Novel Reagents for N-NO2 Scission.

Two novel approaches to N-NO2 bond scission in military nitramines under gentle, environmentally benign conditions were proposed for the Phase I program and have been successfully demonstrated. These approaches to N-denitration were based on mechanisms of electron transfer hydrogenolysis by certain dihydropyridine derivatives, which was demonstrated on both tetryl and HMX as model aromatic and heterocyclic nitramines, respectively and catalytic transfer hydrogenolysis, which employed hydrazine as a gentle reagent which denitrated HMX as a model nitramine. In the first system, N-NO2 bond scisssion in tetryl was demonstrated as the predominant transformation in its reaction with 1-benzyl-1,4-dihydronicotinamide BNAH, a commercial dihydropyridine derivative, resulting in N-methylpicramide as the major product. In the HMX-BNAH system, HMX was definitively shown to be denitrated, and spectroscopic evidence was obtained for its conversion to hexamethylenetetramine, the expected product of its denitration. Similarly, in palladium-catalyzed reactions between HMX and hydrazine, HMX was unequivocally denitrated. The products produced depended on reaction conditions. The initial intermediate is the reactive species formaldazine under oxidizing conditions with catalyst, this reacts further to form 4-amino-4H-1,2,4-triazole as a final product.