Mass spectrometry distinguishing C=C location and cis/trans isomers: A strategy initiated by water radical cations

Zhang, Xiaoping; Ren, Xiang; Chingin, Konstantin; Xu, Jiaquan; Yan, Xingru; Chen, Huanwen

doi:10.1016/j.aca.2020.09.027

Cited by 26 publications

(30 citation statements)

References 40 publications

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“…Figure a shows a typical mass spectrum generated through the +5.5 kV corona discharge of water vapor in argon before introducing benzene vapor into the reagent spray-channel (Figure S1; experimental details in Supporting Information). The signal of water dimer radical cations (H 2 O) 2 +• ( m / z 36) along with protonated water clusters were clearly detected, which is consistent with the previous report Figure b shows a mass spectrum generated after benzene vapor was introduced into the reagent spray-channel at about 1.6 min.…”

Section: Results and Discussionsupporting

confidence: 91%

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Generation of Phenol and Molecular Hydrogen through Catalyst-Free C–H Activation of Benzene by Water Radical Cations

Mao

Wei

et al. 2021

J. Am. Soc. Mass Spectrom.

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Here, we report on the abundant formation of phenol and molecular hydrogen when benzene vapor was exposed to gas plasma generated by +5.5 kV corona discharge of water vapor in argon in the absence of oxygen. Systematic analysis using a series of isotopic standards (d 6-benzene, D2O, and H2 18O) and benzene derivatives (mono-, di-, trichlorobenzene, and N,N-dimethylaniline) indicated that the formation of phenol occurred through the reaction between neutral benzene and the radical cation of water dimer, (H2O)2 +•. A two-step reaction mechanism was proposed based on the results of experiments and DFT calculations: (1) the formation of (C6H6...H2O)+• intermediate through electrophilic addition; (2) the formation of C6H5OH+• through the release of H2 from the (C6H6...H2O)+• intermediate. Our findings offer a novel catalyst-free method to prepare phenol from benzene with phenol selectivity >90%.

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Section: Results and Discussionsupporting

confidence: 91%

“…The MS instrument was coupled with a home-built low-energy ambient corona discharge device with two channels for ion generation. Details of the ionization source are given in previous reports from our laboratory. − …”

Section: Methodsmentioning

confidence: 99%

Generation of Phenol and Molecular Hydrogen through Catalyst-Free C–H Activation of Benzene by Water Radical Cations

Mao

Wei

et al. 2021

J. Am. Soc. Mass Spectrom.

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“…It is known that the water radical cation forms as an O-O weakly bonded dimer (i.e., [H 2 O∙∙∙OH 2 ] + ˙) and that this species can react with various unsaturated compounds to form water radical cation adducts. Examples include alkenes ( Zhang et al, 2020 ), benzene ( Mi et al, 2022 ), acetone ( Zhang X. et al, 2021 ), ethyl acetate ( Wang et al, 2021 ) and various sulfones ( Qiu et al, 2022 ). The variety of substrates that form adducts with the water radical cation and the spontaneous oxidation driven as a result of adduct formation, triggered our interest in systematically exploring the properties of water radical cation adducts generated in microdroplets.…”

Section: Resultsmentioning

confidence: 99%

Spontaneous Water Radical Cation Oxidation at Double Bonds in Microdroplets

et al. 2022

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Spontaneous oxidation of compounds containing diverse X=Y moieties (e.g., sulfonamides, ketones, esters, sulfones) occurs readily in organic-solvent microdroplets. This surprising phenomenon is proposed to be driven by the generation of an intermediate species [M+H2O]+·: a covalent adduct of water radical cation (H2O+·) with the reactant molecule (M). The adduct is observed in the positive ion mass spectrum while its formation in the interfacial region of the microdroplet (i.e., at the air-droplet interface) is indicated by the strong dependence of the oxidation product formation on the spray distance (which reflects the droplet size and consequently the surface-to-volume ratio) and the solvent composition. Importantly, based on the screening of a ca. 21,000-compound library and the detailed consideration of six functional groups, the formation of a molecular adduct with the water radical cation is a significant route to ionization in positive ion mode electrospray, where it is favored in those compounds with X=Y moieties which lack basic groups. A set of model monofunctional systems was studied and in one case, benzyl benzoate, evidence was found for oxidation driven by hydroxyl radical adduct formation followed by protonation in addition to the dominant water radical cation addition process. Significant implications of molecular ionization by water radical cations for oxidation processes in atmospheric aerosols, analytical mass spectrometry and small-scale synthesis are noted.

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“…26 New methods have been developed to distinguish lipids at this very high degree of chemical detail. 27–29 Without seeking to utilize this extra dimension of information, we demonstrate the potential to solve the larger problem by showing direct analysis by DESI using a repetition time of under 10 seconds to acquire the full 2D MS/MS data domain.…”

Section: Introductionmentioning

confidence: 99%