Effects in kinetics

E. V. Albano. Finite-size effects in kinetic phase transitions of a model reaction on a fractal surface Scahng approach and Monte Carlo investigation. Phys Rev B 42 R10818-R10821, 1990. 

Salt effects in kinetics are usually classified as primary or secondary, but there is much more to the subject than these special effects. The theoretical treatment of the primary salt effect leans heavily upon the transition state theory and the Debye-Hii ckel limiting law for activity coefficients. For a thermodynamic equilibrium constant one should strictly use activities a instead of concentrations (indicated by brackets). 

It has long been appreciated that the occurrence of compensation effects in kinetic data could result from the specific selection of reaction systems for study on the criterion that conveniently measurable rates are obtained within the same selected temperature interval (4,5). If either A or varies significantly within such data, appropriate magnitudes of k are only possible if there is a measure of compensation. 

Radial dispersion has negligible effect in kinetic regime but lowers e in diffusion regime. Pore length dispersion has less effect. 

Before coupling, excess nitrous acid must be destroyed. Nitrite can react with coupling components to form nitroso compounds causing deliterious effects on the final dyestuff. The presence of nitrite can be detected by 4,4,-diamino-diphenylmethane-2,2,-sulfone [10215-25-5] (Green reagent) or starch—iodide. Removal of nitrite is achieved by addition of sulfamic acid or urea [57-13-6], however, sulfamic acid [5329-14-6] has been more effective in kinetic studies of nine nitrous acid scavangers (18). 

Historically the underestimation of the role and magnitude of the self-cooling effect in kinetic studies of thermal decomposition has turned out to be one of the most important reasons which hindered interpretation of the T-S effect and, to some extent, the compensation effect, and promoted some misconceptions [19, 26-28], based on the confidence in infallibility of the second-law method in determination of thermochemical parameters (the enthalpy and entropy for decomposition reactions). 

Finucane, D. et al. Perturbation analysis of second-order effects in kinetics of oil shale pyrolysis. Fuel 56 (1977) p. 65-68. 

Moore, S.B., Carr, R.W. (1977) Molecular Velocity Distribution Effects in Kinetic Studies by Time-resolved Mass Spectrometry. Int. J. Mass Spectrom. Ion Phys. 24 161-171. 

Today we can understand it in terms of activity effects in kinetics. 

Salt Effects. The solution to the problem came largely from investigations of salt effects in kinetics. The addition of foreign salts, which do not have an ion in common with any ion directly involved in the reaction, is often found to have an important kinetic effect. At first the explanations were given in terms of positive or negative catalysis, but this idea proved to be unhelpful. It is best instead to regard salt effects as environmental effects and to explain them in terms of the activity coefficients of the reacting species. 

A commentary on diastereoselectivity in chemical glycosylation reactions has dismissed molecular orbital explanations that invoke stereoelectronic effects analogous to the anomeric effect in kinetically controlled reactions. ... 

Muriel-Delgado F, Jimenez R, Gomez-Herrera C, Sanchez F. Use of the Bronsted equation in the interpretation of micellar effects in kinetics (II). Study of the reaction [Fe(CN)(5)(4-CNpy)](3-)+CN-reversihle arrow Fe(CN)(6)(4-)+4-CNpy in CTAQ micellar solutions. Langmuir. 1999 15 4344-4350. 

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