Ionic compounds rate-determining step

The rate-determining step in ionic hydrogenation is the protonation of the C=C bond . The unsaturated substrate must be capable of forming a stable carbocation by protonation with CF3CO2H which strongly limits the application of this reaction. Unsaturated compounds which are branched at the alkenic carbon atom can be easily reduced -, but unbranched compounds are not reduced under conditions of ionic hydrogenation reaction - -. 

Conrotatory cyclization of a series of pentadienyl cations to cyclopentenyl cations has been investigated. Cyclizations proceed stereospecifically and at virtually the same rate in solvents of markedly different ionic strengths. Of the compounds examined the slowest cyclization rate was exhibited by (310) and the fastest by (311) the relative rate of cyclization of (311) with respect to (310) was ca. 2 x 10 at 25 °C. However, the rate constants obtained are not identical with those for the electrocyclic process as two equilibria are thought to be involved prior to the rate-determining step. This is shown in the general case... 

The kinetics of radiation-initiated polymerizations follow in a relatively straightforward manner those of photolytic polymerization. The initiation rate is determined by the radiation intensity and the concentration and susceptibility of the compound that radiolyzes to yield the initiating species (ionic and/or radical). The final expression for Rp is determined by the exact details of the initiation, propagation, and termination steps. 

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