Open AccessAbsolute assignment of constitutional isomers via structurally diagnostic fragment ions: The challenging case of α- and β-acyl naphthalenes
Author(s) -
Mario Benassi,
Marcos N. Eberlin
Publication year - 2010
Publication title -
journal of the american society for mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.961
H-Index - 127
eISSN - 1879-1123
pISSN - 1044-0305
DOI - 10.1016/j.jasms.2010.08.019
Subject(s) - chemistry , thioether , structural isomer , molecule , ether , propionitrile , ion , mass spectrometry , methyl vinyl ketone , acetonitrile , medicinal chemistry , stereochemistry , organic chemistry , chromatography , catalysis
A general mass spectrometric method is described for the absolute assignment of α- or β-acyl naphthalenes, via which the gaseous α- and β-naphthoyl cations of m/z 155 are used as structurally diagnostic fragment ions (SDFI). These stable acylium ions are common and normally abundant fragment ions of acylnaphthalenes in general. Using a pentaquadrupole mass spectrometer, CID experiments with argon and ion/molecule reactions with 2-methyl-1,3-dioxolane, isoprene, acetonitrile and propionitrile were performed but failed to distinguish the two SDFI. Reactions with ethyl vinyl ether and several homologues as well as ethyl vinyl thioether were, however, successful. In reactions with ethyl vinyl ether, the α-SDFI form a pair of diagnostic product ions of m/z 165 and m/z 181, which are absent in the corresponding spectrum of the β-SDFI. Methyl 4-(1-naphthyl)-2,4-dioxobutanoate was used as a test molecule for this class of constitutional isomers and absolute structural assignment as an α-acyl naphthalene was correctly performed via the characterization of its α-SDFI.