Self-Reaction of ortho-Benzyne at High Temperatures Investigated by Infrared and Photoelectron Spectroscopy

Florian Hirsch; Engelbert Reusch; Philipp Constantinidis; Ingo Fischer; Sjors Bakels; Anouk M. Rijs; Patrick Hemberger

doi:10.1021/acs.jpca.8b09640

Self-Reaction of ortho-Benzyne at High Temperatures Investigated by Infrared and Photoelectron Spectroscopy

Florian Hirsch, Engelbert Reusch, Philipp Constantinidis, Ingo Fischer, Sjors Bakels, Anouk M. Rijs, Patrick Hemberger

Chemistry and Pharmaceutical Sciences

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

ortho-Benzyne, a Kekulé-type biradical is considered to be a key intermediate in the formation of polycyclic aromatic hydrocarbons (PAH) and soot. In the present work we study the ortho-benzyne self-reactions in a hot microreactor and identify the high-temperature products by IR/UV spectroscopy and by photoion mass-selected threshold photoelectron spectroscopy (ms-TPES) in a free jet. Ms-TPES confirms formation of ortho-benzyne as generated from benzocyclobutenedione, as well as benzene, biphenylene, diacetylene, and acetylene, originating from the reaction o-C ₆ H ₄ → HCC-CCH + C ₂ H ₂ , and CH ₃ . PAH molecules like naphthalene, 2-ethynylnaphthalene, fluorene, phenanthrene, and triphenylene are identified based on their IR/UV spectra. By comparison with recent computations their formation starting from o-benzyne can be readily understood and supports the importance of the biradical addition (1,4-cycloaddition followed by fragmentation) pathway to PAH molecules, recently proposed by Comandini et al.

Original language	English
Pages (from-to)	9563-9571
Number of pages	9
Journal	Journal of Physical Chemistry A
Volume	122
Issue number	49
Early online date	16 Nov 2018
DOIs	https://doi.org/10.1021/acs.jpca.8b09640
Publication status	Published - 13 Dec 2018

Funding

This work was supported by the German Science Foundation, DFG, through Graduiertenkolleg GRK 2112. Furthermore, the research leading to these results has received funding from LASERLAB-EUROPE (Grant Agreement No. 654148, European Union’s Horizon 2020 research and innovation programme. The photoionization experiments were performed at the VUV beamline of the Swiss Light Source, located at the Paul Scherrer Institute (PSI) and were financially also supported by the Swiss Federal Office for Energy (BFE Contract Number SI/501269-01). Patrick Ascher is acknowledged for technical support. We gratefully thank the FELIX staff for their experimental support, and we acknowledge the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) for the support of the FELIX Laboratory.

Funders	Funder number
German Science Foundation
Swiss Federal Office for Energy
Canadian Light Source
Horizon 2020 Framework Programme	654148
Laserlab-Europe
Deutsche Forschungsgemeinschaft	GRK 2112
Bundesamt für Energie	SI/501269-01

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title = "Self-Reaction of ortho-Benzyne at High Temperatures Investigated by Infrared and Photoelectron Spectroscopy",

abstract = " ortho-Benzyne, a Kekul{\'e}-type biradical is considered to be a key intermediate in the formation of polycyclic aromatic hydrocarbons (PAH) and soot. In the present work we study the ortho-benzyne self-reactions in a hot microreactor and identify the high-temperature products by IR/UV spectroscopy and by photoion mass-selected threshold photoelectron spectroscopy (ms-TPES) in a free jet. Ms-TPES confirms formation of ortho-benzyne as generated from benzocyclobutenedione, as well as benzene, biphenylene, diacetylene, and acetylene, originating from the reaction o-C 6 H 4 → HCC-CCH + C 2 H 2 , and CH 3 . PAH molecules like naphthalene, 2-ethynylnaphthalene, fluorene, phenanthrene, and triphenylene are identified based on their IR/UV spectra. By comparison with recent computations their formation starting from o-benzyne can be readily understood and supports the importance of the biradical addition (1,4-cycloaddition followed by fragmentation) pathway to PAH molecules, recently proposed by Comandini et al. ",

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Self-Reaction of ortho-Benzyne at High Temperatures Investigated by Infrared and Photoelectron Spectroscopy

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