Mechanisms and Kinetics of the Synthesis of FOX-12†

Abstract

The mechanisms of the synthesis of N-guanylurea-dinitramide( FOX-12) were investigated at B3 LYP / 6-311G( d,p) level. The geometries of the reactants,intermediates,transition states,and products were optimized,respectively. The relevance between every transition state and the corresponding reactant /product was confirmed via the intrinsic reaction coordinates( IRC). The single-point energies of the species at the optimized geometries were corrected at the MP2 / 6-311++G( 3df,3pd) level. It was shown that the binitroamide acid( HDN) could be obtained by both channel A1,in which —SO3was preferentially replaced by nitronium( NO+2),and channel B,in which —H was preferentially replaced by NO+2,while the channel A1 was found to be the dominant channel. Then the intermediate product of HDN could be converted to the targeted product of FOX-12 via the channel of either HDN→FOX-12 or HDN→amonium dinitramide( ADN) →FOX-12,while the latter was tend to be considered as the better approach. The rate constants were calculated at temperature ranges of 200—400 K by means of the classical transition state theory( TST) and the canonical vibration transition state theory( CVT) corrected by the small-curvature tunneling( SCT). And the three-parameter Arrhenius expressions of rate constants were also provided. It was expected that the present study may provide a theoretical basis to the research and engineering amplification of FOX-12 as well as other energetic materials.