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The subject invention relates to a method of synthesizing nitroxides from secondary amines. This method uses a suitable dioxirane compound such as dimethyldioxirane (DMD), which is relatively stable and simple to synthesize, as the oxidizing agent. A quantity of a secondary amine having no hydrogen atoms directly attached to the alpha carbon atoms is mixed with a 2x molar ratio of the dioxirane. In a first reaction, the secondary amine is oxidized to form a hydroxylamine; in a second reaction, the hydroxylamine is further oxidized to form a nitroxide. When the dioxirane loses an oxygen atom it converts into a ketone; for example, dimethyldioxirane is converted into acetone. This is very convenient, since the ketone byproduct is a solvent that can be easily removed after the reaction without causing interfering reactions. This method provides a simple, highly selective, rapid reaction with very high yields. It can be carried out in a single reaction vessel and can be used with a wide variety of secondary amines (including secondary amines having more than one amine group) to create a corresponding variety of nitroxides.
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The Curators of the University of Missouri, Columbia, MO
Murray, Robert W. and Singh, Megh, "Synthesis of nitroxides using dioxiranes" (1992). UMSL Patents. 26.