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Relative stabilities of the methyltropylium and α‐phenylethyl cations
Author(s) -
Barbalas Michael P.,
McLafferty Fred W.
Publication year - 1982
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.1210171210
Subject(s) - ion , photoionization , chemistry , metastability , dissociation (chemistry) , isomerization , yield (engineering) , decomposition , ethylbenzene , collision induced dissociation , mass spectrometry , photochemistry , toluene , analytical chemistry (journal) , tandem mass spectrometry , ionization , organic chemistry , materials science , chromatography , metallurgy , catalysis
Metastable decomposition of ethylbenzene molecular ions should yield [C 8 H 9 ] + ions of nearly threshold energies. Mass spectral data from collisionally activated dissociation of these ions show them to be mainly the methyltropylium ( a ) isomer, which is also that formed from 7‐methylcycloheptatriene and isopropylbenzene. Combined with the threshold photoionization studies of McLoughlin, Morrison and Traeger, this establishes a as the most stable [C 8 H 9 ] + isomer. This is more stable than the α‐phenylethyl isomer ( b ), which can be formed from α‐bromoethylbenzene molecular ions; higher energy b ions appear to isomerize to a .