Reaction of Stabilized Criegee Intermediates from Ozonolysis of Limonene with Sulfur Dioxide: Ab Initio and DFT Study

Abstract

The mechanism of the reaction of the sulfur dioxide (SO(2)) with four stabilized Criegee intermediates (stabCI-CH(3)-OO, stabCI-OO, stabCIx-OO, and stabCH(2)OO) produced via the ozonolysis of limonene have been investigated using ab initio and DFT (density functional theory) methods. It has been shown that the intermediate adduct formed by the initiation of these reactions may be followed by two different reaction pathways such as H migration reaction to form carboxylic acids and rearrangement of oxygen to produce the sulfur trioxide (SO(3)) from the terminal oxygen of the COO group and SO(2). We found that the reaction of stabCI-OO and stabCH(2)OO with SO(2) can occur via both the aforementioned scenarios, whereas that of stabCI-CH(3)-OO and stabCIx-OO with SO(2) is limited to the second pathway only due to the absence of migrating H atoms. It has been shown that at the CCSD(T)/6-31G(d) + CF level of theory the activation energies of six reaction pathways are in the range of 14.18-22.59 kcal mol(-1), with the reaction between stabCIx-OO and SO(2) as the most favorable pathway of 14.18 kcal mol(-1) activation energy and that the reaction of stabCI-OO and stabCH(2)OO with SO(2) occurs mainly via the second reaction path. The thermochemical analysis of the reaction between SO(2) and stabilized Criegee intermediates indicates that the reaction of SO(2) and stabilized Criegee intermediates formed from the exocyclic primary ozonide decomposition is the main pathway of the SO(3) formation. This is likely to explain the large (~100%) difference in the production rate in the favor of the exocyclic compounds observed in recent experiments on the formation of H(2)SO(4) from exocyclic and endocyclic compounds.

A new atmospherically relevant oxidant of sulphur dioxide

“…20,23 , as well as laboratory experiments 24 , have found the SO 2 1 sCI reaction to be significantly faster than previously thought. Another property that influences the oxidation capacity of sCIs is their lifetime against unimolecular decomposition reactions.…”

Estimating the atmospheric concentration of Criegee intermediates and their possible interference in a FAGE-LIF instrument

“…Some of these studies focused in particular on the possible impact that SCIs might have on the formation of sulfuric acid (H 2 SO 4 ) in the gas phase, following Mauldin III et al (2012), who suggested that Criegee intermediates are the missing SO 2 oxidant needed to close the sulfuric acid budget over a boreal forest. This is supported by theoretical and laboratory studies that have determined a rate coefficient between SCIs and sulfur dioxide (SO 2 ) of the order of 10 −11 cm 3 molecule −1 s −1 (Aplincourt and Ruiz-López, 2000;Jiang et al, 2010;Kurteìn et al, 2011;Vereecken et al, 2012;Welz et al, 2012;Liu et al, 2014b;Sheps et al, 2014;Stone et al, 2014). As the main atmospherically relevant oxidiser of SO 2 in the gas phase is the OH radical with a rather slow rate coefficient at ambient temperature and pressure of 2 × 10 −12 cm 3 molecule −1 s −1 (Atkinson et al, 2004), the high rate coefficient for SO 2 oxidation would allow SCIs to have a significant impact on the H 2 SO 4 formation even if present in small concentrations.…”

Formation of secondary organic aerosols from the ozonolysis of dihydrofurans

“…Previous theoretical studies have shown that the first step of the sCI with SO 2 is the formation of a cyclic secondary ozonide (SOZ) that can undergo decomposition to the corresponding carbonyl and SO 3 or isomerisation involving a 1,2-H-shift leading to an organic acid and SO 2 (Jiang et al, 2010;Kurten et al, 2011). The release of SO 3 would produce H 2 SO 4 in the presence of water molecules.…”