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Fragmentation selectivity in electron impact ionization mass spectra of substituted dimethoxybenzenes
Author(s) -
Nakata Hisao,
Jitsukawa Fumie,
Toyama Hitomi,
Kato Yuko
Publication year - 1992
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210270613
Subject(s) - electron ionization , fragmentation (computing) , substituent , chemistry , mass spectrum , ionization , ion , halogen , selectivity , spectral line , electron , analytical chemistry (journal) , medicinal chemistry , organic chemistry , physics , alkyl , quantum mechanics , astronomy , computer science , catalysis , operating system
Several 1‐X‐sabstitirted‐3‐methoxy‐4‐trideuteromethoxybenzens were synthesized and their electron impact ionization mass spectra were measured with an ionizing energy of 20 eV. From the peak intensity ratio of [M CD 3 ] and [M CH 3 ] the fragmentation‐directing ability of the substituent X was evaluated. The most powerful group was found to be NH 2 , which expelled a methoxy methyl group only from its para position. The CH 3 group and four halogen atoms, F, Cl, Br and I, exerted a moderate effect Electron‐withdrawing groups such as NO 2 , CHO and CN had only a little influence on the fragmentation selectivity. These results were interpreted in terms of the effect of X on the distribution of both the unpaired electron and the positive charge in the molecular ion.