Paramagnetic Resonance Studies of uv and Thermally Induced Radicals in Trinitrotoluene and Dinitrotoluene

Abstract

Electron paramagnetic studies of uv and thermally decomposed 2,4,6 TNT trinitrotoluene (TNT) in the condensed phase show the presence of a triplet spectrum due to an unpaired electron interacting with a nitrogen nucleus. The components of the axially symmetric g and A tensor are; A _⊥ = 4.0 G, A _∥ = 27.0 C, g _⊥ = 2.007 and g” = 2.003. When the decomposed TNT is dissolved in benzene a spectrum with the same spin Hamiltonian parameters is obtained but a further hyperfine interaction with five equivalent hydrogen nuclei is observed. Spectra having the same parameters were also observed when 3,4,5 TNT and 3,5 DNT were dissolved in benzene after decomposition. The spectra are assigned to a radical having an unpaired electron localized on an NO group formed by the removal of an O⁺ from the NO₂ group of TNT. An irreversible decrease of the isotropic hyperfine splitting with the nitrogen nucleus was observed with increasing temperature in the molten phase of TNT. The possible role of this radical in the thermal initiation of explosion is discussed.