Ion-molecule reactions and thermal decomposition of ions in nitrogen-oxygen alkane (C2-C8) mixtures studied by time-resolved atmospheric pressure ionization mass spectrometry

Matsuoka, Shingo; Ikezoe, Yasumasa

doi:10.1021/j100316a025

Cited by 25 publications

(37 citation statements)

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“…Only for n-octane, among all hydrocarbons analyzed in this study, is such charge transfer not completely dissociative and the molecular ion, M ϩ• , is detected in the APCI spectra. This finding is consistent with the observation that in the reaction of linear hydrocarbons with O 2 ϩ• , longer carbon chains increase the stability of M ϩ• with regard to both hydrogen transfer to O 2 [17] and fragmentation to alkyl cations [19]. As for the formation of [M Ϫ H] ϩ , it was found that the two-step process shown in (a) is kinetically favored with respect to direct hydride transfer from M to O 2 ϩ• [17].…”

Section: Cyclohexanesupporting

confidence: 92%

“…This finding is consistent with the observation that in the reaction of linear hydrocarbons with O 2 ϩ• , longer carbon chains increase the stability of M ϩ• with regard to both hydrogen transfer to O 2 [17] and fragmentation to alkyl cations [19]. As for the formation of [M Ϫ H] ϩ , it was found that the two-step process shown in (a) is kinetically favored with respect to direct hydride transfer from M to O 2 ϩ• [17]. As for process (b), SIFT (selected ion flow tube) experiments [18,19,22] have shown that hydride abstraction by NO ϩ is exothermic for all hydrocarbons analyzed in the present study.…”

Section: Cyclohexanesupporting

confidence: 92%

“…V cone -induced fragmentation leads to the formation of C n H 2nϩ1 ϩ (n ϭ 3-6) ions at low energies, and of C n H 2nϩ1 ϩ (n ϭ 2) and C n H 2,Ϫ1 ϩ (n ϭ 2-3) ions at higher energies. At any given V cone value applied, more extensive fragmentation is observed at 300 than at 30°C, an effect that can be ascribed to thermal decomposition of the ions, as described in the literature [17,18,28]. In contrast with the linear hydrocarbons, the complex NO ϩ (M) (m/z 144) is observed at both 300 and 30°C, whereas the species C 4 H 7 ϩ (M) (m/z 169) is not detected at any temperature within the range explored ( Figure S4 in the Supplementary Material).…”

Section: 2-dimethylpentanementioning

confidence: 57%

“…All reactions proposed in Scheme 2 have precedents in the literature. With regard to process (a), it is known that the main reaction of O 2 ϩ• with alkanes is charge transfer, which occurs at collision rate, and, depending on the hydrocarbon, can be nondissociative and/or dissociative [17][18][19]. Specifically, charge transfer from O 2 ϩ• to M is energetically highly favorable for all hydrocarbons considered in this study (⌬H of reaction ranges from Ϫ172.7 to Ϫ219.0 kJ mol Ϫ1 for linear C 5 to C 8 hydrocarbons [37]) and is therefore a most likely route for the formation of alkyl fragment ions (R ϩ ).…”

Section: Cyclohexanementioning

confidence: 99%

“…It was found that O 2 ϩ• reacts mainly by dissociative or nondissociative charge transfer [17][18][19], NO ϩ by hydride abstraction [18 -22], and H 3 O ϩ by association [19,22]. Moreover, there are a few reports on the APCI-MS and ion mobility spectrometry (IMS) of alkanes, alkenes, and cycloalkanes in air [23,24].…”

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confidence: 99%

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A mass spectrometry study of alkanes in air plasma at atmospheric pressure

Marotta

Paradisi

2008

J. Am. Soc. Mass Spectrom.

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The positive APCI-mass spectra in air of linear (n-pentane, n-hexane, n-heptane, n-octane), branched [2,4-dimethylpentane, 2,2-dimethylpentane and 2,2,4-trimethylpentane (i-octane)], and cyclic (cyclohexane) alkanes were analyzed at different mixing ratios and temperatures. The effect of air humidity was also investigated. Complex ion chemistry is observed as a result of the interplay of several different reagent ions, including atmospheric ions O 2 ϩ• , NO ϩ , H 3 O ϩ , and their hydrates, but also alkyl fragment ions derived from the alkanes. Some of these reactions are known from previous selected ion/molecule reaction studies; others are so far unreported. The major ion formed from most alkanes (M) is the species [M Ϫ H] ϩ , which is accompanied by M ϩ• only in the case of n-octane. Ionic fragments of C n H 2nϩ1 ϩ composition are also observed, particularly with branched alkanes: the relative abundance of such fragments with respect to that of [M Ϫ H] ϩ decreases with increasing concentration of M, thus suggesting that they react with M via hydride abstraction. The branched C 7 and C 8 alkanes react with NO ϩ to form a C 4 H 10 NO ϩ ion product, which upon collisional activation dissociates via HNO elimination. The structure of t-Bu ϩ (HNO) is proposed for such species, which is reasonably formed from the original NO ϩ (M) ion/molecule complex via hydride transfer and olefin elimination. . For air pollution control, different types of reactors and power supplies are being developed and tested for production of nonthermal plasmas by means of electrical discharges [3]. Following an initial phase devoted to prove the feasibility and competitiveness of the process in terms of energy and cost efficiency, research is presently focusing on the characterization of the chemistry-i.e., the products being released and the underlying chemical mechanisms-to develop a more efficient and cleaner process [5].In nonthermal plasmas, which are conveniently produced by electric corona discharges in air at atmospheric pressure, high-energy electrons induce ionization, excitation, and dissociation of the bulk gas molecules, N 2 and O 2 . The resulting reactive species, ionic and neutral as well as thermalized electrons, can attack molecules of organic pollutants present in the air, such as hydrocarbons and other volatile organic compounds (VOCs), and initiate a chain of reactions leading eventually to their oxidation. It is generally accepted that nonthermal plasma-induced VOC oxidation proceeds via VOC-derived organic radicals, R • , which are trapped by molecular oxygen and undergo further reactions as described for their tropospheric oxidation [6], leading eventually to CO 2 . As for the origin of such VOC-derived radicals, i.e., the nature of the initiation steps of nonthermal plasma-induced VOC decay, reactions of VOC molecules with neutrals and radicals, notably O( 3 P) and • OH, are usually envisioned. However, increasing numbers of literature reports suggest that in some cases ionic initiation steps might prevail [7][8][9...

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Section: Cyclohexanesupporting

confidence: 92%

Section: Cyclohexanesupporting

confidence: 92%

Section: 2-dimethylpentanementioning

confidence: 57%

Section: Cyclohexanementioning

confidence: 99%

mentioning

confidence: 99%

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A mass spectrometry study of alkanes in air plasma at atmospheric pressure

Marotta

Paradisi

2008

J. Am. Soc. Mass Spectrom.

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Mass spectrometric monitoring of oxidation of aliphatic C6–C8 hydrocarbons and ethanol in low pressure oxygen and air plasmas

et al. 2016

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Experimental and theoretical studies on the oxidation of saturated hydrocarbons (n-hexane, cyclohexane, n-heptane, n-octane and isooctane) and ethanol in 28 Torr O or air plasma generated by a hollow cathode discharge ion source were made. Ions corresponding to [M + 15] and [M + 13] in addition to [M - H] and [M - 3H] were detected as major ions where M is the sample molecule. The ions [M + 15] and [M + 13] were assigned as oxidation products, [M - H + O] and [M - 3H + O] , respectively. By the tandem mass spectrometry analysis of [M - H + O] and [M - 3H + O] , H O, olefins (and/or cycloalkanes) and oxygen-containing compounds were eliminated from these ions. Ozone as one of the terminal products in the O plasma was postulated as the oxidizing reagent. As an example, the reactions of C H with O and of C H (CH CH CH CH CH CH ) with ozone were examined by density functional theory calculations. Nucleophilic interaction of ozone with C H leads to the formation of protonated ketone, CH CH C(=OH )CH CH CH . In air plasma, [M - H + O] became predominant over carbocations, [M - H] and [M - 3H] . For ethanol, the protonated acetic acid CH C(OH) (m/z 61.03) was formed as the oxidation product. The peaks at m/z 75.04 and 75.08 are assigned as protonated ethyl formate and protonated diethyl ether, respectively, and that at m/z 89.06 as protonated ethyl acetate. Copyright © 2016 John Wiley & Sons, Ltd.

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DC Corona Electric Discharges for Air Pollution Control, 2—Ionic Intermediates and Mechanisms of Hydrocarbon Processing

Marotta

Callea

Ren

et al. 2008

Plasma Processes & Polymers

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A mechanistic study is reported on i‐octane and hexane processing with +DC and −DC corona in air at room temperature and pressure. Current/voltage profiles are matched with the ion analysis data obtained by APCI mass spectrometry. With a −DC corona, the hydrocarbons do not modify the negative ion population with respect to uncontaminated air. In contrast, with a +DC corona many hydrocarbon‐derived positive ions form. O(3P) and •OH were also investigated using chemical probes (ozone formation and CO oxidation, respectively). The results, combined with efficiency and product data, suggest that with −DC corona radical initiation steps occur, whereas with +DC corona ionic reactions prevail.

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Ion-molecule reactions and thermal decomposition of ions in nitrogen-oxygen alkane (C2-C8) mixtures studied by time-resolved atmospheric pressure ionization mass spectrometry

Cited by 25 publications

References 0 publications

A mass spectrometry study of alkanes in air plasma at atmospheric pressure

A mass spectrometry study of alkanes in air plasma at atmospheric pressure

Mass spectrometric monitoring of oxidation of aliphatic C6–C8 hydrocarbons and ethanol in low pressure oxygen and air plasmas

DC Corona Electric Discharges for Air Pollution Control, 2—Ionic Intermediates and Mechanisms of Hydrocarbon Processing

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