 

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