Kinetic sodium ions

Specific catalysis by sodium ions is also found in the oxidation of iodide ion by octacyanomolybdate(V) which otherwise shows simple, second-order kinet-ics with E = 5.68 2.57 kcal.mole" and A5 = —39 8.5 eu and /c2 = 3.52+0.13 l.mole sec , at 25.7 °C and fi = 0.1 M. Mo(IV), which is produced stoichiometrically exerts slight retardation upon the reaction. An outer-sphere one-electron transfer is proposed. 

Cools, A. A. Janssen, L. H. M., Influence of sodium ion-pair formation on transport kinetics of warfarin through octanol-impregnated membranes, J. Pharm. Pharmacol. 35, 689-691 (1983). 

A circuit that uses a differential amplifier to maintain constant membrane potential by electronically balancing the ion channel current. This method allows the experimenter to analyze action potentials of excitable membranes resulting from an initial transient rise in sodium ion permeability followed by a transient rise in potassium ion permeability The technique is especially valuable for studying kinetic properties of voltage-gated channels as well as voltage-dependent channels. See Membrane Potential Patch Clamp Methods... 

Ikeda, T., Sasaki, M., and Yasunaga, T. (1983). Kinetic studies of ion exchange of alkylammonium ion for sodium ion in aqueous suspensions of zeolite 4A using the pressure-jump method. J. Phys. Chem. 87, 745-749. 

Bosnar, S., Antonie, T., Bronic, J. and Subotic, B. Mechanism and kinetics of the growth of zeolite microcrystals. Part 2 Influence of sodium ions concentration in the liquid phase on the growth kinetics of zeolite A microcrystals, Microporous Mesoporous Mater., 2004, 76, 157-165. 

In constrast, kinetic regioselectivity does not usually correspond to the thermodynamic stability ratio between the two enolates. Indeed, when the ketone is ionised in protic solvents which make equilibration possible, the more substituted enolate is formed (e.g. [45] and [46] are in the ratios 10 90 and 40 60 for the lithium and sodium ion pairs, respectively, in dimethyl ether) (House, 1972). This means that the hyperconjugative effect, which is predominant in the enolate, is less important than inductive and steric effects in the transition state, a result which is in agreement with the carbanion character. The regioselectivity of preparative enolate formation in organic solvents has been reviewed by D Angelo (1976). 

Table 5-21 shows that the addition of even small proportions of EPD solvents affeets the reaetion rate markedly. The rate acceleration thus obtained is produced by a specific solvation of sodium ion, which tends to dissociate the high-molecular mass ion-pair aggregate of the sodio-malonic ester that exists in benzene solution (degree of aggregation n is equal to 40... 50 in benzene). This indicates that the kinetically active species is a lower aggregate of the free carbanion. Further evidence for a specific cation solvation is derived from the six-fold rate difference observed in tetrahydrofuran (fir = 7.6) and 1,2-dimethoxyethane (fir = 7.2), despite the fact that these two solvents possess nearly equal relative permittivities. The latter solvent is able to solvate sodium ions in the manner shown in Eq. (5-127). Especially noteworthy is the high reactivity exhibited on the addition of dicyclohexyl[18]crown-6. In benzene solution containing only 0.036 mol/L of this crown ether, the alkylation rate is already equal to that observed in neat 1,2-dimethoxyethane [351]. 

Not only do these studies support the presence in blood platelets of receptors with two distinct binding affinities but s concept is also supported by earlier functional evidence that thrombin-induced platelet activation is mediated by two distinct pathways which differ in their sensitivity to proteolysis, their requirement for sodium ions, in the need for receptor occupancy and in the role of G proteins (reviewed in ). Furthermore, kinetic studies demonstrated that both ligand-receptor and proteolytic interactions occur in thrombin-induced platelet activation. Thus, foe preponderance of evidence supports foe view that two different types of receptor are involved in foe interaction of thrombin with platelets. The major question is, however, what is foe nature of these two receptors ... 

Removal of dissolved inorganic impurities from methanol Is of Interest from the point of view of utilization of methanol as an alternative to conventional fuels. Reports show that the corrosion rate of metal alloys used for turbines and fuel transportation is greater in methanol than in water in the presence of traces of chlorine and sodium ions ( , 10). Further, ion complexes in trace quantities have been observed in methanol and there is concern that they could alter the reaction kinetics for processes which use methanol as a feedstock or reaction medium (11). Methanol that Is used as a feedstock In the production of single cell protein could be sterilized as well as purified of heavy metals by reverse osmosis which can be integrated in the design of these processes. 

A theoretical study of dimeric ion-pair aggregates of isomeric lithioacetaldimines and an ah initio study of the potential energy surfaces of isolated aldimine anions, their monomeric lithium and sodium ion-pairs and mechanistic consequences have been described. Knorr and Low demonstrated that metallation occurs rapidly and quantitatively, that protonation of the imine (85) is a kinetically controlled process favouring the formation of the -isomer about the C=C bond (86X that the anion is configuration-ally stable under the conditions generally used for its formation and that the -anion... 

Development of the slow tail current during a depolarizing pulse was taken as a measure of the rate at which the sodium channels are modified. It had a fast and a slow phase, and the latter disappeared after removal of sodium channel inactivation with pronase. Based on these and other results, a kinetic scheme was developed (Figure 2). Tetramethrin modifies the sodium channel in both closed and open states, and the modified channel opens and is inactivated much more slowly than the normal channel (15). However, we have very recently shown that the apparent inactivation of the modified sodium channel is a result of depletion of sodium ions in the periaxonal space (20). Figure 2 incorporates the revised version of the kinetic scheme. 

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