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The [M − 1 ]+ quasi-molecular ion in chemical ionization mass spectrometry. Fragmentation of bis(benzyloxy)silanes by intramolecular reactions


Bild, Norbert; Chapeaurouge, Alexander; Gfeller, Stefan; Bienz, Stefan (1992). The [M − 1 ]+ quasi-molecular ion in chemical ionization mass spectrometry. Fragmentation of bis(benzyloxy)silanes by intramolecular reactions. Journal of Mass Spectrometry, 27(8):896-900.

Abstract

The unusual chemical ionization mass spectrometric behavior of bis(benzyloxy)silanes showing heavy fragmentation and an [M − 1]+ fragment, instead of the expected [M + 1]+ ion with isobutane as the reactant gas, was investigated by means of (chloromethyl)bis(benzyloxy)methylsilane and model compounds. It could be shown that probably an intramolecular hydride transfer to an adjacent proton via a six-membered transition state gives rise to the uncommon [M − 1]+ quasi-molecular ion. Similar intramolecular reactions transferring a hydride, a chloro-methyl, a phenyl or a benzyl group via cyclic transition states to a neighboring electrophile are held responsible for five of the six additional major fragments. The results demonstrate that fragmentation reactions become important in chemical ionization mass spectrometry if a molecule or an initially formed cluster ion possesses reactive groups which are in close proximity to each other.

Abstract

The unusual chemical ionization mass spectrometric behavior of bis(benzyloxy)silanes showing heavy fragmentation and an [M − 1]+ fragment, instead of the expected [M + 1]+ ion with isobutane as the reactant gas, was investigated by means of (chloromethyl)bis(benzyloxy)methylsilane and model compounds. It could be shown that probably an intramolecular hydride transfer to an adjacent proton via a six-membered transition state gives rise to the uncommon [M − 1]+ quasi-molecular ion. Similar intramolecular reactions transferring a hydride, a chloro-methyl, a phenyl or a benzyl group via cyclic transition states to a neighboring electrophile are held responsible for five of the six additional major fragments. The results demonstrate that fragmentation reactions become important in chemical ionization mass spectrometry if a molecule or an initially formed cluster ion possesses reactive groups which are in close proximity to each other.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:1992
Deposited On:31 Oct 2017 16:28
Last Modified:09 Dec 2017 03:08
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:1076-5174
Publisher DOI:https://doi.org/10.1002/oms.1210270809

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