Selective Reagent Ion Mass Spectrometric Investigations of the Nitroanilines

David Olivenza-León, Chris A Mayhew, Ramón González-Méndez

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    3 Citations (Scopus)
    31 Downloads (Pure)


    This paper presents an investigation of proton and charge transfer reactions to 2-, 3- and 4-nitroanilines (C 6H 6N 2O 2) involving the reagent ions H 3O +·(H 2O) n (n = 0, 1 and 2) and O 2 +, respectively, as a function of reduced electric field (60–240 Td), using Selective Reagent Ion–Time-of-Flight–Mass Spectrometry (SRI–ToF–MS). To aid in the interpretation of the H 3O +·(H 2O) n experimental data, the proton affinities and gas-phase basicities for the three nitroaniline isomers have been determined using density functional theory. These calculations show that proton transfer from both the H 3O + and H 3O +·H 2O reagent ions to the nitroanilines will be exoergic and hence efficient, with the reactions proceeding at the collisional rate. For proton transfer from H 3O + to the NO 2 sites, the exoergicities are 171 kJ mol −1 (1.8 eV), 147 kJ mol −1 (1.5 eV) and 194 kJ mol −1 (2.0 eV) for 2-, 3- and 4-nitroanilines, respectively. Electron transfer from all three of the nitroanilines is also significantly exothermic by approximately 4 eV. Although a substantial transfer of energy occurs during the ion/molecule reactions, the processes are found to predominantly proceed via non-dissociative pathways over a large reduced electric field range. Only at relatively high reduced electric fields (> 180 Td) is dissociative proton and charge transfer observed. Differences in fragment product ions and their intensities provide a means to distinguish the isomers, with proton transfer distinguishing 2-nitroaniline (2–NA) from 3- and 4-NA, and charge transfer distinguishing 4-NA from 2- and 3-NA, thereby providing a means to enhance selectivity using SRI–ToF–MS. [Figure not available: see fulltext.].

    Original languageEnglish
    Pages (from-to)2259-2266
    Number of pages8
    JournalJournal of the American Society for Mass Spectrometry
    Issue number11
    Early online date9 Sept 2019
    Publication statusPublished - 1 Nov 2019

    Bibliographical note

    This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.


    • Charge transfer
    • Explosives
    • Nitroanilines
    • Proton transfer reaction mass spectrometry
    • Soft chemical i-mass spectrometry

    ASJC Scopus subject areas

    • Structural Biology
    • Spectroscopy


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