A theoretical study of the gas-phase reactions of propadiene with NO3: mechanism, kinetics and insights

In this study, the conversion mechanisms and kinetics of propadiene (CH2 = C=CH2) induced by NO3 were researched using density functional theory (DFT) and transition state theory (TST) measurements. The NO3-addition pathways to generate IM1 (CH2ONO2CCH2) and IM2 (CH2CONO2CH2) play a significant role. P3 (CH2CONOCHO + H) was the dominant addition/elimination product. Moreover, the results manifested that one H atom from the -CH2- group has to be abstracted by NO3 radicals, leading to the final product h-P1 (CH2CCH + HNO3). Due to the high barrier, the H-abstraction pathway is not important for the propadiene + NO3 reaction. In addition, the computed k(tot) value of propadiene reacting with NO3 at 298 K is 3.34 x 10(-15) cm(3) per molecule per s, which is in accordance with the experimental value. The computed lifetime of propadiene oxidized by NO3 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.

Automated summary

The conversion mechanisms and kinetics of propadiene (CH2 = C=CH2) induced by NO3 were investigated using density functional theory (DFT) and transition state theory (TST). The addition pathways of NO3 to generate IM1 (CH2ONO2CCH2) and IM2 (CH2CONO2CH2) play a significant role, with P3 (CH2CONOCHO + H) being the dominant addition/elimination product. It was found that one H atom from the -CH2- group needs to be abstracted by NO3 radicals in order to form the final product h-P1 (CH2CCH + HNO3). The H-abstraction pathway is not important for the propadiene + NO3 reaction due to the high barrier. The computed k(tot) value of propadiene reacting with NO3 at 298 K is 3.34 x 10(-15) cm(3) per molecule per s, which agrees with experimental observations. The computed lifetime of propadiene oxidized by NO3 radicals was estimated to be 130.16-6.08 days at 200-298 K and an altitude of 0-12 km. This study offers insights into the transformation of propadiene in a complex environment.