INVERTED SPIN-TRAPPING .4. APPLICATION TO THE FORMATION OF IMIDYL SPIN ADDUCTS FROM N-HALOIMIDES

The photochemically induced formation of imidyl spin adducts from N-ha loimides and four spin traps, 2-methyl-2-nitrosopropane (MNP), N-benzy lidene-tert-butylamine N-oxide (PBN), 1,1-diutylethylene (DTBE) and N- methylene-tert-butylamine N-oxide (MBN) has been studied. It is conclu ded that imidyl spin adducts from MNP, PBN and MBN are most likely for med via the radical cations of the spin traps, formed by reaction betw een the excited state of the spin trap and the N-haloimide. This type of reaction is a case of inverted spin trapping. For DTBE, this mechan ism can only be assigned by analogy, since this molecule cannot be exc ited by the light source employed. However, it does form imidyl adduct s by chemical or photosensitized (using 2,4,6-trianisylpyrylium ion or 9,10-dicyanoanthracene as the sensitizer) oxidation of DTBE solutions containing succinimidate anions, so even in this case inverted spin t rapping cannot be excluded.