Photolysis of 3-Nitro-1,2,4-triazol-5-one: Mechanisms and Products

Hunter W. Schroer, Esteban Londono, Xueshu Li, Hans Joachim Lehmler, William Arnold, Craig L. Just

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Insensitive munitions formulations that include 3-nitro-1,2,4-triazol-5-one (NTO) are replacing traditional explosive compounds. While these new formulations have superior safety characteristics, the compounds have greater environmental mobility, raising concern over potential contamination and cleanup of training and manufacturing facilities. Here, we examine the mechanisms and products of NTO photolysis in simulated sunlight to further inform NTO degradation in sunlit surface waters. We demonstrate that NTO produces singlet oxygen and that dissolved oxygen increases the NTO photolysis rate in deionized water. The rate of NTO photolysis is independent of concentration and decreases slightly in the presence of Suwannee River Natural Organic Matter. The apparent quantum yield of NTO generally decreases as pH increases, ranging from 2.0 × 10-5 at pH 12 to 1.3 × 10-3 at pH 2. Bimolecular reaction rate constants for NTO with singlet oxygen and hydroxyl radical were measured to be (1.95 ± 0.15) × 106 and (3.28 ± 0.23) × 1010 M-1 s-1, respectively. Major photolysis reaction products were ammonium, nitrite, and nitrate, with nitrite produced in nearly stoichiometric yield upon the reaction of NTO with singlet oxygen. Environmental half-lives are predicted to span from 1.1 to 5.7 days. Taken together, these data enhance our understanding of NTO photolysis under environmentally relevant conditions.

Original languageEnglish (US)
Pages (from-to)783-792
Number of pages10
JournalACS Environmental Science and Technology Water
Issue number3
StatePublished - Mar 10 2023
Externally publishedYes

Bibliographical note

Funding Information:
Funding for NTO synthesis was provided by a seed grant from the Water Sustainability Initiative at the University of Iowa, with additional support provided by P30 ES005605 from the National Institute of Environmental Health Sciences/National Institutes of Health. Funding for H.W.S. was provided by an NSF Graduate Research Fellowship, Grant No. 000390183, and by a Presidential Graduate Research Fellowship from the University of Iowa. We would like to acknowledge helpful discussions with David Cwiertny, and we also would like to thank Vic R. Parcell from the High-Resolution Mass Spectrometry Facility at the University of Iowa for help with the HRMS analysis.

Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.


  • bimolecular rate constants
  • IMX-101
  • IMX-104
  • insensitive munitions explosives
  • Nitrotriazolone
  • quenchers
  • singlet oxygen

PubMed: MeSH publication types

  • Journal Article


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