Mechanisms and Kinetic Parameters for the Gas-Phase Reactions of 3-Methyl-3-buten-2-one and 3-Methyl-3-penten-2-one with Ozone

Abstract

Ozonolysis of unsaturated ketones is a common atmospheric chemical process that plays a significant role in controlling the atmospheric budget of OH and O 3 , organic acids, and secondary organic aerosols (SOA). In this work, the detailed reaction mechanism and rate coefficients for the reactions of O 3 with two unsaturated ketones, 3-methyl-3-buten-2-one (MBO332) and 3-methyl-3-penten-2one (MPO332), were investigated by using density functional theory (DFT) and Rice−Ramsperger−Kassel−Marcus (RRKM) theory. The results indicate that the major products are butanedione and formaldehyde for MBO332, and butanedione and acetaldehyde for MPO332. Possible reaction mechanism and thermodynamic parameters of some complex stable Criegee intermediates (SCIs) RR′COO were also be investigated in this study. Some organic peroxides can be regarded as the main products for the further reactions of SCIs. The rate constants calculated with O 3 are 2.59 × 10 −16 cm 3 molecule −1 s −1 and 2.28 × 10 −16 cm 3 molecule −1 s −1 for MBO332 and MPO332 at 298 K and 1 atm. The total rate constant is negatively correlated with temperature (200−400 K) and positively correlated with pressure. The atmospheric half-lives of MBO332 and MPO332 based on O 3 are estimated.

Gas-phase reactivity of acyclic α,β-unsaturated carbonyls towards ozone

“…The kinetics of 3-methyl-3-penten-2-one with ozone has been theoretically 14 and experimentally 15 investigated, once each. The theoretical investigation by RRKM theory 14 yielded a rate coefficient of 2.28 Â 10 À16 cm 3 molecule À1 s À1 , which is around three times larger than the value of (80.1 AE 18.7) Â 10 À18 cm 3 molecule À1 s À1 determined in this work. On the other hand, the rate coefficient reported by Wang and co-workers 15 is 50% smaller.…”

“…6,7 The kinetics of the ozonolysis reactions of a moderate number of a,b-unsaturated carbonyls have been studied using both the absolute and relative rate method. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, the systematic analysis of their reactivity towards O 3 is at best at the beginning. 28 It is quite common to relate a target compound to the reactivity of its core structure in order to explain and/or predict its behaviour towards one of the atmospheric oxidants.…”

Study on the Formation of Secondary Organic Aerosol by Ozonolysis of Citral in the Atmosphere

“…In atmospheric chemistry, one of the most important reactions is considered to be the reaction with H2O because of its high abundance. Previous theoretical and experimental studies have shown that the reaction between CIs and H 2 O occurs via three main reaction channels (Qi and Chao, 2007;Wang et al, 2019). The pathway to produce organic peroxides likely to be thermodynamically and kinetically advantageous compared with the other two pathways.…”

“…model chemistries, including heavy-atom transfer (HATBH6), nucleophilic substitution (NSBH6), unimolecular and association (UABH6), and hydrogen-transfer (HTBH6) reactions. The selected functional M06-2X/6-31+G(d,p) was proven to be reliable and appropriate for the configuration optimization and thermodynamic calculation of ozonolysis (Sun et al, 2018;Wang et al, 2019). At the same level of theory, frequency calculations were performed to obtain zero-point energy corrections.…”

Kinetics and Thermodynamics of Reactions Involving Criegee Intermediates: An Assessment of Density Functional Theory and Ab Initio Methods Through Comparison with CCSDT(Q)/CBS Data

“…11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28 However, for computational studies exploring reaction mechanisms involving larger CIs density functional theory (DFT) provides the only practical avenue, and a number of such investigations have been reported in recent years. 11,14,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43 It is therefore of interest to assess the performance of ab initio and DFT methods for their ability to accurately calculate the reaction energies and barrier heights of chemical reactions involving CIs. In the present work, we introduce a representative benchmark database of 22 ring-closing reactions involving CIs (a.k.a.…”