Isomeric hexyl‐ketohydroperoxides formed by reactions of hexoxy and hexylperoxy radicals in oxygen

Jorand, F.; Heiss, Adolphe; Perrin, Olivier; Sahetchian, Krikor; Kerhoas, Lucien; Einhorn, Jacques

doi:10.1002/kin.10136

Cited by 28 publications

(24 citation statements)

References 36 publications

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“…Further, it was suggested that a radical chain of peroxy radical formation and intramolecular H shifts could be the path to ELVOC formation, resulting in multiple hydroperoxides with increasing oxygen content in steps of 32 Da . H migration to peroxy radicals is known at elevated temperatures and for specific atmospheric radicals (Cox and Cole, 1985;Glowacki and Pilling, 2010;Jorand et al, 2003;Perrin et al, 1998) and the mechanism is commensurable with recent findings for the autoxidation of isoprene and related compounds (Crounse et al, 2012(Crounse et al, , 2013(Crounse et al, , 2011Praplan et al, 2012) and with quantum-mechanical calculations, regarding the oxidation of monoterpenes (Vereecken and Francisco, 2012;Nguyen et al, 2010;Peeters et al, 2009;Vereecken et al, 2007). Jokinen et al (2014) demonstrated HOM formation in detail for limonene, a monoterpene.…”

Section: T F Mentel Et Al: Formation Of Highly Oxidized Multifunctsupporting

confidence: 72%

“…We will also allow for H shifts from C-H bonds also in peroxy radicals (Sequence 4), leading to -OOH functionalized peroxy radicals (Crounse et al, 2013;Vereecken et al, 2007). This rearrangement was known for processes at elevated temperatures (Cox and Cole, 1985;Glowacki and Pilling, 2010;Jorand et al, 2003;Perrin et al, 1998), but has not been considered as important in gas-phase atmospheric chemistry until recently. In addition, intramolecular termination R9c can occur, an H shift from the C-H bond that carries the hydroperoxy group, leading to a split off of OH and a carbonyl termination product (Crounse et al, 2013;.…”

Section: Methodsmentioning

confidence: 99%

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Formation of highly oxidized multifunctional compounds: autoxidation of peroxy radicals formed in the ozonolysis of alkenes – deduced from structure–product relationships

Mentel¹,

Springer²,

et al. 2015

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Abstract. It has been postulated that secondary organic particulate matter plays a pivotal role in the early growth of newly formed particles in forest areas. The recently detected class of extremely low volatile organic compounds (ELVOC) provides the missing organic vapors and possibly contributes a significant fraction to atmospheric SOA (secondary organic aerosol). The sequential rearrangement of peroxy radicals and subsequent O 2 addition results in ELVOC which are highly oxidized multifunctional molecules (HOM). Key for efficiency of such HOM in early particle growth is that their formation is induced by one attack of the oxidant (here O 3 ), followed by an autoxidation process involving molecular oxygen. Similar mechanisms were recently observed and predicted by quantum mechanical calculations e.g., for isoprene. To assess the atmospheric importance and therewith the potential generality, it is crucial to understand the formation pathway of HOM.To elucidate the formation path of HOM as well as necessary and sufficient structural prerequisites of their formation we studied homologous series of cycloalkenes in comparison to two monoterpenes. We were able to directly observe highly oxidized multifunctional peroxy radicals with 8 or 10 O atoms by an Atmospheric Pressure interface High Resolution Time of Flight Mass Spectrometer (APi-TOF-MS) equipped with a NO − 3 -chemical ionization (CI) source. In the case of O 3 acting as an oxidant, the starting peroxy radical is formed on the so-called vinylhydroperoxide path. HOM peroxy radicals and their termination reactions with other peroxy radicals, including dimerization, allowed for analyzing the observed mass spectra and narrowing down the likely formation path. As consequence, we propose that HOM are multifunctional percarboxylic acids, with carbonyl, hydroperoxy, or hydroxy groups arising from the termination steps. We figured that aldehyde groups facilitate the initial rearrangement steps. In simple molecules like cycloalkenes, autoxidation was limited to both terminal C atoms and two further C atoms in the respective α positions. In more complex molecules containing tertiary H atoms or small, constrained rings, even higher oxidation degrees were possible, either by simple H shift of the tertiary H atom or by initialization of complex ring-opening reactions.

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Section: T F Mentel Et Al: Formation Of Highly Oxidized Multifunctsupporting

confidence: 72%

Section: Methodsmentioning

confidence: 99%

Formation of highly oxidized multifunctional compounds: autoxidation of peroxy radicals formed in the ozonolysis of alkenes – deduced from structure–product relationships

Mentel¹,

Springer²,

et al. 2015

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“…The existence of an autoxidation pathway in this system has previously been demonstrated at elevated temperature (5). In the atmosphere, oxidation of hexane by the hydroxyl radical (OH) in the presence of NO produces alkoxy radicals, an example of which is shown in Scheme 1.…”

mentioning

confidence: 74%

Atmospheric autoxidation is increasingly important in urban and suburban North America

Praske

Otkjær

Crounse

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

183

310

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Gas-phase autoxidation-regenerative peroxy radical formation following intramolecular hydrogen shifts-is known to be important in the combustion of organic materials. The relevance of this chemistry in the oxidation of organics in the atmosphere has received less attention due, in part, to the lack of kinetic data at relevant temperatures. Here, we combine computational and experimental approaches to investigate the rate of autoxidation for organic peroxy radicals (RO 2 ) produced in the oxidation of a prototypical atmospheric pollutant, n-hexane. We find that the reaction rate depends critically on the molecular configuration of the RO 2 radical undergoing hydrogen transfer (H-shift). RO 2 H-shift rate coefficients via transition states involving six-and seven-membered rings (1,5 and 1,6 H-shifts, respectively) of α-OH hydrogens (HOC-H) formed in this system are of order 0.1 s −1 at 296 K, while the 1,4 H-shift is calculated to be orders of magnitude slower. Consistent with H-shift reactions over a substantial energetic barrier, we find that the rate coefficients of these reactions increase rapidly with temperature and exhibit a large, primary, kinetic isotope effect. The observed H-shift rate coefficients are sufficiently fast that, as a result of ongoing NO x emission reductions, autoxidation is now competing with bimolecular chemistry even in the most polluted North American cities, particularly during summer afternoons when NO levels are low and temperatures are elevated.atmospheric chemistry | air pollution | autoxidation

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“…It should also be noted that the lifetime of the RO 2 radicals with respect to reactions with HO 2 and the RO 2 pool can be very long under atmospheric conditions (i.e., minutes). It is therefore possible that unimolecular rearrangements (e.g., Jorand et al, 2003) or heterogeneous aerosol reactions (Bonn et al, 2007) may also play a role for some peroxy radical classes.…”

Section: Generation Of Atmospheric Degradation Mechanisms For Vocsmentioning

confidence: 99%

The formation, properties and impact of secondary organic aerosol: current and emerging issues

et al. 2009

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Abstract. Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol and a detailed knowledge of the formation, properties and transformation of SOA is therefore required to evaluate its impact on atmospheric processes, climate and human health. The chemical and physical processes associated with SOA formation are complex and varied, and, despite considerable progress in recent years, a quantitative and predictive understanding of SOA formation does not exist and therefore represents a major research challenge in atmospheric science. This review begins with an update on the current state of knowledge on the global SOA budget and is followed by an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and the analytical techniques used to determine the chemical composition of SOA. A survey of recent laboratory, field and modeling studies is also presented. The following topical and emerging issues are highlighted and discussed in detail: molecular characterization of biogenic SOA constituents, condensed phase reactions and oligomerization, the interaction of atmospheric organic components with sulfuric acid, the chemical and photochemical processing of organics in the atmospheric aqueous phase, aerosol formation from real plant emissions, interaction of atmospheric organic components with water, thermodynamics and mixtures in atmospheric models. Finally, the major challenges ahead in laboratory, field and modeling studies of SOA are discussed and recommendations for future research directions are proposed.

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Isomeric hexyl‐ketohydroperoxides formed by reactions of hexoxy and hexylperoxy radicals in oxygen

Cited by 28 publications

References 36 publications

Formation of highly oxidized multifunctional compounds: autoxidation of peroxy radicals formed in the ozonolysis of alkenes – deduced from structure–product relationships

Formation of highly oxidized multifunctional compounds: autoxidation of peroxy radicals formed in the ozonolysis of alkenes – deduced from structure–product relationships

Atmospheric autoxidation is increasingly important in urban and suburban North America

The formation, properties and impact of secondary organic aerosol: current and emerging issues

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