Reaction of CO3-center dot with trinitrotoluene (TNT) in CO2 plasma: Experimental and theoretical study on the formation of [TNT + O](-center dot) and its fragmentation pathways

摘要

It has previously been demonstrated that 2,4,6-trinitrotoluene (TNT) exhibits characteristic reactivity with negative reactant ions generated in air or O-2 during atmospheric-pressure chemical ionization (APCI). For instance, the reaction products were TNT-center dot (m/z 227) for O-2(-center dot), [TNT-H-center dot](-) (m/z 226) for NO3-, and [TNT - OH center dot](-) (m/z210) and [TNT - NO center dot](-) (m/z197) for O-3(-center dot). In this work, reactions of TNT in atmospheric pressure CO2 plasma were examined. [TNT + O](-center dot) (m/z 243) was found as the major ion in addition to TNT-center dot, [TNT + O - OH center dot](-) (m/z226), [TNT + O - O2H center dot](-) (m/z210), [TNT + O - NO center dot](-) (m/z213), and [TNT + O - NO2 center dot](-) (m/z197). Because CO3-center dot was detected as the only reactant ion in CO2 plasma, it was concluded that [TNT + O](-center dot) was formed by the reaction of CO3-center dot with TNT. To elucidate the structure of [TNT + O](-center dot), tandem mass spectrometry analysis for [TNT + O](-center dot) was performed and the fragmentation pathways were examined by density functional theory. It was proposed that the methyl group of TNT migrates flexibly in the ring to afford the observed fragment anions. In the terminal product ion of C7H3O4-(m/z 151), pi orbital electrons in the ring are most delocalized by forming four carbonyl (C=O) bonds and an exo cyclic methylene (C=CH2) group. (C) 2021 Elsevier B.V. All rights reserved.