Collision-Induced Dissociation (CID) Spectra versus Collision Energy Using a Quadrupole Ion Trap Mass Spectrometer IV --Dissociation of Ionized Maleamide and Fumaramide--

摘要

The unimolecular decompositions of the geometrical isomers maleamide (cis-NH_2COCH = CHCONH_2; 1, MW: 114) and fumaramide (trans-NH_2COCH = CHCONH_2; 2, MW: 114) have been investigated by use of collision-induced dissociation (CID) spectra versus collision energy. These ions, 1~(+ centre dot) and 2~(+ centre dot), show as primary fragmentation channels the losses of NH_2 and CONH to give the ions m/z 98 and 71, respectively, but the relative abundance of these ions is different with each other. Thiswill be attributable to amide-amide interaction in cis-isomer. The fragment ions m/z 71 correspond to the molecular ion of acrylamide, CH_2 = CHCONH_2, which is formed by hydrogen atom migration from NH_2 to ethylenic carbon in the molecular ions 1~(+ centre dot) and 2~(+ centre dot), followed by CONH loss. The additional dissociation channels are observed for 2~(+ centre dot), the losses CO and CONH_2 to give the ions at m/z 86 and 70, respectively. These two reactions were weak for 1~(+ centre dot). These ions, except for m/z 71 ion, retain the structure difference between the geometrical isomers. The [M -- NH_2]~+ ions decompose further by the losses of H_2O and CO to generate the ions at m/z 80 and 70, respectively. The former reaction for 1 is different from that for 2. This reaction accompanies with double hydrogen atom transfers, and was not described in previous report.