Stabilization of the Simplest Criegee Intermediate from the Reaction between Ozone and Ethylene: A High-Level Quantum Chemical and Kinetic Analysis of Ozonolysis

Abstract

The fraction of the collisionally stabilized Criegee species CH2OO produced from the ozonolysis of ethylene is calculated using a two-dimensional (E, J)-grained master equation technique and semiclassical transition-state theory based on the potential energy surface obtained from high-accuracy quantum chemical calculations. Our calculated yield of 42 ± 6% for the stabilized CH2OO agrees well, within experimental error, with available (indirect) experimental results. Inclusion of angular momentum in the master equation is found to play an essential role in bringing the theoretical results into agreement with the experiment. Additionally, yields of HO and HO2 radical products are predicted to be 13 ± 6% and 17 ± 6%, respectively. In the kinetic simulation, the HO radical product is produced mostly from the stepwise decomposition mechanism of primary ozonide rather than from dissociation of hot CH2OO.

Identification and quantification of carbonyl-containing α-pinene ozonolysis products using O-tert-butylhydroxylamine hydrochloride

“…Along with OH, HO 2 may be formed during the multistep degradation of the Criegee intermediate (Nguyen et al 2015). In studies that use large O 3 concentrations, HO 2 can then be converted to OH by O 3 , giving rise to a higher yield of OH than observed in this study, using low O 3 concentrations (Atkinson et al 2004; Jenkin 2004).…”

Communication: Thermal unimolecular decomposition of syn-CH3CHOO: A kinetic study

“…[1][2][3][4][5][6] Hot CIs have sufficient internal energies to undergo prompt H-migration and/or ring-closure, leading to formations of OH radicals and/or organic acids/esters, respectively. 7 Cold CIs, in contrast, have insufficient internal energies to undergo fast unimolecular reactions, 7 and thus, their lifetimes are much longer than those of hot CIs. 7 Somewhat paradoxically, the direct observation of cold CH 2 OO resulting from the ozonolysis of ethylene was only reported very recently.…”

“…7 Cold CIs, in contrast, have insufficient internal energies to undergo fast unimolecular reactions, 7 and thus, their lifetimes are much longer than those of hot CIs. 7 Somewhat paradoxically, the direct observation of cold CH 2 OO resulting from the ozonolysis of ethylene was only reported very recently. 8 This finding indicates that stabilized Criegee intermediates (SCIs) rapidly react with other species (such as H 2 O, CH 2 O, or other CIs), which are present.…”

“…8 This finding indicates that stabilized Criegee intermediates (SCIs) rapidly react with other species (such as H 2 O, CH 2 O, or other CIs), which are present. 7 Because SCIs are readily consumed, they have very low steady-state concentrations, 8 and consequently their fate in the atmosphere is not well established. 1 To provide a relatively clean source of SCIs for spectroscopic, 9-21 dynamics, [22][23][24][25][26] and kinetics studies, [27][28][29][30][31][32][33][34][35][36] SCIs are almost exclusively made from photo-oxidation reactions of (R 1 R 2 )CI 2 in the presence of O 2 (where R 1 /R 2 represent hydrogen atoms or alkyl radicals To provide accurate rate constants and to aid experimental measurements, unimolecular decomposition rate constants of syn-CH 3 CHOO under atmospheric conditions are computed here from first principles using Miller's semiclassical transition state theory (SCTST) [41][42][43][44][45] in combination with a two-dimensional master equation (2DME) approach.…”

“…1 To provide a relatively clean source of SCIs for spectroscopic, 9-21 dynamics, [22][23][24][25][26] and kinetics studies, [27][28][29][30][31][32][33][34][35][36] SCIs are almost exclusively made from photo-oxidation reactions of (R 1 R 2 )CI 2 in the presence of O 2 (where R 1 /R 2 represent hydrogen atoms or alkyl radicals To provide accurate rate constants and to aid experimental measurements, unimolecular decomposition rate constants of syn-CH 3 CHOO under atmospheric conditions are computed here from first principles using Miller's semiclassical transition state theory (SCTST) [41][42][43][44][45] in combination with a two-dimensional master equation (2DME) approach. 7,46 This chemical kinetics analysis is performed using a high accuracy potential energy surface that is constructed with a modification of the HEAT protocol. [47][48][49] In addition, we investigate the fate of vinyl hydrogen peroxide (VHP), which was recently detected as an intermediate in a carboxylic acid-catalyzed tautomerization study of syn-CH 3 CHOO.…”