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Ieritano C, Thomas P, Hopkins WS. Argentination: A Silver Bullet for Cannabinoid Separation by Differential Mobility Spectrometry. Anal Chem 2023. [PMID: 37224077 DOI: 10.1021/acs.analchem.3c01241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
As the legality of cannabis continues to evolve globally, there is a growing demand for methods that can accurately quantitate cannabinoids found in commercial products. However, the isobaric nature of many cannabinoids, along with variations in extraction methods and product formulations, makes cannabinoid quantitation by mass spectrometry (MS) challenging. Here, we demonstrate that differential mobility spectrometry (DMS) and tandem-MS can distinguish a set of seven cannabinoids, five of which are isobaric: Δ9-tetrahydrocannabinol (Δ9-THC), Δ8-THC, exo-THC, cannabidiol, cannabichromene, cannabinol, and cannabigerol. Analytes were detected as argentinated species ([M + Ag]+), which, when subjected to collision-induced dissociation, led to the unexpected discovery that argentination promotes distinct fragmentation patterns for each cannabinoid. The unique fragment ions formed were rationalized by discerning fragmentation mechanisms that follow each cannabinoid's MS3 behavior. The differing fragmentation behaviors between species suggest that argentination can distinguish cannabinoids by tandem-MS, although not quantitatively as some cannabinoids produce small amounts of a fragment ion that is isobaric with the major fragment generated by another cannabinoid. By adding DMS to the tandem-MS workflow, it becomes possible to resolve each cannabinoid in a pure N2 environment by deconvoluting the contribution of each cannabinoid to a specific fragmentation channel. To this end, we used DMS in conjunction with a multiple reaction monitoring workflow to assess cannabinoid levels in two cannabis extracts. Our methodology exhibited excellent accuracy, limits of detection (10-20 ppb depending on the cannabinoid), and linearity during quantitation by standard addition (R2 > 0.99).
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Affiliation(s)
- Christian Ieritano
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
- Waterloo Institute for Nanotechnology, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
- Watermine Innovation, Waterloo, Ontario N0B 2T0, Canada
| | - Patrick Thomas
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
- Waterloo Institute for Nanotechnology, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
- Watermine Innovation, Waterloo, Ontario N0B 2T0, Canada
- Centre for Eye and Vision Research, 17W Hong Kong Science Park, New Territories 999077, Hong Kong
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2
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More SA, Kardile RD, Kuo TC, Cheng MJ, Liu RS. Gold Catalysts Can Generate Nitrone Intermediates from a Nitrosoarene/Alkene Mixture, Enabling Two Distinct Catalytic Reactions: A Nitroso-Activated Cycloheptatriene/Benzylidene Rearrangement. Org Lett 2021; 23:5506-5511. [PMID: 34232666 DOI: 10.1021/acs.orglett.1c01857] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gold-catalyzed reactions of cycloheptatrienes with nitrosoarenes yield nitrone derivatives efficiently. This reaction sequence enables us to develop gold-catalyzed aerobic oxidations of cycloheptatrienes to afford benzaldehyde derivatives using CuCl and nitrosoarenes as co-catalysts (10-30 mol %). Our density functional theory calculations support a novel nitroso-activated rearrangement, tropylium → benzylidene. With the same nitrosoarenes, we developed their gold-catalyzed [2 + 2 + 1]-annulations between nitrosobenzene and two enol ethers to yield 5-alkoxyisoxazolidines using 1,4-cyclohexadienes as hydrogen donors.
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Affiliation(s)
- Sayaji Arjun More
- Frontier Research Center of Matter Science and Technology, Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China
| | - Rahul Dadabhau Kardile
- Frontier Research Center of Matter Science and Technology, Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China
| | - Tung-Chun Kuo
- Department of Chemistry, National Cheng Kung University, Tainan 70101, Taiwan, Republic of China
| | - Mu-Jeng Cheng
- Department of Chemistry, National Cheng Kung University, Tainan 70101, Taiwan, Republic of China
| | - Rai-Shung Liu
- Frontier Research Center of Matter Science and Technology, Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China
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Noble JA, Marceca E, Dedonder C, Phasayavan W, Féraud G, Inceesungvorn B, Jouvet C. Influence of the N atom position on the excited state photodynamics of protonated azaindole. Phys Chem Chem Phys 2020; 22:27280-27289. [PMID: 33227118 DOI: 10.1039/d0cp03608k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We present a study of the photofragmentation of three protonated azaindole molecules - 7-azaindole, 6-azaindole, and 5-azaindole - consisting of fused pyrrole-pyridine bicyclic aromatic systems, in which the pyridinic (protonated) nitrogen heteroatom is located at the 7, 6, and 5 positions, respectively. Photofragmentation electronic spectra of the isolated aforementioned azaindolinium cations reveal that their photodynamics extends over timescales covering nine orders of magnitude and provide evidence about the resultant fragmentation pathways. Moreover, we show how the position of the heteroatom in the aromatic skeleton influences the excited state energetics, fragmentation pathways, and fragmentation timescales. Computed ab initio adiabatic transition energies are used to assist the assignation of the spectra, while geometry optimisation in the excited electronic states as well as ab initio calculations along the potential surfaces demonstrate the role of ππ*/πσ* coupling and/or large geometry changes in the dynamics of these species. Evidence supporting the formation of Dewar valence isomers as intermediates involved in sub-picosecond relaxation processes is discussed.
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Affiliation(s)
- Jennifer A Noble
- CNRS, Aix Marseille Univ., PIIM, Physique des Interactions Ioniques et Moléculaires, UMR 7345, 13397, Marseille, France.
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Tyler Davidson J, Piacentino EL, Sasiene ZJ, Abiedalla Y, DeRuiter J, Clark CR, Berden G, Oomens J, Ryzhov V, Jackson GP. Identification of novel fragmentation pathways and fragment ion structures in the tandem mass spectra of protonated synthetic cathinones. Forensic Chem 2020. [DOI: 10.1016/j.forc.2020.100245] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Torma KG, Voronova K, Sztáray B, Bodi A. Dissociative Photoionization of the C7H8 Isomers Cycloheptatriene and Toluene: Looking at Two Sides of the Same Coin Simultaneously. J Phys Chem A 2019; 123:3454-3463. [DOI: 10.1021/acs.jpca.9b00936] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Krisztián G. Torma
- Department of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Krisztina Voronova
- Department of Chemistry, University of Nevada, Reno, Reno, Nevada 89557, United States
| | - Bálint Sztáray
- Department of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen PSI CH-5232, Switzerland
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Jusko P, Simon A, Banhatti S, Brünken S, Joblin C. Direct Evidence of the Benzylium and Tropylium Cations as the Two Long-Lived Isomers of C 7 H 7. Chemphyschem 2018; 19:3182-3185. [PMID: 30238585 PMCID: PMC6420061 DOI: 10.1002/cphc.201800744] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Indexed: 11/12/2022]
Abstract
Disentangling the isomeric structure of C7 H7 + is a longstanding experimental issue. We report here the full mid-infrared vibrational spectrum of C7 H7 + tagged with Ne obtained with infrared-predissociation spectroscopy at 10 K. Saturation depletion measurements were used to assign the contribution of benzylium and tropylium isomers and demonstrate that no other isomer is involved. Recorded spectral features compare well with density functional theory calculations. This opens perspectives for a better understanding and control of the formation paths leading to either tropylium or benzylium ions.
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Affiliation(s)
- Pavol Jusko
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse (UPS), CNRS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
| | - Aude Simon
- Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, 31062 Toulouse, France
| | - Shreyak Banhatti
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - Sandra Brünken
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525 ED, Nijmegen, The Netherlands
| | - Christine Joblin
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse (UPS), CNRS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
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Wagner JP, McDonald DC, Duncan MA. Mid-Infrared Spectroscopy of C 7H 7+ Isomers in the Gas Phase: Benzylium and Tropylium. J Phys Chem Lett 2018; 9:4591-4595. [PMID: 30059230 DOI: 10.1021/acs.jpclett.8b02121] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Both prominent C7H7+ isomers, the benzylium and the tropylium cations, were generated in an electrical discharge/supersonic expansion from toluene and cycloheptatriene precursors. Their infrared spectra were measured in the region of 1000-3500 cm-1 using photodissociation of the respective argon- and nitrogen-tagged complexes with a broadly tunable OPO/OPA laser system. Spectral signatures of both isomers were observed independent of the precursor, albeit in different relative intensities. The spectra were assigned based on scaled harmonic B3LYP-D3/cc-pVTZ frequency computations and comparisons to previous experimental studies. Consistent with its high symmetry, only two bands were observed for the (nitrogen-tagged) tropylium ion at 3036 and 1477 cm-1, corresponding to C-H stretching and C-C-H deformation/C═C stretching vibrations, respectively. Furthermore, the C-H stretching region of the benzylium ion is reported for the first time.
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Affiliation(s)
- J Philipp Wagner
- Department of Chemistry , University of Georgia , 140 Cedar Street , Athens , Georgia 30602 , United States
| | - David C McDonald
- Department of Chemistry , University of Georgia , 140 Cedar Street , Athens , Georgia 30602 , United States
| | - Michael A Duncan
- Department of Chemistry , University of Georgia , 140 Cedar Street , Athens , Georgia 30602 , United States
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8
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Vala M, Oomens J, Berden G. Structure and Dissociation Pathways of Protonated Tetralin (1,2,3,4-Tetrahydronaphthalene). J Phys Chem A 2017; 121:4606-4612. [PMID: 28574713 DOI: 10.1021/acs.jpca.7b01858] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The infrared multiple-photon dissociation (IRMPD) spectrum of protonated tetralin (1,2,3,4-tetrahydronaphthalene, THN) has been recorded using an infrared free electron laser coupled to a Fourier transform ion cyclotron mass spectrometer. IR-induced fragmentation of the protonated parent [THN + H] +, m/z 133, yielded a single fragment ion at m/z 91. No evidence for fragment ions at m/z 131 or 132 was observed, indicating that protonated THN ejects neither atomic H nor molecular H2. Comparison of the experimental spectrum with density functional calculations (B3LYP/6-311++G(d,p)) of the two possible protonated isomers identifies a preference for the position of protonation. Possible decomposition pathways starting from both [THN + H(5)]+ and [THN + H(6)]+ are investigated. The potential energy profiles computed for these decomposition routes reveal that (1) the m/z 91 ionic product resembles the benzylium ion, but with the extra hydrogen and the methylene substituents in various ortho, meta, and para conformations around the aromatic ring and that (2) the decomposition process involving the [THN + H(6)]+ isomer is predominant, while the one involving the [THN + H(5)]+ may play a smaller role. Potential energy pathways from the initial decomposition product(s) to the benzylium and tropylium ions have also been computed. Given the relatively low barriers to these ions, it is concluded that the benzylium ion and, with sufficient activation, the tropylium ion plus neutral propene are the final products.
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Affiliation(s)
- Martin Vala
- Department of Chemistry and Center for Chemical Physics, University of Florida , Gainesville, Florida 32611-7200, United States
| | - Jos Oomens
- Radboud University , Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, NL-6525 ED Nijmegen, The Netherlands
| | - Giel Berden
- Radboud University , Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, NL-6525 ED Nijmegen, The Netherlands
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9
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Li J, Nye LC, Wasserthal LK, Vinh C, Kirschbaum RW, Ivanović-Burmazović I, Hirsch A, Drewello T. Formation of Highly Charged Quasi-Molecular Ions of a Polycationic [60]Fullerene Hexakis-Adduct and Their Fragmentation Behavior in the Gas Phase. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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10
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Féraud G, Dedonder-Lardeux C, Soorkia S, Jouvet C. Photo-fragmentation spectroscopy of benzylium and 1-phenylethyl cations. J Chem Phys 2014; 140:024302. [PMID: 24437872 DOI: 10.1063/1.4858409] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The electronic spectra of cold benzylium (C6H5-CH2 (+)) and 1-phenylethyl (C6H5-CH-CH3 (+)) cations have been recorded via photofragment spectroscopy. Benzylium and 1-phenylethyl cations produced from electrosprayed benzylamine and phenylethylamine solutions, respectively, were stored in a cryogenically cooled quadrupole ion trap and photodissociated by an OPO laser, scanned in parts of the UV and visible regions (600-225 nm). The electronic states and active vibrational modes of the benzylium and 1-phenylethyl cations as well as those of their tropylium or methyl tropylium isomers have been calculated with ab initio methods for comparison with the spectra observed. Sharp vibrational progressions are observed in the visible region while the absorption features are much broader in the UV. The visible spectrum of the benzylium cation is similar to that obtained in an argon tagging experiment [V. Dryza, N. Chalyavi, J. A. Sanelli, and E. J. Bieske, J. Chem. Phys. 137, 204304 (2012)], with an additional splitting assigned to Fermi resonances. The visible spectrum of the 1-phenylethyl cation also shows vibrational progressions. For both cations, the second electronic transition is observed in the UV, around 33,000 cm(-1) (4.1 eV) and shows a broadened vibrational progression. In both cases the S2 optimized geometry is non-planar. The third electronic transition observed around 40,000 cm(-1) (5.0 eV) is even broader with no apparent vibrational structures, which is indicative of either a fast non-radiative process or a very large change in geometry between the excited and the ground states. The oscillator strengths calculated for tropylium and methyl tropylium are weak. Therefore, these isomeric structures are most likely not responsible for these absorption features. Finally, the fragmentation pattern changes in the second and third electronic states: C2H2 loss becomes predominant at higher excitation energies, for both cations.
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Affiliation(s)
- Géraldine Féraud
- Physique des Interactions Ioniques et Moleculaires, UMR CNRS 7345, Aix-Marseille Université, Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France
| | - Claude Dedonder-Lardeux
- Physique des Interactions Ioniques et Moleculaires, UMR CNRS 7345, Aix-Marseille Université, Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France
| | - Satchin Soorkia
- Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud 11, 91405 Orsay Cedex, France
| | - Christophe Jouvet
- Physique des Interactions Ioniques et Moleculaires, UMR CNRS 7345, Aix-Marseille Université, Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France
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11
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Seo J, Kim SJ, Shin SK. Coupled unimolecular dissociation kinetics of bromotoluene radical cations. J Phys Chem A 2013; 117:11924-32. [PMID: 23914840 DOI: 10.1021/jp4031442] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The unimolecular dissociations of o-, m-, and p-bromotoluene radical cations to C7H7(+) (benzylium and tropylium) are examined by considering the coupling of the three isomers in the dissociation pathways. The potential energy surface obtained from ab initio calculations suggests the interconversion of isomers through methylene and hydrogen migrations on the ring. The rate equations for each isomer are combined together to form a rate matrix for coupled reactions. The rate matrix contains the microcanonical rate constants for all elementary steps, which are calculated using Rice-Ramsperger-Kassel-Marcus theory based on the molecular parameters obtained from density functional theory. The unimolecular dissociation rates for coupled reactions are determined by numerically solving the matrix equation. As a result of reaction coupling, the product branching ratio becomes time-dependent and the reaction rates of three isomers become parallel to one another as the energy increases, although their initial rates differently vary with energy. The calculated rate-energy curves fall below the time-resolved photodissociation data in the energy range 2.2-2.7 eV but are in line with the photoelectron photoion coincidence data in the energy range 2.7-3.5 eV. The discrepancy between experiment and theory in the low-energy region is ascribed to the uncertainties of the potential energy surface as well as the contribution of the radiative relaxation rate that has not been taken into account in the theoretical calculations. The rate-energy curves are then used to calculate the thermal reaction rate constants, and the Arrhenius parameters are determined in the temperature range 700-1300 K. Comparison of the activation energy and entropy obtained from the Arrhenius plot with the calculated enthalpy and entropy changes between the reactant and the highest-lying transition state suggests that a series of [1,2] H-atom migrations occurring near the entrance comprise the rate-determining steps and the subsequent [1,2] H-atom migrations play an important role in increasing the activation energy and decreasing the entropy by reducing the net flux to the exit.
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Affiliation(s)
- Jongcheol Seo
- Department of Chemistry, Pohang University of Science and Technology , Pohang, Korea 789-784
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Dryza V, Chalyavi N, Sanelli JA, Bieske EJ. Electronic absorptions of the benzylium cation. J Chem Phys 2013. [PMID: 23206000 DOI: 10.1063/1.4767402] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The electronic transitions of the benzylium cation (Bz(+)) are investigated over the 250-550 nm range by monitoring the photodissociation of mass-selected C(7)H(7)(+)-Ar(n) (n = 1, 2) complexes in a tandem mass spectrometer. The Bz(+)-Ar spectrum displays two distinct band systems, the S(1)←S(0) band system extending from 370 to 530 nm with an origin at 19,067 ± 15 cm(-1), and a much stronger S(3)←S(0) band system extending from 270 to 320 nm with an origin at 32,035 ± 15 cm(-1). Whereas the S(1)←S(0) absorption exhibits well resolved vibrational progressions, the S(3)←S(0) absorption is broad and relatively structureless. Vibronic structure of the S(1)←S(0) system, which is interpreted with the aid of time-dependent density functional theory and Franck-Condon simulations, reflects the activity of four totally symmetric ring deformation modes (ν(5), ν(6), ν(9), ν(13)). We find no evidence for the ultraviolet absorption of the tropylium cation, which according to the neon matrix spectrum should occur over the 260 - 275 nm range [A. Nagy, J. Fulara, I. Garkusha, and J. Maier, Angew. Chem., Int. Ed. 50, 3022 (2011)].
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Affiliation(s)
- Viktoras Dryza
- School of Chemistry, The University of Melbourne, Victoria 3010, Australia
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Li F, Zhang X, Zhang H, Jiang K. Gas-phase fragmentation of the protonated benzyl ester of proline: intramolecular electrophilic substitution versus hydride transfer. JOURNAL OF MASS SPECTROMETRY : JMS 2013; 48:423-429. [PMID: 23584935 DOI: 10.1002/jms.3162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 12/11/2012] [Accepted: 12/19/2012] [Indexed: 06/02/2023]
Abstract
In this study, the gas phase chemistry of the protonated benzyl esters of proline has been investigated by electrospray ionization mass spectrometry and theoretical calculation. Upon collisional activation, the protonated molecules undergo fragmentation reactions via three primary channels: (1) direct decomposition to the benzyl cation (m/z 91), (2) formation of an ion-neutral complex of [benzyl cation + proline](+), followed by a hydride transfer to generate the protonated 4,5-dihydro-3H-pyrrole-2-carboxylic acid (m/z 114), and (3) electrophilic attack at the amino by the transferring benzyl cation, and the subsequent migration of the activated amino proton leading to the simultaneous loss of (H2O + CO). Interestingly, no hydrogen/deuterium exchange for the fragment ion m/z 114 occurs in the d-labeling experiments, indicating that the transferring hydride in path-b comes from the methenyl hydrogen rather than the amino hydrogen. For para-substituted benzyl esters, the presence of electron-donating substituents significantly promotes the direct decomposition (path-a), whereas the presence of electron-withdrawing ones distinctively inhibits that channel. For the competing channels of path-b and path-c, the presence of electron-donating substituents favors path-b rather than path-c, whereas the presence of electron-withdrawing ones favors path-c rather than path-b.
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Affiliation(s)
- Fei Li
- Key Laboratory of Organosilicon Chemistry and Material Technology, Hangzhou Normal University, Hangzhou, 310012, China
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You Z, Guo C, Pan Y. An experimental and theoretical study on fragmentation of protonated N-(2-pyridinylmethyl)indole in electrospray ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:2509-2516. [PMID: 23008068 DOI: 10.1002/rcm.6371] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
RATIONALE The dissociation reactions of protonated molecules are the base of structural analysis in electrospray ionization tandem mass spectrometry (ESI-MS(n)). However, general rules for elucidating the numerous fragmentation reactions in ESI-MS(n) are still rather lacking. Therefore, it is very important at all times to carry out mechanistic investigations for fragmentation reactions in the gas phase. METHODS The fragmentation reactions of protonated N-(2-pyridinylmethyl)indoles were studied by both of ESI ion trap tandem mass spectrometry and ESI Fourier transform ion cyclotron resonance tandem mass spectrometry in positive-ion mode. RESULTS In ESI-MS/MS, the ionizing proton is first bound to the most thermodynamically favored site, the pyridine nitrogen; then it transfers to the dissociative protonation sites and triggers the fragmentation. In the fragmentation of the target compounds, some interesting reactions, such as rearrangement, proton transfer and electron transfer reactions, take place via ion/neutral complexes. The proposed mechanisms are supported by both theoretical calculations and isotopic labeling experiments. CONCLUSIONS This study is a case for better understanding the dissociative protonation sites and enriching the knowledge about the role of ion/neutral complexes in ESI-MS. It also provides useful information for the structural analysis of organic compounds, especially drug analysis in pharmaceutical chemistry.
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Affiliation(s)
- Zhushuang You
- Department of Chemistry, Zhejiang University, Hangzhou, China
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Chai Y, Wang L, Sun H, Guo C, Pan Y. Gas-phase chemistry of benzyl cations in dissociation of N-benzylammonium and N-benzyliminium ions studied by mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:823-833. [PMID: 22367690 DOI: 10.1007/s13361-012-0344-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 01/16/2012] [Accepted: 01/20/2012] [Indexed: 05/31/2023]
Abstract
In this study, the fragmentation reactions of various N-benzylammonium and N-benzyliminium ions were investigated by electrospray ionization mass spectrometry. In general, the dissociation of N-benzylated cations generates benzyl cations easily. Formation of ion/neutral complex intermediates consisting of the benzyl cations and the neutral fragments was observed. The intra-complex reactions included electrophilic aromatic substitution, hydride transfer, electron transfer, proton transfer, and nucleophilic aromatic substitution. These five types of reactions almost covered all the potential reactivities of benzyl cations in chemical reactions. Benzyl cations are well-known as Lewis acid and electrophile in reactions, but the present study showed that the gas-phase reactivities of some suitably ring-substituted benzyl cations were far richer. The 4-methylbenzyl cation was found to react as a Brønsted acid, benzyl cations bearing a strong electron-withdrawing group were found to react as electron acceptors, and para-halogen-substituted benzyl cations could react as substrates for nucleophilic attack at the phenyl ring. The reactions of benzyl cations were also related to the neutral counterparts. For example, in electron transfer reaction, the neutral counterpart should have low ionization energy and in nucleophilic aromatic substitution reaction, the neutral counterpart should be piperazine or analogues. This study provided a panoramic view of the reactions of benzyl cations with neutral N-containing species in the gas phase.
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Affiliation(s)
- Yunfeng Chai
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, 310027, China
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16
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Chiavarino B, Crestoni ME, Dopfer O, Maitre P, Fornarini S. Benzylium versus Tropylium Ion Dichotomy: Vibrational Spectroscopy of Gaseous C8H9+ Ions. Angew Chem Int Ed Engl 2012; 51:4947-9. [DOI: 10.1002/anie.201200558] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Indexed: 11/08/2022]
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Chiavarino B, Crestoni ME, Dopfer O, Maitre P, Fornarini S. Benzylium versus Tropylium Ion Dichotomy: Vibrational Spectroscopy of Gaseous C8H9+ Ions. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201200558] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Halbert S, Bouchoux G. Isomerization and Dissociation of n-Butylbenzene Radical Cation. J Phys Chem A 2012; 116:1307-15. [DOI: 10.1021/jp211673f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stéphanie Halbert
- Laboratoire des Mécanismes
Réactionnels,
Ecole Polytechnique, CNRS, 91128 Palaiseau,
France
| | - Guy Bouchoux
- Laboratoire des Mécanismes
Réactionnels,
Ecole Polytechnique, CNRS, 91128 Palaiseau,
France
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Chai Y, Guo C, Jiang K, Pan Y, Sun C. Cα–Cβand Cα–N bond cleavage in the dissociation of protonated N–benzyllactams: dissociative proton transfer and intramolecular proton-transport catalysis. Org Biomol Chem 2012; 10:791-7. [DOI: 10.1039/c1ob06020a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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20
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Chai Y, Sun H, Pan Y, Sun C. N-centered odd-electron ions formation from collision-induced dissociation of electrospray ionization generated even-electron ions: single electron transfer via ion/neutral complex in the fragmentation of protonated N,N'-dibenzylpiperazines and protonated N-benzylpiperazines. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:1526-1533. [PMID: 21953256 DOI: 10.1007/s13361-011-0176-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 05/19/2011] [Accepted: 05/19/2011] [Indexed: 05/31/2023]
Abstract
Single electron transfer (SET) via ion/neutral complex (INC) was proposed and confirmed to be the key step in the formation of N-centered odd-electron ions from fragmentation of protonated even-electron ions in the present study. Upon collisional activation, the model compounds, protonated N,N'-dibenzylpiperazine and protonated N-benzylpiperazines initially dissociated to form intermediate INCs consisting of N-benzylpiperazine (or piperazine) and benzyl cation. In these ion/neutral complexes, SET reaction and direct separation as well as other reactions were observed and characterized experimentally and theoretically. Density functional theory calculations demonstrated that the energy requirement for homolysis of the precursor ion was so large that it could not be achieved, whereas the heterolytic dissociation followed by electron transfer via INC was energetically preferred. The SET process occurred only when the radical products were more stable than the separation products. The energy barrier for SET in the compounds studied was roughly estimated by comparison with other competing reactions. When the INC contained electron donor with lower ionization energy and electron acceptor with higher electron affinity, the SET reaction was more efficient.
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Affiliation(s)
- Yunfeng Chai
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, 310027, China
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Chai Y, Jiang K, Sun C, Pan Y. Gas-Phase Nucleophilic Aromatic Substitution between Piperazine and Halobenzyl Cations: Reactivity of the Methylene Arenium Form of Benzyl Cations. Chemistry 2011; 17:10820-4. [DOI: 10.1002/chem.201101790] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Indexed: 11/10/2022]
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22
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Zins EL, Milko P, Schröder D, Aysina J, Ascenzi D, Žabka J, Alcaraz C, Price SD, Roithová J. Formation of Organoxenon Dications in the Reactions of Xenon with Dications Derived from Toluene. Chemistry 2011; 17:4012-20. [DOI: 10.1002/chem.201002556] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Indexed: 11/11/2022]
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Weitzel KM. Bond-dissociation energies of cations--pushing the limits to quantum state resolution. MASS SPECTROMETRY REVIEWS 2011; 30:221-235. [PMID: 21337598 DOI: 10.1002/mas.20276] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 07/21/2009] [Accepted: 07/21/2009] [Indexed: 05/30/2023]
Abstract
Currently available concepts for measuring the bond-dissociation energy of cations D(o) are reviewed. Starting from the traditional approach of directly measuring the threshold energy for the appearance of fragment ions, attention is directed towards indirect measurements, where threshold energies are obtained by extrapolation of, for example, rate constants k(E) or kinetic energy release (KER) data to the threshold of interest. More recent high precision techniques again utilize direct measurements, for example, of the disappearance energy of the parent ion. Most precise data are obtained from quantum state resolved measurements of the dissociation energy, where the threshold energy is bracketed by the existing quantum states above and below the threshold. Ultimately the limits can even be pushed beyond the bracketing limit, by investigating steps on the lineshape of homogeneously broadened single rotational transitions.
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Nagy A, Fulara J, Garkusha I, Maier JP. On the benzylium/tropylium ion dichotomy: electronic absorption spectra in neon matrices. Angew Chem Int Ed Engl 2011; 50:3022-5. [PMID: 21404390 DOI: 10.1002/anie.201008036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Indexed: 11/09/2022]
Affiliation(s)
- Adam Nagy
- Departement Chemie, Universität Basel, Basel, Switzerland
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Nagy A, Fulara J, Garkusha I, Maier JP. On the Benzylium/Tropylium Ion Dichotomy: Electronic Absorption Spectra in Neon Matrices. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201008036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Zins EL, Pepe C, Schröder D. Energy-dependent dissociation of benzylpyridinium ions in an ion-trap mass spectrometer. JOURNAL OF MASS SPECTROMETRY : JMS 2010; 45:1253-1260. [PMID: 20967739 DOI: 10.1002/jms.1847] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 09/10/2010] [Indexed: 05/30/2023]
Abstract
Benzylpyridinium ions, generated via electrospray ionization of dilute solutions of their salts in acetonitrile/water, are probed by collisional activation in an ion-trap mass spectrometer. From the breakdown diagrams obtained, phenomenological appearance energies of the fragment ions are derived. Comparison of the appearance energies with calculated reaction endothermicities shows a reasonably good correlation for this particular class of compounds. In addition, the data indirectly indicate that at threshold the dissociation of almost all of the benzylpyridinium ions under study leads to the corresponding benzylium ions, rather than the tropylium isomers. Substituent effects on the fragmentation for a series of benzylpyridinium ions demonstrate that neither mass effects nor differences in density of states seriously affect the energetics derived from the ion-trap experiments.
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Affiliation(s)
- Emilie-Laure Zins
- Institute of Organic Chemistry and Biochemistry, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
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Chai Y, Jiang K, Pan Y. Hydride transfer reactions via ion-neutral complex: fragmentation of protonated N-benzylpiperidines and protonated N-benzylpiperazines in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2010; 45:496-503. [PMID: 20301171 DOI: 10.1002/jms.1731] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
An ion-neutral complex (INC)-mediated hydride transfer reaction was observed in the fragmentation of protonated N-benzylpiperidines and protonated N-benzylpiperazines in electrospray ionization mass spectrometry. Upon protonation at the nitrogen atom, these compounds initially dissociated to an INC consisting of [RC(6)H(4)CH(2)](+) (R = substituent) and piperidine or piperazine. Although this INC was unstable, it did exist and was supported by both experiments and density functional theory (DFT) calculations. In the subsequent fragmentation, hydride transfer from the neutral partner to the cation species competed with the direct separation. The distribution of the two corresponding product ions was found to depend on the stabilization energy of this INC, and it was also approved by the study of substituent effects. For monosubstituted N-benzylpiperidines, strong electron-donating substituents favored the formation of [RC(6)H(4)CH(2)](+), whereas strong electron-withdrawing substituents favored the competing hydride transfer reaction leading to a loss of toluene. The logarithmic values of the abundance ratios of the two ions were well correlated with the nature of the substituents, or rather, the stabilization energy of this INC.
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Affiliation(s)
- Yunfeng Chai
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
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Zins EL, Pepe C, Schröder D. Methylene-transfer reactions of benzylium/tropylium ions with neutral toluene studied by means of ion-trap mass spectrometry. Faraday Discuss 2010. [DOI: 10.1039/b907236e] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Zins EL, Rondeau D, Karoyan P, Fosse C, Rochut S, Pepe C. Investigations of the fragmentation pathways of benzylpyridinium ions under ESI/MS conditions. JOURNAL OF MASS SPECTROMETRY : JMS 2009; 44:1668-1675. [PMID: 19824036 DOI: 10.1002/jms.1672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Benzylpyridinium ions are often used as 'thermometer ions' in order to evaluate the internal energy distribution of the ions formed in sources of mass spectrometers. However, the detailed fragmentation pathways of these parent ions were not well established. In particular, fragmentation involving a rearrangement (RR) process may be influencing the simulated distribution curves. In a previous study, we suggested that such RR actually occurred under electrospray ionization/mass spectrometry (ESI/MS) and fast atom bombardment/mass spectrometry (FAB/MS) experiments. Here, we present a systematic study of different substituted benzylpyridinium ions. Theoretical calculations showed that RR fragmentation leading to substituted tropylium ions could occur under 'soft ionization' conditions, such as ESI or FAB. Experimental results obtained under gas-phase reactivity conditions showed that some substituted benzylpiridinium compounds actually undergo RR fragmentations under ESI/MS conditions. Mass-analyzed kinetic experiments were also carried out to gain information on the reaction pathways that actually occur, and these experimental results are in agreement with the reaction pathways theoretically proposed.
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Affiliation(s)
- Emilie-Laure Zins
- Université Pierre et Marie Curie, Laboratoire de Dynamique, Interactions et réactivité, 4 place Jussieu, Paris, 75005, France.
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Žabka J, Polášek M, Ascenzi D, Tosi P, Roithová J, Schröder D. Reactivity of C2H5+ with Benzene: Formation of Ethylbenzenium Ions and Implications for Titan’s Ionospheric Chemistry. J Phys Chem A 2009; 113:11153-60. [DOI: 10.1021/jp905052h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Jan Žabka
- J. Heyrovský Institute of Physical Chemistry, V. Čermák Laboratory, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic, Department of Organic Chemistry, Faculty of Sciences, Charles University in Prague, Hlavova 8, 12083 Prague 2, Czech Republic, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic, and Department of Physics, University of Trento, Via Sommarive 14 38100 Povo,
| | - Miroslav Polášek
- J. Heyrovský Institute of Physical Chemistry, V. Čermák Laboratory, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic, Department of Organic Chemistry, Faculty of Sciences, Charles University in Prague, Hlavova 8, 12083 Prague 2, Czech Republic, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic, and Department of Physics, University of Trento, Via Sommarive 14 38100 Povo,
| | - Daniela Ascenzi
- J. Heyrovský Institute of Physical Chemistry, V. Čermák Laboratory, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic, Department of Organic Chemistry, Faculty of Sciences, Charles University in Prague, Hlavova 8, 12083 Prague 2, Czech Republic, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic, and Department of Physics, University of Trento, Via Sommarive 14 38100 Povo,
| | - Paolo Tosi
- J. Heyrovský Institute of Physical Chemistry, V. Čermák Laboratory, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic, Department of Organic Chemistry, Faculty of Sciences, Charles University in Prague, Hlavova 8, 12083 Prague 2, Czech Republic, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic, and Department of Physics, University of Trento, Via Sommarive 14 38100 Povo,
| | - Jana Roithová
- J. Heyrovský Institute of Physical Chemistry, V. Čermák Laboratory, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic, Department of Organic Chemistry, Faculty of Sciences, Charles University in Prague, Hlavova 8, 12083 Prague 2, Czech Republic, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic, and Department of Physics, University of Trento, Via Sommarive 14 38100 Povo,
| | - Detlef Schröder
- J. Heyrovský Institute of Physical Chemistry, V. Čermák Laboratory, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic, Department of Organic Chemistry, Faculty of Sciences, Charles University in Prague, Hlavova 8, 12083 Prague 2, Czech Republic, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic, and Department of Physics, University of Trento, Via Sommarive 14 38100 Povo,
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31
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Baytekin B, Baytekin H, Hahn U, Reckien W, Kirchner B, Schalley C. Dendrimer Disassembly in the Gas Phase: A Cascade Fragmentation Reaction of Fréchet Dendrons. Chemistry 2009; 15:7139-49. [DOI: 10.1002/chem.200900403] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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32
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CHENG X, ZHAO Y, LI F, ZHANG D. A Theoretical Investigation on the Reaction Mechanism of the C 9H 12+·Side-chain Decomposition. CHINESE J CHEM 2009. [DOI: 10.1002/cjoc.200990108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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33
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Zins EL, Pepe C, Rondeau D, Rochut S, Galland N, Tabet JC. Theoretical and experimental study of tropylium formation from substituted benzylpyridinium species. JOURNAL OF MASS SPECTROMETRY : JMS 2009; 44:12-17. [PMID: 18615775 DOI: 10.1002/jms.1461] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Fragmentation pathways of unsubstituted and substituted benzylpyridinium compounds were investigated using mass-analysed kinetic energy (MIKE) technique in combination with high level of quantum chemical calculations in the gas phase. Fast atom bombardment (FAB) source was used for ionisation of the studied compounds. The formation of both benzylium and tropylium species were investigated. Hybrid Hartree-Fock/Density Functional Theory calculations have been performed to assess the geometries and the energies of the transition states and intermediates. For each cases, different reaction pathways were investigated, and particularly in the case of the formation of tropylium species, the formation of the seven-membered ring before or after the loss of pyridine were studied. The effect of para-methyl and para-methoxy substituents on the activation energy of the rearrangement process to form thermodynamically stable tropylium compounds has been studied. Theoretical calculations showed competition between direct bond cleavage and rearrangement reactions to form benzylium and tropylium compounds, respectively. Experimental results also suggested that the rearrangement process takes place to yield stable tropylium under "soft ionisation techniques", such as FAB.
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Affiliation(s)
- Emilie-Laure Zins
- Laboratoire de Dynamique Interactions et Réactivité LADIR, Université Pierre et Marie Curie, Case Courrier 49, CNRS, UMR 7075, Paris, France.
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Choe JC. Formation of C7H7(+) from benzyl chloride and chlorotoluene molecular ions: a theoretical study. J Phys Chem A 2008; 112:6190-7. [PMID: 18543898 DOI: 10.1021/jp802641c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The potential energy surface (PES) for the formation of C7H7(+) from benzyl chloride and chlorotoluene ions was obtained by quantum chemical calculations at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d) level. On the basis of the PES, the RRKM model calculations were carried out to predict the rate constants of the dissociations of the molecular ions of o-, m-, and p-chlorotoluene, all of which agreed well with previous experimental results. The kinetic analysis showed that the benzylium ion was the predominant product in the dissociations of the four isomeric molecular ions, below the thresholds of the formation of tolylium ions.
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Affiliation(s)
- Joong Chul Choe
- Department of Chemistry, Dongguk University, Seoul 100-715, Korea.
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35
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Ghiasi R. Theoretical study of classical isomers tropylium, azatropylium, phosphatropylium, and arsatropylium cations: structure, properties and aromaticity. MAIN GROUP CHEMISTRY 2008. [DOI: 10.1080/10241220802436271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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36
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Fileti EE, Moraes PRP, Domingues L, Riveros JM. Gas-phase electrophilic addition promoted by CH(3)S(+)=CH(2) ions on aromatic systems. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:1310-8. [PMID: 17902105 DOI: 10.1002/jms.1202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The gas-phase methylenation reaction between CH(3)S(+)=CH(2) and alkylbenzenes, aniline, phenol and alkyl phenyl ethers, which yields [M + CH](+) and CH(3)SH, has been studied by Fourier transform ion cyclotron resonance (FT-ICR) techniques and computational chemistry at the DFT level. The methylthiomethyl cation is less reactive than methoxymethyl and, unlike the latter, is unreactive toward benzene. The calculations suggest that reaction with toluene should proceed primarily by addition at the para and ortho positions resulting in a benzyl-type ion. Reaction with aniline-2,3,4,5,6-d(5) reveals that elimination of CH(3)SD is kinetically favored by a factor of 5 over elimination of CH(3)SH. Experiments with C(6)H(6)ND(2) and theoretical calculations suggest that methylenation at the nitrogen atom is energetically favorable and likely, but the observed results may reflect some H/D scrambling, which occurs after attack at a ring position. By comparison, reaction with phenol-2,3,4,5,6-d(5) reveals that methylenation followed by elimination of CH(3)SD is kinetically favored by a factor of 3.8 over elimination of CH(3)SH. For phenol, the theoretical calculations suggest that attack by CH(3)S(+)=CH(2) at the para or ortho position is the only low-energy pathway for methylenation. However, a low-energy pathway for hydrogen scrambling is predicted by the calculations originating from the exit complex, [CH(3)SH(...) CH(2)=C(6)H(4)=OH](+), of reaction at a ring position.
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Affiliation(s)
- Eudes E Fileti
- Institute of Chemistry, University of São Paulo, Av. Lineu Prestes 748, Cidade Universitária, São Paulo, Brazil, CEP 05508-900, Brazil
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37
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Choe JC. Isomerization and dissociation of ethylbenzene and xylene molecular ions: A DFT study. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2006.12.086] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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38
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Ghiasi R. Theoretical studies on the structures, properties, and aromaticity of germatropylium cations. MAIN GROUP CHEMISTRY 2006. [DOI: 10.1080/10241220701458384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Chiavarino B, Crestoni ME, Fornarini S, Dopfer O, Lemaire J, Maître P. IR Spectroscopic Features of Gaseous C7H7O+ Ions: Benzylium versus Tropylium Ion Structures. J Phys Chem A 2006; 110:9352-60. [PMID: 16869683 DOI: 10.1021/jp0628380] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gaseous [C7H7O]+ ions have been formed by protonation of benzaldehyde or tropone (2,4,6-cycloheptatrienone) in the cell of an FT-ICR mass spectrometer using C2H5(+) as a Brønsted acid. The so-formed species have been assayed by infrared multiphoton dissociation (IRMPD) using the free electron laser (FEL) at the CLIO (Centre Laser Infrarouge Orsay) facility. The IRMPD features are quite distinct for ions from the two different precursors, pointing to two different isomers. A number of potential structures for [C7H7O]+ ions have been optimized at the B3LYP/6-31+G(d,p) level of theory, and their relative energies and IR spectra are reported. On this basis, the IRMPD spectra of [C7H7O]+ ions are found to display features characteristic of O-protonated species, with no evidence of any further skeletal rearrangements. The so-formed ions are thus hydroxy-substituted benzylium and tropylium ions, respectively, representative members of the benzylium/tropylium ion family. The IRMPD assay using the FEL laser light has allowed their unambiguous discrimination where other mass spectrometric techniques have yielded a less conclusive answer.
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Affiliation(s)
- Barbara Chiavarino
- Dipartimento di Studi di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Università di Roma La Sapienza, P.le A. Moro 5, I-00185 Roma, Italy.
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Abstract
The potential energy surface (PES) for the formation of tropylium and benzylium ions from toluene cation (1) has been explored theoretically. Quantum chemical calculations at the B3LYP/6-311++G and G3//B3LYP levels were performed. A pathway to form o-isotoluene (5-methylene-1,3-cyclohexadiene) cation (5) from 1 was found. The isomerization occurs by two consecutive 1,2-H shifts from CH(3) to the ortho position of the aromatic ring via a distonic benzenium cation (2), which is also an intermediate in the well-known isomerization of 1 to cycloheptatriene cation (4). Since the barrier for the formation of 2 is the highest in the two isomerization pathways, 1, 4, and 5 are interconvertible energetically prior to dissociation. The benzylium ion can be produced via 5 as well as from 1 and the tropylium ion via 4. Rice-Ramsperger-Kassel-Marcus model calculations were carried out based on the obtained PES. The result agrees with previous experimental observations. From a theoretical analysis of kinetics of the isomerizations and dissociations, we suggest that 5 plays an important role in the formation of C(7)H(7)(+) from 1.
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Affiliation(s)
- Joong Chul Choe
- Department of Chemistry, University of Suwon, P.O. Box 77, Suwon 440-600, Korea.
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Fernandez AI, Viggiano AA, Troe J. Two-Channel Dissociation of Chemically and Thermally Activated n-Butylbenzene Cations (C10H14+). J Phys Chem A 2006; 110:8467-76. [PMID: 16821830 DOI: 10.1021/jp056846c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The charge-transfer reaction O(2)(+) + n-butylbenzene (C(10)H(14)) --> O(2) + C(10)H(14)(+) was studied in a turbulent ion flow tube at temperatures between 423 and 548 K and pressures between 15 and 250 Torr in the buffer gases He and N(2). Under chemical activation conditions stabilization vs dissociation ratios S/D of vibrationally highly excited C(10)H(14)(+)* as well as branching ratios of the fragments C(7)H(7)(+) (m/z = 91) vs C(7)H(8)(+) (m/z = 92) of the dissociation of C(10)H(14)(+)* were measured. Under thermal activation conditions, the rate constant of the dominating dissociation channel 92 was measured at 498 and 523 K. Employing information on the specific rate constants k(E) of the two channels 91 and 92 and on collisional energy transfer rates from the literature, the measured S/D curves and branching ratios 91/92 could be modeled well. It is demonstrated that the charge transfer occurs approximately equally through resonant transfer and complex-forming transfer. The thermal dissociation experiments provide a high precision value of the energy barrier for the channel 92, being 1.14 (+/-0.02) eV.
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Affiliation(s)
- Abel I Fernandez
- Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Rd., Hanscom AFB, Massachusetts 01731-3010, USA
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42
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Roithova J, Schröder D, Gruene P, Weiske T, Schwarz H. Structural Aspects of Long-Lived C7H82+ Dications Generated by the Electron Ionization of Toluene. J Phys Chem A 2005; 110:2970-8. [PMID: 16509619 DOI: 10.1021/jp0545288] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The structure of the C7H8(2+) dication generated upon electron ionization of toluene is investigated by experimental and theoretical means. For the long-lived C7H8(2+) dication, the experimental findings obtained with a novel SIFT/GIB instrument suggest complete loss of structural integrity corresponding to the toluene structure. Instead, the manifold of C7H8(2+) dications most likely to be formed is assigned to a mixture of the cycloheptatriene dication and ring-protonated benzylium ions.
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Affiliation(s)
- Jana Roithova
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Praha 8, Czech Republic
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Viggiano AA, Fernandez AI, Troe J. Ion–molecule kinetics at 15–700 Torr. Phys Chem Chem Phys 2005; 7:1533-9. [DOI: 10.1039/b417454b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fernandez AI, Viggiano AA, Miller TM, Williams S, Dotan I, Seeley JV, Troe J. Collisional Stabilization and Thermal Dissociation of Highly Vibrationally Excited C9H12+ Ions from the Reaction O2+ + C9H12 → O2 + C9H12+. J Phys Chem A 2004. [DOI: 10.1021/jp048132s] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Abel I. Fernandez
- Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom AFB, Massachusetts 01731-3010, NRC Research Associateship Program, Keck Center of the National Academies, 500 Fifth Street, NW, GR 322A, Washington, D.C. 20001, Department of Natural Sciences, The Open University of Israel, Ramat Aviv, Tel Aviv, Israel, Department of Chemistry, Oakland University, Rochester, Michigan 48309-4401, and Institute for Physical Chemistry, University of Goettingen, Tammannstrasse 6, D-37077
| | - A. A. Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom AFB, Massachusetts 01731-3010, NRC Research Associateship Program, Keck Center of the National Academies, 500 Fifth Street, NW, GR 322A, Washington, D.C. 20001, Department of Natural Sciences, The Open University of Israel, Ramat Aviv, Tel Aviv, Israel, Department of Chemistry, Oakland University, Rochester, Michigan 48309-4401, and Institute for Physical Chemistry, University of Goettingen, Tammannstrasse 6, D-37077
| | - Thomas M. Miller
- Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom AFB, Massachusetts 01731-3010, NRC Research Associateship Program, Keck Center of the National Academies, 500 Fifth Street, NW, GR 322A, Washington, D.C. 20001, Department of Natural Sciences, The Open University of Israel, Ramat Aviv, Tel Aviv, Israel, Department of Chemistry, Oakland University, Rochester, Michigan 48309-4401, and Institute for Physical Chemistry, University of Goettingen, Tammannstrasse 6, D-37077
| | - S. Williams
- Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom AFB, Massachusetts 01731-3010, NRC Research Associateship Program, Keck Center of the National Academies, 500 Fifth Street, NW, GR 322A, Washington, D.C. 20001, Department of Natural Sciences, The Open University of Israel, Ramat Aviv, Tel Aviv, Israel, Department of Chemistry, Oakland University, Rochester, Michigan 48309-4401, and Institute for Physical Chemistry, University of Goettingen, Tammannstrasse 6, D-37077
| | - I. Dotan
- Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom AFB, Massachusetts 01731-3010, NRC Research Associateship Program, Keck Center of the National Academies, 500 Fifth Street, NW, GR 322A, Washington, D.C. 20001, Department of Natural Sciences, The Open University of Israel, Ramat Aviv, Tel Aviv, Israel, Department of Chemistry, Oakland University, Rochester, Michigan 48309-4401, and Institute for Physical Chemistry, University of Goettingen, Tammannstrasse 6, D-37077
| | - J. V. Seeley
- Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom AFB, Massachusetts 01731-3010, NRC Research Associateship Program, Keck Center of the National Academies, 500 Fifth Street, NW, GR 322A, Washington, D.C. 20001, Department of Natural Sciences, The Open University of Israel, Ramat Aviv, Tel Aviv, Israel, Department of Chemistry, Oakland University, Rochester, Michigan 48309-4401, and Institute for Physical Chemistry, University of Goettingen, Tammannstrasse 6, D-37077
| | - J. Troe
- Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom AFB, Massachusetts 01731-3010, NRC Research Associateship Program, Keck Center of the National Academies, 500 Fifth Street, NW, GR 322A, Washington, D.C. 20001, Department of Natural Sciences, The Open University of Israel, Ramat Aviv, Tel Aviv, Israel, Department of Chemistry, Oakland University, Rochester, Michigan 48309-4401, and Institute for Physical Chemistry, University of Goettingen, Tammannstrasse 6, D-37077
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