Atmospheric degradation of 3-ethoxy-1-propanol by reactions with Cl, OH and NO3

Theoretical investigation on degradation of CH[triple bond, length as m-dash]CCH2OH by NO3 radicals in the atmosphere

A detailed computational investigation is executed on the reaction between NO3 and CH[triple bond, length as m-dash]CCH2OH at the CCSD(T)/cc-pVTZ//B3LYP/6-311++G(d,p) level. Addition/elimination and H-abstraction mechanisms are found for the NO3 + CH[triple bond, length as m-dash]CCH2OH reaction, and they could compete with each other. The most feasible addition/elimination pathway through a series of central-C addition, 1,4-H migration to generate intermediates IM1 (CHCONO2CH2OH) and IM3 (CH2CONO2CH2O), and then IM3 directly decompose into product P2 (CH2CONO2CHO + H). The dominant H-abstraction pathway is abstracting the H atom of the -CH2- group to generate h-P1 (CHCCHOH + HNO3). RRKM-TST theory was used to compute the kinetics and product branching ratios of the NO3 + CH[triple bond, length as m-dash]CCH2OH reaction at 200-3000 K. The rate constants at 298 K are consistent with the experimental values. The lifetime of CH[triple bond, length as m-dash]CCH2OH is estimated to be 59.72 days at 298 K. The implicit solvent model was used to examine the solvent effect on the total reaction. Based on the quantitative structure-activity relationship (QSAR) model, the toxicity during the degradation process is increased towards fish, and decreased towards daphnia and green algae.

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[double bond, length as m-dash]C[double bond, length as m-dash]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 × 10^-15 cm³ 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.