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Updated: Mar 30, 2026

On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes
Published on: August 5, 2016
On the formation of pyridine in the interstellar medium
Dorian S N Parker1, Ralf I Kaiser1, Oleg Kostko2
1Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA. ralfk@hawaii.edu.
Abstract:
Nitrogen-substituted polycyclic aromatic hydrocarbons (NPAHs) have been proposed to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block - the aromatic pyridine molecule - has remained elusive for decades. Here we reveal a potential pathway to a facile pyridine (C5H5N) synthesis via the reaction of the cyano vinyl (C2H2CN) radical with vinyl cyanide (C2H3CN) in high temperature environments simulating conditions in carbon-rich circumstellar envelopes of Asymptotic Giant Branch (AGB) stars like IRC+10216. Since this reaction is barrier-less, pyridine can also be synthesized via this bimolecular reaction in cold molecular clouds such as in TMC-1. The synchronized aromatization of precursors readily available in the interstellar medium leading to nitrogen incorporation into the aromatic rings would open up a novel route to pyridine derivatives such as vitamin B3 and pyrimidine bases as detected in carbonaceous chondrites like Murchison.
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