Metastable ion and induced stable ion fragmentation of isomeric 5-methyl-3-tolyl-1,2,4-oxadiazoles |
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Authors: | Lawrence T Nielsen R M Srivastava Lຽda M M e Silva |
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Institution: | Lawrence T. Nielsen,R. M. Srivastava,Lẽda M. M. e Silva |
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Abstract: | The electron ionization fragmentation patterns of 5-methyl-3-(o-, m- and p-tolyl)-1,2,4-oxadiazoles (1a—c) have been examined by metastable ion and high resolution mass spectrometry. The o-tolyl isomer loses CO and C2H2O from the metastable molecular ion whereas the m- and p-tolyl isomers lose only CH3CN thus indicating a strong ortho effect in directing the fragmentation in 1a. Slight differences between o-, m- and p-tolyl isomers in the collisional activation fragmentation of stable C7H6N]+ ions suggest that structural differences exist even after a series of extensive rearrangements of the molecular ions. Metastable ion kinetic energy (MIKE) and collisional activation (CA) spectra were very helpful in providing valuable information about many fragments. |
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