from first principles PP-I-1

PP-I-11Catalytic Transformations During Thermal Decomposition of SomeAliphatic Nitro CompoundsShamov A.G., Nikolaeva E.V., Tsyshevsky R.V., Khrapkovskii G.M.Kazan National Research Technological University, Kazan, Russiashamov@kstu.ruPresent report represents results of theoretical study regarding secondary steps ofnitromethane (NM), nitroethylene (NE) and methylnitramine (MNA) thermal decomposition.It was found that catalytic and autocatalytic reactions are of great importance in theseprocesses. It is well known that homolytic C-NO 2 bond cleavage is the predominant primaryreaction pathway for NM thermal decomposition. Nevertheless, there is still uncertainty whileinterpreting entire decomposition process due to the lack of reliable data concerningsecondary reaction steps. We have revealed the important role of reactions proceedingthrough formation of aci-form of NM. Effect of catalytic and autocatalytic reactions involvingaci-form of NM in the course of NM decomposition have been studied.It was determined that the primary act of NE thermal decomposition is the isomerization to4Н-1,2-oxazete-2-oxide involving following decomposition via multistage diradicalmechanism. We have studied decomposition of bimolecular complex of nitroethane(NEthane) proceeding through multistage autocatalytic mechanism. The basic stages ofprocess have significantly lower activation barriers compare to monomoleculardecomposition. Studied mechanism can explain the possibility of increasing of reaction ratesfor decomposition in liquid phase.The new mechanisms were studied also for MNA. Gas-phase decomposition involves aciformformation. Further transformations of aci-form was investigated including catalytic andautocatalytic reaction pathways. Formation of two aci-forms of MNA was concluded to be themost energy-efficient channel during the interaction of MNA and its aci-form. This processmay be assumed as the most favorable mechanism of thermal decomposition in liquid-phase.127