TY  - JOUR
AB  - Based on the surprising observation of an intense C4H9+ (m/z 57) peak in the electron impact mass spectrum, the fragmentation of 1,1,2,2,3,3-hexamethylindan (2) was studied by mass-analysed ion kinetic energy Spectrometry of its deuterium-labelled analogues. While methyl loss from ions [2]+ occurs with high selectivity (92%) from the positions 1 and 3 without any rearrangement, ions [2  CH3]+ undergo complete equilibration of the five methyl groups as intact entities. Subsequent multi-step skeletal rearrangement of the [2 - CH3]+ ions leads to formation of tert-butyl ions and to the loss of isobutene and propene, again without concomitant hydrogen exchange. Several kinetic isotope effects and also probably a thermodynamic isotope effect associated with each of these fragmentation processes have been found and their origin is discussed. The possibility of the formation of ion-neutral complexes [t-C4H9+ C10H10] and [s-C3H7+ C11H12] is considered on the basis of the labelling and reactivity pattern.
DA  - 1992
DO  - 10.1002/oms.1210270416
LA  - eng
IS  - 4
M2  - 443
PY  - 1992
SN  - 0030-493X
SP  - 443-452
T2  - Organic Mass Spectrometry
TI  - Unusual fragmentation of 1,1,2,2,3,3-hexamethylindan. Methyl group equilibration and multi-step skeletal rearrangements in the [M - CH3]+ ions prior to the formation of t-C4H9+ and other fragment ions
UR  - https://nbn-resolving.org/urn:nbn:de:0070-pub-17758486
Y2  - 2024-11-22T02:16:38
ER  -