Dimerization of the Benzyl Radical in a High-Temperature Pyrolysis Reactor Investigated by IR/UV Ion Dip Spectroscopy

Dimerization of the Benzyl Radical in a High-Temperature Pyrolysis Reactor Investigated by IR/UV Ion Dip Spectroscopy

FELIX researchers Anouk Rijs en Sjors Bakels investigated, in collaboration with Florian Hirsch, Philipp Constantinidis and Ingo Fischer (University of Würzburg), the chemistry of reactive intermediates that are of relevance in combustion processes and in atmospheric chemistry.

By combining isomer-selective, mid-IR action spectroscopy with mass information from UV photoionization, they followed the formation of polycyclic aromatic hydrocarbons (PAHs) from the self-reaction of the benzyl radicals produced at high temperatures (see cover picture). These benzyl radicals are often formed in combustion engines from toluene (an anti-knock additive). The PAHs phenanthrene and fluorene are identified as reaction products. Furthermore, they showed that phenanthrene is formed from bibenzyl via 9,10-dihydrophenanthrene and thus derive a mechanism for the reaction. This work demonstrates an efficient pathway from the benzyl radical to PAH phenanthrene in one bimolecular step only.

The image depicts polycyclic aromatic hydrocarbons produced in the self-reaction of the benzyl radical. Benzyl itself is formed in combustion engines from toluene, an anti-knock additive.

Aknowledgements
This work was supported by the Deutsche Forschungsgemeinschaft. Furthermore, the research leading to these results has received funding from the Seventh Framework Programme and LASERLABEUROPE.

Article
Florian Hirsch, Philipp Constantinidis, Ingo Fischer, Sjors Bakels and Anouk M. Rijs, “Dimerization of the Benzyl Radical in a High-Temperature Pyrolysis Reactor Investigated by IR/UV Ion Dip Spectroscopy”, Chem. Eur. J.(2018) DOI: 10.1002/chem.201800852.

More information: dr. Anouk M. Rijs