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Ion–molecule reactions in the gas phase. Collision energy influence on the competitive S N i/S N 2 orientation from adduct ions of epimeric 1,2‐indanediols prepared by ammonia chemical ionization
Author(s) -
Bourhis C.,
Perlat M. C.,
Fournier F.,
Tabet J. C.
Publication year - 1997
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(199711)11:17<1839::aid-rcm48>3.0.co;2-#
Subject(s) - chemistry , ion , gas phase , adduct , molecule , collision , orientation (vector space) , computational chemistry , analytical chemistry (journal) , organic chemistry , geometry , computer security , mathematics , computer science
Under chemical ionization (CI) conditions, cis and trans 1,2‐indanediols mainly react with the NH 3 /NH 4 + system via a nucleophilic substitution process. In the CI source several mechanisms can occur yielding the substituted [M + NH 4 − H 2 O] + ions at m/z 150. Collisionally activated reaction (CAR) spectra provide additional information concerning the structure of selected low kinetic energy species. These ion–molecule reactions with methylamine are performed for [M + NH 4 − H 2 O] + ions in the collision cell of a triple quadrupole mass spectrometer. In this way, the nucleophilic substitution process is demonstrated to depend on the stereochemistry of the indanediol precursor. Stereospecific S N 2 and S N i pathways operate for the cis and trans derivatives, respectively. Such competitive orientations are explained by considering hydrogen bonds and the steric hindrance due to the homobenzylic group. © 1997 John Wiley & Sons, Ltd.