The diamagnetic scavengers spin traps

The pre-eminent advantage of C-nitroso-compounds as spin traps is that in the spin adduct the scavenged radical is directly attached to the nitroxide nitrogen. Consequently, the esr spectrum of the spin adduct is likely to reveal splittings from magnetic nuclei in the trapped radical, and these will greatly facilitate its identification. A simple example is presented in Fig. 2, which shows the spectrum of the spin adduct of the methyl radical with 2-methyl-2-nitroso- 

2 Esr spectrum of t-butyl methyl nitroxide, (MNP—Me ), in benzene, showing well resolved triple quartet pattern (Perkins et al., 1970) 

This example illustrates a further important point. To obtain easily interpreted spectra, the contribution to the splitting pattern from magnetic 

MNP has undoubtedly been the most widely used aliphatic nitroso spin trap, but there is one severe limitation on its use. It decomposes under the influence 

From the foregoing discussion it might seem fruitless to utilize MNP to investigate photochemical reactions. However, the monomer is transparent between ca. 270 and 550 nm, and by irradiating reaction mixtures in this window excellent results have been obtained without complications from DTBN formation (Leaver et al., 1969 Leaver and Ramsay, 1969a,b Torssell, 1970). This expedient is unfortunately not infallible, there being good evidence that aromatic ketones can photosensitize MNP dissociation (Ikeda et al., 1978). 

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