The decisive role of pericyclic reactions in the thermal decomposition of organophosphorus compounds

The understanding of the thermal decomposition chemistry chemical warfare nerve agents is largely limited by scarcity kinetic data. Because high toxicity these molecules, experimental determination their properties very difficult. In present work, a comprehensive detailed model for sarin and some simulants, i.e. di-isopropyl methyl phosphonate (DIMP), diethyl methylphosphonate (DEMP), triethyl phosphate (TEP) were developed, containing possible molecular radical pathways. importance unimolecular pericyclic led to evaluate precisely rate constants reactions with level theoretical calculations. QCISD(T)/cc-PV∞QZ//B2PLYPD3/6–311+G(2d,d,p) theory was selected after benchmark. contribution hindered rotors included 1D-HR-U approach. Tunneling taken into account H-atom transfer. Transition state used calculate high-pressure limit pressure dependent calculated using Master Equation modeling. validated against pyrolysis oxidation data available in literature. Flux analyses showed that whatever conditions are, first step studied phosphorus compounds are eliminations leading successive decompositions, whereas bond-breaking or abstraction remain negligible, even at temperature.