Multiphase Chemistry of Glyoxal: Revised Kinetics of the Alkyl Radical Reaction with Molecular Oxygen and the Reaction of Glyoxal with OH, NO₃, and SO₄^– in Aqueous Solution

Abstract

The rate constant for the reaction of the hydrated glyoxyl radical (CH(OH)2-C(OH)2(·) with O2 has been determined as k(298) K = (1.2 ± 0.3) × 10(9) L mol(-1) s(-1) at pH 4.8. This experimental value is considerably higher than a widely used estimated value of about k = 1 × 10(6) L mol(-1) s(-1). As the aqueous phase conversion of glyoxal is of wide interest for aqSOA formation, we suggest that the newly determined rate constant should be applied in multiphase models. The formation of the dimerization product tartaric acid has as well been studied. This product is found, however in significant yields only when the oxygen content of the solution is reduced. The formation of dimers from the recombination of alkyl radicals in the atmospheric aqueous phase should hence be treated with great care. Finally, the reactions of the free radicals OH, NO3, and SO4(-) with glyoxal have been investigated and rate constants of k(298) K (OH) = (9.2 ± 0.5) × 10(8) L mol(-1) s(-1), k(298) K (SO4(-)) = (2.4 ± 0.2) × 10(7) L mol(-1) s(-1) and k(298) K (NO3) = (4.5 ± 0.3) × 10(6) L mol(-1) s(-1) were obtained.

A quantification method for heat-decomposable methylglyoxal oligomers and its application on 1,3,5-trimethylbenzene SOA

“…Reference (Matrix-assisted) laser desorption/ionisation mass Dommen et al (2006); Kalberer et al (2004Kalberer et al ( , 2006; Reinhardt spectrometry (MALDI-MS, LDI-MS) et al (2007); Holmes and Petrucci (2006); Surratt et al (2006); Denkenberger et al (2007) etal/hemiacetal formation (Kalberer et al, 2004;Yasmeen et al, 2010), esterification (Altieri et al, 2008;Sato et al, 2012;De Haan et al, 2011;Sedehi et al, 2013), imine formation (Altieri et al, 2008;Sato et al, 2012;De Haan et al, 2011;Sedehi et al, 2013), hydrolysis of epoxides (Paulot et al, 2009;Surratt et al, 2010), polymerisation, and radical-radical reactions (Schaefer et al, 2015;Tan et al, 2012;Lim et al, 2013).…”

“…Radical-radical reactions are also postulated as a possible reaction pathway to form oligomers (Schaefer et al, 2015;Lim et al, 2010Lim et al, , 2013Rincon et al, 2009;Sun et al, 2010). Radical-radical reactions of methylglyoxal might occur following the H-atom abstraction of methylglyoxal with OH radicals and a subsequent recombination of the resulting alkyl radicals (as discussed for glyoxal in Schaefer et al, 2015).…”

“…Radical-radical reactions of methylglyoxal might occur following the H-atom abstraction of methylglyoxal with OH radicals and a subsequent recombination of the resulting alkyl radicals (as discussed for glyoxal in Schaefer et al, 2015). The contribution of radical-radical reactions to oligomer formation is not well understood as the reaction of alkyl radicals with oxygen clearly tends to suppress this pathway.…”

ToF‐SIMS characterization of glyoxal surface oxidation products by hydrogen peroxide: A comparison between dry and liquid samples

“…Glyoxal, a ubiquitous organic compound, is emitted from a wide variety of anthropogenic and natural sources. It has attracted much attention because of its importance in aqSOA formation . In the atmosphere, hydrogen peroxide (H 2 O 2 ) is a main source of hydroxyl radicals (•OH, abbreviated as OH in the following) under UV irradiation, and the reaction of OH radicals with glyoxal leads to SOA formation .…”

Technical note: Updated parameterization of the reactive uptake of glyoxal and methylglyoxal by atmospheric aerosols and cloud droplets

“…For cloud droplets, KH, w is used due to the low ion concentrations in cloudwater (Ervens, 2015;McNeill, 2015 (Schaefer et al, 2015) b (Schaefer et al, 2012) c (Betterton and Hoffmann, 1988) d (Kampf et al, 2013) 20 e (Waxman et al, 2015) Statistical analysis and parameter estimation. The calculated reactive uptake coefficient, , for MGLY and GLYX and each particle type was parameterized as a function of relative humidity via weighted least squares regression.…”