Premium
Site of gas‐phase methylation of l‐phenyl‐2‐aminopropane
Author(s) -
Zagppey Herman,
Fokkens Roel H.,
Ingemann Steen,
Nibbering Nico M. M.,
Florencio Helena
Publication year - 1991
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210260610
Subject(s) - chemistry , moiety , dissociation (chemistry) , fourier transform ion cyclotron resonance , ion , ring (chemistry) , methyl group , medicinal chemistry , mass spectrometry , stereochemistry , group (periodic table) , organic chemistry , chromatography
The regioselectivity of methyl cation transfer from (CH 3 ) 2 F + , (CH 3 ) 2 Cl + and (CH 3 ) 3 O + to 1‐phenyl‐2‐aminopropane was studied by Fourier transform ion cyclotron resonance in combination with collision‐induced dissociation and neutralization‐reionization mass spectrometry of the stable [M + CH 3 ] + ions formed in a chemical ionization source. The (CH 3 ) 2 F + ion transfers a methyl cation to the NH 2 group and the phenyl ring with almost equal probability. Predominant CH 3 + transfer to the NH 2 group is observed for the (CH 3 ) 2 Cl + ion whereas the (CH 3 ) 3 O + ion reacts almost exclusively at the amino group. The preference for methylation at NH 2 is discussed in terms of a lower methyl cation affinity of the phenyl ring than of the amino group and the existence of an energy barrier for methylation of the phenyl moiety.