A theoretical study of the gas-phase reactions of propadiene with NO(3): mechanism, kinetics and insights

In this study, the conversion mechanisms and kinetics of propadiene (CH(2)[double bond, length as m-dash]C[double bond, length as m-dash]CH(2)) induced by NO(3) were researched using density functional theory (DFT) and transition state theory (TST) measurements. The NO(3)-addition pathways to generate IM1 (CH(2)ONO(2)CCH(2)) and IM2 (CH(2)CONO(2)CH(2)) play a significant role. P3 (CH(2)CONOCHO + H) was the dominant addition/elimination product. Moreover, the results manifested that one H atom from the –CH(2)– group has to be abstracted by NO(3) radicals, leading to the final product h-P1 (CH(2)CCH + HNO(3)). Due to the high barrier, the H-abstraction pathway is not important for the propadiene + NO(3) reaction. In addition, the computed k(tot) value of propadiene reacting with NO(3) at 298 K is 3.34 × 10(−15) cm(3) per molecule per s, which is in accordance with the experimental value. The computed lifetime of propadiene oxidized by NO(3) radicals was assessed to be 130.16–6.08 days at 200–298 K and an altitude of 0–12 km. This study provides insights into the transformation of propadiene in a complex environment.