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Gas‐phase derivatization of [C 3 H 5 ] + ions using tandem mass spectrometry methods A 13 C labelling study
Author(s) -
My Nguyen Kieu,
Schilling Marita,
Schwarz Helmut
Publication year - 1987
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.1210220506
Subject(s) - chemistry , protonation , derivatization , allyl bromide , propenyl , medicinal chemistry , benzene , mass spectrometry , bromide , ion , tandem mass spectrometry , heterolysis , chemical ionization , photochemistry , ionization , inorganic chemistry , organic chemistry , chromatography , catalysis
The study of specifically 13 C‐labelled precursors sheds further light on the gas‐phase chemistry of allyl and 2‐propenyl cations. It is demonstrated that both species are formed from allyl and 2‐propenyl bromide upon 70 eV electron impact ionization without skeletal reorganization. Gas‐phase derivatization of the [C 3 H 5 ] + ions with benzene facilitates, as suggested and observed earlier, the distinction of the two isomers using collision‐induced dissociation of the Wheland complexes (or isomers thereof). The 13 C labelling data clearly demonstrate that 64% of allyl cations survive the derivatization while 36% isomerize to 2‐phenylpropyl cations; the latter are also formed via the reaction of 2‐propenyl cation with benzene, protonation of α‐methylstyrene and water loss from protonated 2‐phenyl‐2‐propanol, respectively. Unimolecular loss of C 2 H 4 from protonated allylbenzene proceeds via two competing reaction channels: one involves heterolysis of 1‐phenylpropyl cations (∼30%); the major pathway (∼70%), however, involves decomposition via propylene benzenium ions.