Solubility enhanced rate

Research on catalytic coal Hquefaction was also carried out using an emulsified molybdenum catalyst added to the slurry medium to enhance rates of coal conversion to distiUate (26). Reaction at 460°C, 13.7 MPa (1980 psi) in the presence of the dispersed catalyst was sufficient to greatiy enhance conversion of a Pittsburgh No. 8 biturninous coal to hexane-soluble oils ... 

Various initiation strategies and surfactant/cosurfactant systems have been used. Early work involved in situ alkoxyamine formation with either oil soluble (BPO) or water soluble initiators (persulfate) and traditional surfactant and hydrophobic cosurfactants. Later work established that preformed polymer could perform the role of the cosurfactant and surfactant-free systems with persulfate initiation were also developed, l90 222,2i3 Oil soluble (PS capped with TEMPO,221 111,224 PBA capped with 89) and water soluble alkoxyamines (110, sodium salt""4) have also been used as initiators. Addition of ascorbic acid, which reduces the nitroxide which exits the particles to the corresponding hydroxylamine, gave enhanced rates and improved conversions in miniemulsion polymerization with TEMPO.225 Ascorbic acid is localized in the aqueous phase by solubility. 

Paracrystallinity, Cu/ZnO/AIjOj, 31 295 2"-Paracyclophanes, 32 453 Paracyclophanes, macrocycles, 29 206-208 Paraffin, see also Alkanes alkylation, 10 165, 27 98 carbon selectivity, bed residence time effects, 39 249-250 cracking, 39 283 cyclization, 28 295 rates, 28 301, 302 double cyclization, 28 312-314 in exhaust gases, 24 66, 67 hydrogenolysis, 30 43-44 hydroisomerization, 39 183 oxidation, 32 118-121 solubility enhanced hydrogeolysis, 39 285 Parahydrogen conversion rate correlations, 27 48-50... 

The selectivity of the ozone reaction in pure solvent or water-solvent systems is known from early studies conducted by chemists under analytical and preparative aspects (Bailey, 1958). Inert solvents (e. g. pentane, carbon tetrachloride) provide an opportunity to produce and study oxidation products of the ozonolysis, such as ozonides at low temperatures (Criegee, 1975). Only in the last two decades have ozonation techniques been developed and studied that utilize the higher ozone solubility, enhanced mass transfer rates, higher reaction rates etc. to be found in water-solvent systems. 

Joshi, V. Y., and M R. Sawant. 2006. Study on dissolution rate enhancement of poorly water soluble drug Contributions of solubility enhancement and relatively low micelle diffusivltpispers. Sci. Technol. 27 1141-1150. 

The majority of characterized solvates are stoichiometric, with either water or organic solvents present in a Lxed ratio with the drug molecules. Glibenclamide was isolated as two nonsolvated polymorphs, a pentanol solvate, and a toluene solvate (Suleiman and Najib, 1989). Furosemide could form solvates with dimethylformamide or dioxane (Matsuda and Tatsumi, 1989). Haleblian and McCrone (1969) studied the solid forms of steroids, and found different dissolution rates for two monohydrates of Luprednisolone, a monoethanol and hemiacetone solvate of prednisolone and two monoethanolates and a hemichloroform solvate of hydrocortisone. Other solvents that have been reported to form solvates with drugs include methyl ethyl ketone, propanol, hexane, dimethylsulfoxide, acetonitrile, and pyridine. The potential toxicity concerns eliminate most of these from consideration as practical mechanisms of solubility enhancement for human therapeutics. 

Another important factor that may inLuence solubility, dissolution rate, and therefore absorption of water-insoluble compounds is the contents ofthe Gl Luids. The Gl Luids contain various materials, such as bile salts, enzymes, and mucin. Bile salts are surface active and as such could potentially enhance the rate or extent of absorption of water-insoluble drugs. Thus, the increased absorption of a water-insoluble compound, griseofulvin (GF), after a fatty meal may be facilitated by bile salt secretion into the gut resulting in solubilization [1,2],... 

In this study, the effects of cosolvent (EtOH) addition on the solubilization and recovery of PCE by a nonionic surfactant (Tween 80) was evaluated using a combination of batch, column and 2-D box studies. Batch results demonstrated that the addition of 5% and 10% EtOH increased the solubilization capacity of Tween 80 from 0.69 g PCE/g surfactant to 1.09 g PCE/g surfactant. For a 4% Tween 80 solution, this translates into a solubility enhancement of more than 50%, from 26,900 mg/L to 42,300. mg/L. When the surfactant formulations were flushed through soil columns containing residual PCE, effluent concentration data clearly showed that PCE solubilization was rate-limited, regardless of the EtOH concentration. Using analytical solutions to the 1-D ADR equation, effective mass transfer coefficients (Ke) were obtained from the effluent concentration data for both steady-state (A e ) and no flow conditions The addition of EtOH had... 

Dihydroxylation of alkenes. C6H5B(OH)2 is useful for capture of the diols formed on osmylation with 0s04 and N-methylmorpholine N-oxide, particularly unstable or water-soluble diols. Osmylation with the borane can also be conducted in a nonaqueous medium with enhanced rates.1... 

In homogeneous catalysis ligand systems may define the medium for the reaction. Water-soluble ligands have been developed, but in other instances two phases have to be used. Ultrafiltration may become a useful technique for catalyst removal if one uses encapsulated homogeneous catalysts or larger oligomeric catalysts. New catalytic systems involve the use of easily functionalizable den-drimers. In all these systems a combination of catalysis and separation can be envisaged that also enhances rates and selectivity. 

Additional data are needed to better define the exposure of humans and, in the context of animal toxicity studies, of laboratory animals. Because JP-8 is a complex mixture of chemicals that differ in volatility, solubility, metabolic rate and pathway, and rate and route of elimination from the body, dosimetry of critical components of the mixture at critical sites in the body is important to enhance the quality of risk assessment. The fact that human exposures can involve liquid fuel, aerosolized fuel, and vapor, by inhalation, dermal, and oral routes of exposure makes it difficult to accurately predict the internal dose of JP-8 and its components. 

Reaction mixtures are complex multicomponent systems, and their phase behavior is dictated by the composition of the mixture and operating conditions. Organic solvents present in the reaction medium as reagents may act as cosolvents and result in solute solubility enhancement (as discussed in Section 4.2). For example, the decrease in reaction rate observed at high ethanol concentrations for the lipase-catalyzed esterification of myristic acid + ethanol in SCCO2 has been, in part, attributed to the solubility enhancement of water, resulting in drying of the enzyme... 

Solubility enhancement by use of cyclodextrins is achieved for a number of drug substances, an approach of interest in formulation of drugs for topical, parenteral, and oral use (Stella and Rajewski, 1997 Loftsson and Masson, 2001 Qi and Sikorski, 2001). The solubilizing effect can be extensive even in low concentrations of cyclodextrin. The use of 0.1 M sulfobutyl-ether-P-cyclodextrin increases the solubility of prednisolone acetate and testosterone by a factor of 426 and 2020, respectively (Myrdal and Yalkowsky, 2002). Cyclodextrin encapsulation of a molecule will affect many of its physicochemical properties (Loftsson, 1995). As a result of complexation, solubility, pKa value, spectral properties, and the chemical reactivity of the included substance will change. The cyclodextrins are known to affect molecular orientation and to have an influence on rates and efficiency of electron transfer, excited state proton transfer, and rate of decomposition (Chattopadhyay, 1991 Fox, 1991 Sur et al., 2000). Cyclodextrins can also be used in combination with liposomes a cyclodextrin-liposome entity represents an even more complex environment to the drug molecule (Loukas et al., 1995). 

G-agents are readily decontaminated by basic hydrolysis in aqueous solution or in aqueous alcohol to improve solubility. At high pH, hydrolysis is virtually instantaneous. As discussed above, significantly enhanced rates of hydrolysis are observed in the presence of hypochlorite or peroxide ions. 

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