L-Ethyl-4-carbomethoxy-pyridinyl

Stable radicals can be isolated in pure form, e.g., l-ethyl-4-carbomethoxy-pyridinyl ( ) Griller and Ingold have proposed the term penristent to refer to long-surviving radicals. (Neither stable nor persistent can be defined precisely since exposure of the radicals to different reactants will l wi to different... 

TABLE I. Rate Constants for the Reaction of l-Ethyl-4-carbomethoxy-pyridinyl Radical with Halides and Polyhalides at 25 C... 

In the course of an attempted titration of l,l -trimethylene-bis-(4-carbomethoxypyridinium) ion (++) with l-ethyl-4-carbomethoxy-pyridinyl radical ( )> we discovered that these species formed a strong complex, quite stable in acetonitrile at room tenq)erature. (Eq. 13). Epr spectra exhibited exchange narrowing and possibly two overlapping spectra, but the most significant property of the complex was a near infrared band 1360 nm (e g 1500)) which... 

Simple pyridinyl radicals, Py, like those derived from 1-ethyl-4-carbomethoxy-pyridinium ion through l reduction, have proven useful for the investigation of properties of radicals, including complexes, and the study of the mechanisms of their reactions. Discoveries include (a) distinction between atom-transfer and electron-transfer reactions by means of solvent effect on rate constants, (b) intramolecular radical complexes (ir-mers) within pyridinyl diradicals and pyridinyl diradical metal halide complexes, (c) occurrence of either electron-transfer or dimerization between pyridinyl radicals in water according to structure and (d) con5)lexation between pyridinium ions and pyridinyl radicals. Consideration of actual and potential biological roles for pyridinyl radicals is aided by these discoveries. 

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