Abstract
The kinetics and products of the thermal decomposition of 2,4,6-triazido-3,5-difluoropyridine in melt at temperatures of 120–160°C have been studied using pressure measurements, differential thermal analysis, and IR spectroscopy. The reaction occurs in two macroscopic steps, each described by a first-order kinetic equation. In the first, the activation energy and the common logarithm of the pre-exponential factor are 35.6 ± 1.2 kcal/mol and 15.1 ± 0.6 s–1, respectively. For the studied compound (and certain other heterocyclic azides, such as 2,4,6-triazido-1,3,5-triazine and 2,4,6-triazidopyrimidine), the pre-exponential factor is anomalously high. This is due to the fact that the 2,4,6-triazido-3,5-difluoropyridine molecule contains no hydrogen atoms. For such azides, the usual decomposition mechanism (cleavage of the azide group with subsequent attack of nitrene on a hydrogen atom of a neighboring molecule) is impossible, which favors the stability of the formed nitrene. In this case, the reaction occurs through a complex chain polymerization mechanism, which leads to the formation of specific condensed products: packs of planar polyconjugate carbon–nitrogen networks with a porphyrin-like structure.
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Original Russian Text © V.V. Nedel’ko, N.V. Chukanov, B.L. Korsunskiy, T.S. Larikova, S.V. Chapyshev, V.V. Zakharov, 2018, published in Khimicheskaya Fizika, 2018, Vol. 37, No. 11, pp. 36–41.
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Nedel’ko, V.V., Chukanov, N.V., Korsunskiy, B.L. et al. Kinetics of the Thermal Decomposition of 2,4,6-Triazido-3,5-Difluoropyridine. Russ. J. Phys. Chem. B 12, 997–1002 (2018). https://doi.org/10.1134/S199079311806009X
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DOI: https://doi.org/10.1134/S199079311806009X