Identification of the acetaldehyde oxide Criegee intermediate reaction network in the ozone-assisted low-temperature oxidation of trans-2-butene. Issue 41 (15th October 2021)

• Record Type: Journal Article
• Authors: Conrad, Alan R.; Hansen, Nils; Jasper, Ahren W.; Thomason, Natasha K.; Hidaldo-Rodrigues, Laura; Treshock, Sean P.; Popolan-Vaida, Denisia M.
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 41(2021)
• Page Start: 23554
• Page End: 23566
• Publication Date: 2021-10-15
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp03126k
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Jet stirred reactor investigation of ozone-assisted low-temperature oxidation of trans -2-butene reveals an acetaldehyde oxide Criegee intermediate reaction network. Abstract : Uni- and bi-molecular reactions involving Criegee intermediates (CIs) have been the focus of many studies due to the role these molecules play in atmospheric chemistry. The reactivity of CIs is known to strongly depend on their structure. The reaction network of the second simplest CI, acetaldehyde oxide (CH3 CHOO), is investigated in this work in an atmospheric pressure jet-stirred reactor (JSR) during the ozonolysis of trans -2-butene to explore the kinetic pathways relevant to atmospheric chemistry and low-temperature combustion. The mole fraction profiles of reactants, intermediates, and final products are determined by means of molecular-beam mass spectrometry in conjunction with single-photon ionization employing tunable synchrotron-generated vacuum ultraviolet radiation. A network of CI reactions is identified in the temperature region below 600 K, characterized by CI addition to trans -2-butene, water, formaldehyde, formic acid, and methanol. No sequential additions of the CH3 CHOO CI are observed, in contrast with the reactivity of the simplest CI (H2 COO) and the earlier observation of an extensive reaction network with up to four H2 COO sequential additions ( Phys. Chem. Chem. Phys., 2019, 21, 7341–7357). Experimental photoionization efficiency scans recorded at 300 K and 425 K and ab initio threshold energy calculations lead to the identification and quantification of previously elusive intermediates, such as ketohydroperoxide and hydroperoxide species. Specifically, the C4 H8 + O3 adduct is identified as a ketohydroperoxide (KHP, 3-hydroperoxybutan-2-one, CH3 C(O)CH(CH3 )OOH), while hydroxyacetaldehyde (glycolaldehyde, HCOCH2 OH) formation is attributed to unimolecular isomerization of the CIs. Other hydroperoxide species such as methyl hydroperoxide (CH3 OOH), ethyl hydroperoxide (C2 H5 OOH), butyl hydroperoxide (OOH), hydroperoxyl acetaldehyde (HOOCH2 CHO), hydroxyethyl hydroperoxide (CH3 CH(OH)OOH), but-1-enyl-3-hydroperoxide, and 4-hydroxy-3-methylpentan-2-one (HOCH(CH3 )CH(CH3 )C(O)CH3 ) are also identified. Detection of additional oxygenated species such as methanol, ethanol, ketene, and aldehydes suggests multiple active oxidation routes. These results provide additional evidence that CIs are key intermediates of the ozone-unsaturated hydrocarbon reactions providing critical inputs for improved kinetics models.