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Unimolecular Decomposition Reactions of Picric Acid and its Methylated Derivatives — A DFT Study

Abstract

To handle energetic materials safely, it is important to have knowledge about their sensitivity. Density functional theory (DFT) has proven a valuable tool in the study of energetic materials, and in the current work, DFT is employed study the thermal unimolecular decomposition of 2,4,6-trinitrophenol (picric acid, PA), 3-methyl-2,4,6-trinitrophenol (methyl picric acid, mPA), and 3,5-dimethyl-2,4,6-trinitrophenol (dimethyl picric acid, dmPA). These compounds have similar molecular structures, but according to the literature, mPA is far less sensitive to impact than the other two compounds. Three pathways believed important for the initiation reactions are investigated at 0 K and 298.15 K. We compare the computed energetics of the reaction pathways with the objective of rationalizing the unexpected sensitivity behavior. Our results reveal few if any significant differences in the energetics of the three molecules, and thus do not reflect the sensitivity deviations observed in experiments. These findings point towards the potential importance of crystal structure, crystal morphology, bimolecular reactions, or combinations thereof on the impact sensitivity of nitroaromatics.

Category

Academic article

Client

  • Norwegian Defence Research Establishment / FFI-prosjekt 1531

Language

English

Author(s)

Affiliation

  • Norwegian University of Science and Technology
  • SINTEF Industry / Process Technology
  • Norwegian Defence Research Establishment
  • SINTEF Industry / Materials and Nanotechnology

Date

26.04.2022

Year

2022

Published in

Journal of Physical Chemistry A

ISSN

1089-5639

Volume

126

Page(s)

2645 - 2657

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