Thermal Desorption Mass Spectrometric Analysis of Organic Aerosol Formed from Reactions of 1-Tetradecene and O₃ in the Presence of Alcohols and Carboxylic Acids

Abstract

The chemistry of secondary organic aerosol formation from reactions of 1-tetradecene and O3 in dry air in the presence of excess alcohols and carboxylic acids was investigated in an environmental chamber using a thermal desorption particle beam mass spectrometer. Temperature-programmed thermal desorption of collected aerosol shows that in each reaction two major aerosol products are formed. The more volatile compounds in each pair of products are α-alkoxytridecyl or α-acyloxytridecyl hydroperoxides, which were identified by comparison of mass spectra with those of standard compounds generated by the corresponding liquid-phase ozonolysis reactions. The formation of organic hydroperoxides in the gas and liquid phases is consistent with a mechanism involving reactions of the alcohols and carboxylic acids with stabilized Criegee biradicals generated in the alkene−O3 reaction. The less volatile compounds are α-alkoxy-α‘-hydroxyditridecyl or α-acyloxy-α‘-hydroxyditridecyl peroxides (peroxyhemiacetals) formed by reactions of the hydroperoxides with tridecanal, which is generated along with formaldehyde during biradical formation. The vapor pressures of these compounds estimated from their desorption temperatures are ∼10-7−10-14 Torr. These types of reactions could play a role in atmospheric aerosol nucleation and growth and provide a mechanism for creating fine-particle organic peroxides, which are currently of interest because of their potential for adversely impacting human health.

Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

“…During the first several hours, the particle phase is dominated by first-to third-generation SVOCs, which are progressively converted to higher generation SVOCs in the gas phase and low volatility products in the particle phase. The contribution of particle-phase products to the total SOA budget is predicted to exceed 60% after ∼5 h. The dominance of low-volatility particle-phase products is consistent with previous studies, in which peroxyhemiacetals were found to be major products in SOA derived from oxidation of alkenes (1-tetradecene) (23,24), aromatic hydrocarbons (toluene) (25,26), and monoterpenes (α-and β-pinene) (27). Fig.…”

“…1C). The particle-phase reactions are predicted to occur mainly at and near the surface, consistent with a product analysis study suggesting that PHA formation should occur mainly at the particle surface (24). Fig.…”

Role of the reaction of stabilized Criegee intermediates with peroxy radicals in particle formation and growth in air

“…Accurate mass measurements (Table 2) of selected OLI-D oligomers agree well with the expected elemental composition for these peroxyhemiacetals. Formation of peroxyhemiacetals has also been suggested in SOA from ozonolysis of 1-tetradecene, 69 a-pinene, 16,23 and ethylene, 44 and photooxidation of dodecane 70 and toluene. 71 Fig .…”

Identification of Organic Hydroperoxides and Peroxy Acids Using Atmospheric Pressure Chemical Ionization – Tandem Mass Spectrometry (APCI-MS/MS): Application to Secondary Organic Aerosol

“…Several mechanisms for oligomer product formation in SOA arising from VOC oxidation have been proposed: i) self-and cross-reactions of the peroxy radicals (RO 2 ) (Zhang et al, 2016), ii) reaction of ozonolysis products in the condensed-phase, such as aldol condensation, esterification, hemiacetal and peroxyhemiacetal formation (Ziemann, 2003;Tolocka et al, 2004;Kristensen et al, 2014;Docherty et al, 2005;Muller et al, 2009;Yasmeen et al, 2010;Hall and Johnston, 2012;Witkowski and Gierczak, 2012;DePalma et al, 2013;Lim and Turpin, 2015), iii) dimer cluster formation from carboxylic acids 15 (Hoffmann et al, 1998;Tobias and Ziemann, 2000;Claeys et al, 2009;Camredon et al, 2010;DePalma et al, 2013), iv) reactions of Criegee intermediates (CIs) with VOCs oxidation products (Bonn et al, 2002;Lee and Kamens, 2005;Tolocka et al, 2006;Heaton et al, 2007;Witkowski and Gierczak, 2012;Kristensen et al, 2016;Wang et al, 2016), and vi) reactions of RO 2 radicals with Cis (Sadezky et al, 2008;Zhao et al, 2015). Among them, the reactions of CIs with protic substances (water, alcohols, acids and hydroperoxides) can form ROOH.…”