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The mass spectral behavior of β‐bromoethyl benzoate and some of its ring substituted derivatives: Evidence for oxygen participation in the formation of [M Br] +
Author(s) -
Shapiro Robert H.,
Tomer Kenneth B.
Publication year - 1970
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.1210030308
Subject(s) - chemistry , ethylene , bromine , acetophenone , benzophenone , ring (chemistry) , medicinal chemistry , oxygen , photochemistry , decomposition , fragmentation (computing) , ion , oxygen atom , mass spectrum , organic chemistry , molecule , catalysis , computer science , operating system
The expulsion of a bromine atom from the molecular ion of β‐bromoethyl benzoate displays a kinetic behavior which resembles that of a rearrangement reaction. The two oxygen atoms in the resulting [M Br] + ion become equivalent before or during the secondary decomposition of this ion, as shown by oxygen labeling. In addition, the primary ions generated from benzophenone ethylene ketal and acetophenone ethylene ketal by phenyl and methyl expulsion, respectively, undergo subsequent fragmentation in the same way as the [M Br] + from β‐bromoethyl benzoate. These results strongly indicate that the carbonyl‐oxygen atom participates in the expulsion of bromine. The effect of ring substituents on the competing loss of bromine and McLafferty rearrangement is also discussed.