Potassium systems, kinetic parameters

Table I. Kinetic Parameters of Bacterial Potassium Transport Systems ...

Griffin and Jurinak (1974) calculated pseudothermodynamic parameters for phosphate interactions with calcite using reaction-rate theory. Gonzalez et al. (1982) applied reaction-rate theory to a treatment of adsorption-desorption processes on an Fe-selica gel system. In 1981, Sparks and Jardine applied reaction-rate theory to kinetics of potassium adsorption and desorption in soil systems for the first time (Table 2.5). 

Most reactions that have been investigated using PTC in supercritical fluids have been solid-SCF systems, not liquid-SCF. The first published example of PTC in an SCF is the displacement reaction of benzyl chloride 1 with potassium bromide in supercritical carbon dioxide (SCCO2) with 5 mol % acetone, in the presence of tetraheptylammonium bromide (THAB) [19-20] (Scheme 4.10-1) to yield benzyl bromide 2. The effects on reaction rate of traditional PTC parameters, such as agitation, catalyst type, temperature, pressure, and catalyst concentration were investigated. The experimental technique is described below. PTC appeared to occur between an SCF phase and a solid salt phase, and in the absence of a catalyst the reaction did not occur. With an excess of inorganic salt, the reaction was shown to follow pseudo-first order kinetics. 

They also found that the Erofeev equation described the observed kinetics much better than other simple kinetic equations. Yufit and Zinovyev [212] compared the kinetic study of nucleophilic substitution under PTC conditions in liquid-liquid and solid-liquid systems. They observed the effect of initial exponential burst (IB) on the kinetic curve in the reaction with solid salts for the Sn2 reaction of 2-octylmesylate with potassium halides under PTC conditions. In their study, they assumed that the active sites on which the reaction occured were present on the solid surface through the formation of complexes of salts, catalysts, and substrate [212-215]. They also concluded that the phenomenon of IB was characterized by the first-order dependence on the initial stage of conversion and by zero-order dependence up to high conversion. Therefore, the kinetic equation for the reaction becomes a sum of linear and exponential terms with correlated parameters A and B... 

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