Process for preparing nitroxyls of sterically hindered amines

Claim 1

A process for the preparation of a nitroxyl of the formula ##STR7## wherein the nitrogen atom is flanked by two quaternary carbon atoms where E 1 and E 3 are independently alkyl of 1 to 5 carbon atoms of phenyl, E 2 and E 4 are independently alkyl of 1 to 5 carbon atoms, or E 1 and E 2 together or E 3 and E 4 together or both E 1 and E 2 together and E 3 and E 4 together are tetramethylene or pentamethylene, and T is a divalent group required to form a cyclic 5- or 6-membered ring, which comprises oxidizing an amine of the formula ##STR8## where E 1 , E 2 , E 3 , E 4 and T have the meanings given above, dissolved in an inert organic solvent with a hydroperoxide in the presence of from 0.001 to 0.1 mole percent, based on the hydroperoxide, of a catalyst selected from the group consisting of the metal carbonyls, the metal oxides, the metal acetylacetonates and the metal alkoxides where the metal is selected from groups IVb, Vb, VIb, VIIb and VIII of the periodic table, at a temperature of 0° to 200° C., with the mole ratio of hydroperoxide to amine being 50:1 to 1:10.