Reactions of a hydroximic acid chloride-a 3-imidazoline 3-oxide derivative-with nitrogen-containing nucleophilic reagents and preparation of stable amidoxime N-oxyl radicals

1. A hydroximic acid chloride, viz., 4-chloroximino-3-imidazoline 3-oxide, reacts with nitrogen-containing nucleophilic reagents to give amidoxime derivatives. The reaction with tert-butylhydroxylamine leads to an N-hydroxyamidoxime, the oxidation of which made it possible to preparatively isolate an amidoxime N-oxyl radical, viz., 4-(N-oxyl-N-tert-butylcarboxamidoximino)-1,2,2,5,5-pentamethyl-3-imidazoline 3-oxide. 2. Oxidation of the radical gives a nitroso nitrone, and alkylation gives only an O-alkylation product (an ether amidoxime N-oxyl), whereas the similarly constructed amidoxime reacts to give both an O-alkylation product (an ether amidoxime) and an N-alkylation product (a nitrone).