TY  - JOUR
AB  - Gaseous benzenium C6H7+(1) and toluenium C7H9+(2) ions have been generated by mass spectrometric loss of CO2H from the corresponding 1,4-dihydrobenzoic acids (3) and (4), and their fragmentations after ca. 10 µs have been investigated by means of mass-analysed ion kinetic energy (MIKE) spectrometry of some 2H and 13C labelled analogues. Metastable C6H7+ ions eliminate H2 after proton randomization, whereas metastable C7H9+ ions expel both H2 and CH4 after incomplete proton equilibration. In particular, 40% of C7H9+ ions randomize all their carbon and hydrogen atoms prior to loss of CH4, and 60% of C7H9+ ions lose the original methyl group along with a hydrogen atom from the (proton-equilibrated) benzenium ring, accompanied by a slow and incomplete exchange between the hydrogen atoms of the ring and the methyl group. It is suggested that loss of both CH4 and H2 occur via the (ipso-)toluenium ion (2). The role of a non-classical C7H9+ isomer, phenylmethonium ion (6), is discussed since striking similarities are found compared with [C6H6·CH3+]* adducts from ion–molecule reactions described in the literature.
DA  - 1985
DO  - 10.1039/P29850000689
LA  - eng
IS  - 5
M2  - 689
PY  - 1985
SN  - 0300-9580
SP  - 689-696
T2  - Journal of the Chemical Society, Perkin Transactions 2, Physical Organic Chemistry
TI  - A study of gaseous benzenium and toluenium ions generated from 1,4- dihydro- and 1-methyl-1,4-dihydro-benzoic acids
UR  - https://nbn-resolving.org/urn:nbn:de:0070-pub-17743098
Y2  - 2024-11-22T11:29:01
ER  -