Reaction Kinetics

Abstract

It is not possible within the space limitations of this chapter to make a thorough review of all areas in chemical kinetics, nor to be complete within each area. Among the phases which have been covered fairly thoroughly are oxidation-reduction reactions, and the kinetics of !<ubstitution at metal ion centers. This emphasis came naturally since the reviewer has had a continuing interest in these fields, but it was admitted only because a rapid growth of activity in them seems certain. Other fields which seem likely to invite increased attention are: elementary free radical reactions, induction periods, phenomena in shock waves, and rates in nonpolar solvents. The important field of kinetics of enzyme reactions has been omitted entirely.It is hoped that the hiatus wiII help stimulate a succeeding reviewer to do a thorough job in this interesting field. GENERAL THEORETICAL PAPERSSeveral papers have dealt \\'ith the theory of the decomposition of activated complexes. Benson (1) has continued the application and extension of Slater's (2) trea tment of the adiabatic decomposition of unstable mole cules, discussing bimolecular as well as unimolecular processes, and applying the equations developed to the pressure dependence of the first-order specific rate in unimolecular reactions, and to the recombination of atoms and radicals. Marcus (3) has offered a more general derivation of the equations of Marcus & Rice (4) describing unimolecular decomposition, and has applied (5) the treatment to the decomposition of activated complexes resulting from the recombination of free radicals. Johnston (6), analyzing the gener alized Lindeman mechanism for unimolecular reactions, has defined the relation of the rate characteristics in the high concentration region to those of the low concentration region.The kinetic properties of systems involving consecutive reactions have received considerable attention. Benson (7) has discussed induction periods in such systems, Skrabal (8), the theory of periodic reactions, Hinshelwood (9) the kinetics of autosynthetic systems, Natta & Mantica (10) the dis tribution of products in consecutive competitive reactions, and Frost & Schwemer (11) have described a method for evaluating rate constants from data for competitive consecutive second-order reactions. Skrabal (12) has defined the concept of independent reactions, given it a mathematical formulation and shown how it applies to the kinetics of complex systems.