Identification According to Correlation within Reaction Series

2 Identification According to Correlation within Reaction Series 

To get support for the postulation of ion-radical nature of the rate-determining step, one can plot the reaction rate constant values against the oxidation and reduction potentials of the reaction partners. When both plots occur to be linear, it will support the postulation of the ion-radical route. 

Another common approach consists of the comparison between the experimental rate constants and theoretical values calculated by the procedure developed by Marcus (1956), Marcus and Sutin (1985) as well as Hush (1958). This classical procedure is used widely. Premsingh et al. (2004) gave the relevant references and described a detailed procedure to analyze the ion-radical reaction between anilines and chromium (V) complexes of azomethyne derivatives. Lepage et al. (2003) studied transformation of para-substituted thioanisoles to corresponding methylarylsulfoxides 

As seen, the reaction yields both isomeric amines regardless of the halide position (5 or 6) in the initial molecule. In cases of chloro and bromo analogs, the ratio of 5- and 6-amino derivatives is 

Let us now consider the formation of aryl iodides from aryl diazonium salts and potassium iodide in methanol (Singh and Kumar 1972a, 1972b). Electron-donor substituents decelerate the process as compared with benzene diazonium (the substituent is hydrogen), whereas electron acceptor substituents accelerate it. Oxygen inhibits the reaction, and photoirradiation speeds it up. As the authors pointed out, in the case of 4-nitrobenzene diazonium, the reaction leads not only to 4-iodonitrobenzene but also to nitrobenzene, elemental iodine, and formaldehyde. All of these facts support the following sequence of events  

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