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Photolysis of 3-Nitro-1,2,4-triazol-5-one: Mechanisms and Products
Journal article   Open access   Peer reviewed

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 and Craig L. Just
ACS ES&T water, Vol.3(3), pp.783-792
02/02/2023
DOI: 10.1021/acsestwater.2c00567
PMCID: PMC10012174
PMID: 36936519
url
https://doi.org/10.1021/acsestwater.2c00567View
Published (Version of record) Open Access

Abstract

Insensitive munitions formulations that include 3nitro-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 x 10(-5) at pH 12 to 1.3 x 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) x 10(6) and (3.28 +/- 0.23) x 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.
Nitrotriazolone insensitive munitions explosives IMX-101 IMX-104 singlet oxygen quenchers bimolecular rate constants UIOWA OA Agreement

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