Semiquantitative kinetic studies

A study of acid-base behaviour and of absorption spectra of [Pd(OH2)4] + and of palladium(ii)-amine complexes has produced some semiquantitative kinetic observations. ... 

The studies described above represent what is hoped is a comprehensive coverage of quantitative kinetic studies of insertion and migration reactions that have been reported. There are many other studies that relate to a very wide variety of insertion and migration processes from which mechanistic and semiquantitative kinetic inferences can be obtained, but space precludes their discussion here. Some rather arbitrarily chosen examples are appended. ... 

Kinetic study has been one of the best mechanistic (reaction) tools to establish the most refined reaction mechanisms. In an attempt to establish such a reaction mechanism, kinetic experimental data on the reaction rate are obtained under a set of reaction conditions that could be explained by a kinetic equation derived on the basis of a proposed reaction mechanism. The study is repeated to obtain kinetic data under slightly or totally dilferent reaction conditions, and if these kinetic data fail to fit the kinetic equation derived on the basis of the earlier reaction mechanism, a further refinement in the mechanism is suggested so that the present and earlier kinetic data could be explained mechanistically. A similar approach has been used to provide quantitative or semiquantitative explanations for the micellar effects on reaction rates. Let us now examine the micellar kinetic models developed so far for apparent quantitative explanations of the effects of micelles on reaction rates. 

The results of the experiments presented in this paper demonstrate that the migration of nuclides in geologic media can be studied experimentally and treated in at least a semiquantitative fashion using kinetic and partitioning data. The ARDISC model is a useful aid in analyzing nuclide migration data obtained in laboratory experiments. But the ARDISC model is limited to first-order sorption kinetics. 

The quantitative high-temperature chemistry of chlorine oxysalts is rather underdeveloped. There are very few thermodynamic data for these compounds above 298 K. Even when they exist, they must be applied cautiously, since there may be kinetic rather than thermodynamic factors that determine decomposition behavior. Although the thermal decomposition of a few compounds has been studied very carefully (e.g., the KC104 literature extends back for more than a hundred years because of the compound s use in explosives), the bulk of the available information is qualitative or semiquantitative. In recent years this has changed somewhat with increasing use of automated techniques such as DTA and TGA. Many of the reactions are complex, with mechanisms frequently controversial and not completely worked out. Decomposition products may depend on experimental conditions e.g., salts are frequently prepared by dehydration of their hydrates, and residual water may affect the course of the decomposition. 

The reaction mechanism proposed above seems to be the most probable from the kinetic point of view, but must be treated only as a semiquantitative approach until the role of the ion pair dynamics has been exactly recognized. Systematic studies (similar to those performed in acetonitrile solutions) of solvent polarity and viscosity may provide the decisive answer, probably also making possible a more quantitative description with estimates of all the kinetic parameters. 

This review is organized to cover the basic features of simple electron transfer reactions. The first three sections develop background material on the thermodynamics, kinetics, and microscopic theory of electron transfer reactions. More general, semiquantitative treatments of these topics are presented, with the objective of introducing the conceptual approaches used to characterize electron transfer processes. The fourth section describes experimental studies on two electron transfer systems, selected from both physiological and nonphysiological... 

A quantitative description of relations between structural parameters of solid catalysts or substrates on one side and reaction rates or adsorption equilibria on the other side, even if valid only in limited areas, may form an important step in the development of a general theory of catalysis. Some years ago, Boudart 1) noticed that such correlations in heterogeneous catalysis can be divided into two broad classes. In the first type a series of catalysts is tested by means of a standard reaction and some kinetic parameter is related to a property of the solid catalyst. In correlations of the second type, the reactivity of a series of compounds is studied on a single catalyst and some kinetic parameter is related to a property of the reacting molecules. Boudart pointed out that correlations of the first type are more frequent in the literature than those of the second type. He also presented some examples of both types. Correlations between the substrate structure and its reactivity were qualitative or semiquantitative. 

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