Short communication: Ortho Effect in Electron Ionization Mass Spectrometry of N-Acylanilines Bearing a Proximal Halo Substituent

Electron ionization (EI) mass spectra are not very helpful for characterizing ortho, meta, and para isomers of underivatized haloanilines since their spectra are virtually identical. In contrast, when the amino group of chloro-, bromo-, or iodoanilines is transformed to an N-formyl, N-acetyl, or N-b...

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Bibliographic Details
Published in:Journal of the American Society for Mass Spectrometry 2008-08, Vol.19 (8), p.1114-1118
Main Authors: Jariwala, Freneil B, Figus, Margaret, Attygalle, Athula B
Format: Article
Language:English
Online Access:Get full text
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Summary:Electron ionization (EI) mass spectra are not very helpful for characterizing ortho, meta, and para isomers of underivatized haloanilines since their spectra are virtually identical. In contrast, when the amino group of chloro-, bromo-, or iodoanilines is transformed to an N-formyl, N-acetyl, or N-benzoyl derivative, the spectra of the derivatives reveal a highly dramatic loss of a halogen radical, instead of an HX elimination usually expected from an 'ortho effect.' For example, the spectra of N-formyl, N-acetyl, and N-benzoyl derivatives of ortho isomers of chloro-, bromo-, and iodoanilines show a very prominent peak at m/z 120, 134, and 196, respectively, for the loss of the corresponding halogen atom.
ISSN:1044-0305
DOI:10.1016/j.jasms.2008.05.004