Probing the Reaction Mechanisms Involved in the Decomposition of Solid 1,3,5-Trinitro-1,3,5-triazinane by Energetic Electrons

Identification of Elusive Keto and Enol Intermediates in the Photolysis of 1,3,5-Trinitro-1,3,5-Triazinane

Enols have emerged as critical reactive intermediates in combustion processes and in fundamental molecular mass growth processes in the interstellar medium, but the elementary reaction pathways to enols in extreme environments, such as during the decomposition of molecular energetic materials, are still elusive. Here, we report on the original identification of the enol and keto isomers of oxy-s-triazine, as well as its deoxygenated derivative 1,3,5-triazine, formed in the photodecomposition processes of 1,3,5-trinitro-1,3,5-triazinane (RDX)-a molecular energetic material. The identification was facilitated by exploiting isomer-selective tunable photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) in conjunction with quantum chemical calculations. The present study reports the first experimental evidence of an enol intermediate in the dissociation domain of a nitramine-based energetic material. Our investigations suggest that the enols like 1,3,5-triazine-2-ol could be the source of hydroxyl radicals, and their inclusion in the theoretical models is important to understand the unprecedented chemistry of explosive materials.

Origin of ammoniated phyllosilicates on dwarf planet Ceres and asteroids

The surface mineralogy of dwarf planet Ceres is rich in ammonium (NH₄⁺) bearing phyllosilicates. However, the origin and formation mechanisms of ammoniated phyllosilicates on Ceres’s surface are still elusive. Here we report on laboratory simulation experiments under astrophysical conditions mimicking Ceres’ physical and chemical environments with the goal to better understand the source of ammoniated minerals on Ceres’ surface. We observe that thermally driven proton exchange reactions between phyllosilicates and ammonia (NH₃) could trigger at low temperature leading to the genesis of ammoniated-minerals. Our study revealed the thermal (300 K) and radiation stability of ammoniated-phyllosilicates over a timescale of at least some 500 million years. The present experimental investigations corroborate the possibility that Ceres formed at a location where ammonia ices on the surface would have been stable. However, the possibility of Ceres’ origin near to its current location by accreting ammonia-rich material cannot be excluded.

The authors here propose a chemical reaction that forms ammoniated phyllosilicates on Ceres. This process could trigger at a very low temperature, suggesting Ceres evolution in a region different from its current location.