Reaction Mechanism of One-Pot Synthesis of Dinitro Pentamethylene Tetramine

Dinitro pentamethylene tetramine (DPT) is an important precursor of octogen (cyclotetramethylene-tetranitramine. Starting from urea without isolation of intermediates, DPT was obtained by nitration, hydrolysis and Mannich condensation, in total yield of 63.2%. The reaction mechanism of one-pot synthesis of DPT was studied by isolating and capturing intermediates, and isotope tracing experiments. The stable intermediates dinitrourea, nitramide and bis(hydroxymethyl)nitroamine were isolated, and the active intermediate 1-nitro-hexahydrotriazine was captured by benzenesulfonyl chloride. The H-2 labeled DPT (DPT-D) was synthesized by the reaction of CD2O with NH3 and bis(hydroxymethyl)nitroamine. The analysis results from H-1 NMR and MS of DPT-D indicate that in the course of the reaction bis(hydroxymethyl)nitroamine is decomposed into CH2O and nitramide, and the small molecule species make up randomly to form triazine, then DPT.