Differentiation of isomeric substituted diaryl ethers by electron ionization and chemical ionization mass spectrometry

Bhaskar, G. ; Prabhakar, S. ; Narsaiah, Venkat A. ; Nagaiah, K. ; Ramanjaneyulu, G. S. ; Vairamani, M. (2006) Differentiation of isomeric substituted diaryl ethers by electron ionization and chemical ionization mass spectrometry Rapid Communications in Mass Spectrometry, 12 (3). pp. 161-170. ISSN 0951-4198

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Related URL: http://dx.doi.org/10.1255/ejms.804

Abstract

A series of isomeric substituted diaryl ethers, i.e., 2- or 4-NO2, 5-F-C6H3-O-C6H4 (4-R), where R=H, COCH3, COOCH3, NO2, CHO, OCH3 etc., which comprise ortho and para isomers with respect to the position of the nitro group are studied under GC-EI-MS and CI-MS conditions. The EI mass spectra of ortho and para isomers show distinct fragment ions, where the [M-OH]+ and [M-OH-O]+ ions specifically appeared in all spectra of the ortho isomers (I), whereas the para isomers (II) contain [M-O]+ and [M-NO]+ ions. The [M-OH-CO]+ and [M-OH-NO]+ ions in I, and [M-NO2]+ ion in II are the other specific fragment ions observed but feasibility of these fragment ions are found to depend on the nature of the substituent (R). The substitution (-R) effect is also clearly reflected in the formation of fragment ions due to a-cleavage process with or without hydrogen migration. Similar differences in the formation of specific fragment ions are also observed in ortho and para isomers of substituted aryl naphthyl ethers. The methane/CI of isomeric compounds resulted in the same set of fragment ions, but prominent differences are observed in the relative abundance of [MH-NO]+, which is relatively higher in para isomers compared with corresponding ortho isomer.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Substituted Diaryl Ethers; EI Mass Spectra; Specific Fragment Ions; Ortho Effect; Methane Chemical Ionization
ID Code:93633
Deposited On:21 Jun 2012 09:44
Last Modified:21 Jun 2012 09:44

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