Diphasic systems

Biocatalyst preparation Immobilization method Catalyzed reaction Diphasic system Characteristics Reference... 

Molecular and Dissociated States of Molecules Diphasic Systems... 

Table 5 Overall mass transport coefficients kn and kna values for the mass transport of prenal and citral in the Diphasic system n-hexane/water...

Product isolation and recovery of the catalyst is relatively easy in aqueous/organic diphasic systems and in several cases the aqueous solution of the catalyst was reused with only negligible loss of the reaction rate or of theenantioselectivity [105,112],... 

Figure 5.2 The domain of application of in vitro techniques used to measure partition coefficients in 1-octanol/water system and in other diphasic systems. In gray medium- or low-throughput methods not described in this chapter.

Thus, dimer 276 is obtained from salt 30 at room temperature in a diphase system of 10% aqueous solution of sodium hydroxide and ether. On heating with alkali in isopropyl alcohol, these dimers are converted quantitatively into benz[a]anthracenes 278 (88KGS1185), and likewise the formation of dihydro-derivatives of chrysenes 271 (85KGS910) and 277... 

Shimizu, S., Kataoka, M., Katoh, M., Morikawa, T., Miyoshi, T., and Yamada, H. 1990a. Stereoselective reduction of ethyl 4-chloro-3-oxobutanoate by a microbial aldehyde reductase in an organic solvent-water diphasic system. Appl. Environ. Microbiol, 56, 2374-2377. 

With tantalum effusion cells, the results of Ackermann et al. (16) are virtually identical with the earlier work of Phipps et al. (19) (1593-2063 K) and yielded total vapor pressure values of plutonium-bearing species which were considerably higher (by approximately a factor of ten) than those obtained with the less reducing tungsten (as well as Re and Ir) cells. Ackermann et al. (16) correlated the vapor pressure results obtained with tantalum effusion cells with the univariant diphasic system consisting of Pu203(s)-PuOi,51(s) as the condensed phases and PuO(g) as the primary gaseous species. 

Rhodium-catalyzed [2+2+2] cyclotrimerization of alkynes in an aqueous-organic diphasic system was also employed in die formation of dihydrobenzo[c]furans as depict in the scheme below. Medium- and large-sized rings could be obtained by utilizing this approach <03JA7784>. 

Product separation is easier for diphasic systems, especially (but not only) those incorporating the aqueous biphasic and water-soluble catalysts. Figure 4 (below)... 

Unfortunately, the study of phase equilibria in solution, e.g., liquid-solid adsorption, is not a highly popular area of research. Gas-solid adsorption and vapor-solution equilibria have been studied in far more detail, although most of the information available concerns the fate of single components in a diphasic system. Liquid-solid adsorption has benefited mainly from the extension of the concepts developed for gas phase properties to the case of dilute solutions. Multicomponent systems and the competition for interaction with the stationary phase are research areas that have barely been scratched. The problems are difficult. The development of preparative chromatography and its applications are changing this situation. 

Duxin N ef a/1997 Nanosized Fe-Cu-B alloys and composites synthesized in diphasic systems J. Phys. Chem. B 101 8907... 

Diphasic systems were found to have a unique effect on the selectivity of the addition of arylboronic acids to alkynes. It was found that the use of [Rh(COD)OH]2 associated with the water-soluble ligand, m-TPPTC, was highly effective for such a reaction in the biphasic water/toluene system (Eq. 4.51). The reaction was completely stereo-and regioselective. In addition, the catalyst did not lose any activity... 

Scheme 5.3-35 Pd-catalyzed dimerization of methylacrylate in the diphasic system[BMiM][BF4]/toluene.

Duxin, N., Brun, N., BonviUe, R, CoUiex, C., Pileni, M.P. Nanosized Fe-Cu-B alloys and composites synthesized in diphasic systems. 1. Phys. Chem. B 101, 8907-8913 (1997)... 

Dialysis is a cleanup method in which the analyte passes from one solution to another through a membrane while impurities do not transfer. The process can be set up to remove either low-molecular-weight or high-molecular-weight interferences. As examples, dialysis was used to extract the mycotoxin patulin from apple juice using ethyl acetate in a diphasic system, and to remove... 

Laplace law. The big law in these domains, which span from capillarity to wetting, through diphasic systems, is Laplace s law. This law is demonstrated here in the most general case, with a curvature of the interface separating the two phases that can be of any shape. Physically speaking, this law assumes a simple coupling relationship between efforts. 

Abstract A review is presented on the effects of the molecular structure of polymers on their properties. The influence of such variables as molecular weight, macromolecular conformation and crystallisation, amorphous states and the glass transition temperature are discussed. Diphasic systems are explored and the properties of thermoplastic and thermosetting polymers are investigated. 

If such a state equation gives three roots, the lowest value of the molar volume obtained corresponds to the molar volume of the hquid and the highest value corresponds to the molar volume of the gas. The intermediate value has no physical sense and the P(T) curve between the two extreme roots is replaced by a horizontal line, since it represents a diphasic system in a hquid-vapor eqnihbrium and in this case the pressure is no longer a function of volume, it is constant while the two phases are present. 

Figure 9.10 Enantioselective reduction and deracemization using Pichia ucozfma in water/organic solvent diphasic systems.

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