Stylized Mechanisms A Typical Rice-Herzfeld Mechanism

12 Stylized Mechanisms A Typical Rice-Herzfeld Mechanism [Pg.221]

In any mechanistic study the proposed mechanism must fit the observed kinetics, and clues as to likely fits could help eliminate unnecessary trial and error analyses. In 1934 Rice and Herzfeld proposed a set of mechanisms from which systematic rules were inferred relating the observed order to the type of initiation and termination steps. These mechanisms are highly stylized, but even today they often form the basis for the interpretation of the thermal decomposition of organic molecules, though extra steps often have to be added. They demonstrate how only a small change in mechanism will alter the kinetic features in a systematic way. [Pg.221]

However, minor products, P3, P4 and P5 are also formed, along with radical intermediates R RJ, and R. A possible schematic mechanism is [Pg.222]

R is formed in initiation, but as it is not involved in propagation it is not a chain carrier and will be removed in some subsequent reaction not associated with the chain. M is a third body whose significance will be explained below (Section 6.12.4). [Pg.222]

A steady state treatment shows the overall order to depend on the type of step in which the radical is formed, and also on which termination step is dominant. [Pg.222]

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