TY  - JOUR
AB  - Loss of isobutane is the exclusive fragmentation channel of long-lived protonated tert-butyl-substituted alpha,omega-diphenylalkanes with chain lengths n = 2-12. Methane chemical ionization/mass-analysed ion kinetic energy spectrometry of the [M + H]+ ions and several deuterium-labelled tert-butyl-substituted 1,2-, 1,3- and 1,10-diphenylalkanes revealed that the reaction involves with equal probability and maximum regioselectivity a hydride ion from both the adjacent and the remote benzylic methylene groups, irrespective of the length of the aliphatic chain. The isotope effect of the hydride abstraction step was found to be same in all cases, k[C4H10]/k[C4H9D] = 1.6 +/- 0.1. A sterically restricted system, protonated 1-benzyl-4-(tert-butylbenzyl)benzene, shows the same behaviour. This implies, as a general phenomenon, the formation of intermediate ion-neutral complexes [C4H9+ Ar(CH2)(n)Ar] along with (or instead of) the corresponding pi complexes [C4H9+...Ar(CH2)(n)Ar] prior to isobutane elimination (Ar represents a phenyl or substituted-phenyl group).
DA  - 1993
DO  - 10.1002/oms.1210281016
LA  - eng
IS  - 10
M2  - 1073
PY  - 1993
SN  - 0030-493X
SP  - 1073-1081
T2  - Organic Mass Spectrometry
TI  - Intermediate ion-neutral complexes formed during the gas-phase protonolysis of p-(tert-butyl)-substituted alpha,omega-diphenylalkanes
UR  - https://nbn-resolving.org/urn:nbn:de:0070-pub-17742058
Y2  - 2024-11-22T05:12:00
ER  -