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Formation of 2‐substituted benzofuran fragment ions from 6‐alkyl‐ and 6‐aryldibenzo( d,f )(1,3)dioxepine derivatives under electron ionization—a useful precursor ion for isomeric differentiation
Author(s) -
Begala Michela,
Tocco Graziella,
Meli Gabriele,
Podda Gianni,
Urru Silvana A. M.
Publication year - 2009
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1503
Subject(s) - chemistry , furan , fragmentation (computing) , electron ionization , ion , isomerization , mass spectrum , tandem mass spectrometry , mass spectrometry , dissociation (chemistry) , medicinal chemistry , collision induced dissociation , stereochemistry , ionization , organic chemistry , chromatography , computer science , catalysis , operating system
Tandem mass spectrometry has been applied to differentiate three sets of o ‐, m ‐ and p ‐methyl, ‐methoxy and ‐nitro‐substituted‐6‐phenyl‐dibenzo( d,f )(1,3)dioxepines. Collision‐induced dissociation (CID) experiments have been carried out on 2‐phenylbenzo[ b ]furan fragment ions, which originate from the decomposition of the molecular ions after their EI‐induced isomerization to spirocyclic structures. With the exception of m ‐ and p ‐methylphenylbenzo[ b ]furan isomers, which display identical CID mass spectra, the three isomeric methoxy‐ and nitrophenylbenzo[ b ]furan fragment ions display very characteristic CID behavior which allows unequivocal differentiation of the 6‐phenyl‐dibenzo( d,f )(1,3)dioxepine isomers. 6‐( o ‐nitrophenyl)‐dibenzo( d,f )(1,3)dioxepine isomer, does not form a 2‐( o ‐nitrophenyl)benzo[ b ]furan ion and, therefore, it can be differentiated from the m ‐ and p ‐ isomers based on the mere EI mass spectra. Furthermore, it shows a characteristic ion most likely due to an ortho effect between the nitro group and the dioxepine ring. Multiple stage mass spectrometric techniques (MS n ), labeled derivatives and reference compounds were used in order to gain additional information on the structures of product ion from the CID fragmentation. Copyright © 2008 John Wiley & Sons, Ltd.