A general synthetic procedure has been found for the preparation of previously unreported nitroaromatic difluoramines. Nitroaromatic monoamines, such as picramide and its analogs, have been converted in high yield into the corresponding difluoramines in liquid hydrogen fluoride and in some cases in organic solvent, such as acetonitrile. Nitroaromatic diamines and triamines undergo similar fluorination reactions. Dinitro-substituted anilines fluorinate in good yield but the amine fluorination is accompanied by ring fluorination ortho to the difluoramino group. This reaction and general considerations of aromatic radical stabilization provide evidence for a radical mechanism operating in the fluorination reaction. In addition an unexpected product was obtained in the fluorination of 1,3-dinitro-2,4,6-triaminobenzene, which gave only a small amount of the corresponding trisdifluoramine and a major yield of 1,3-dinitro-2,4,6-tris(difluoramino)-1,2,3,4,5,6-hexafluorocyclohexane. Coupling rather than direct fluorination was obtained with pentafluoroaniline, which yielded bis(pentafluorophenyl) difluorohydrazine by a radical mechanism. The nitroaromatic difluoramino group between adjacent nitro groups was subject to attack by nucleophiles, such as ammonia and water. The synthesis, reaction, and properties of this novel class of compounds are discussed. © 1968, American Chemical Society. All rights reserved.
