کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1194316 | 1492394 | 2006 | 8 صفحه PDF | دانلود رایگان |
The fragmentation of the 2,3-pentanedione radical cation gives rise to an unexpected composite metastable ion peak, m/z 72, resulting from the isobaric losses of CO and C2H4. These two fragmentation channels are energetically competitive (i.e., the transition states have similar energies). The two processes yield [CH3C(O)CH2CH3]+ and [CH3C(OH)CO]+, respectively. The latter new ion, which is produced by a McLafferty rearrangement, has ΔfH° = 604 kJ/mol, obtained from G3 calculations. The four competing processes for metastable [CH3COCOCH2CH3]+, the (intense) losses of CH3CO, CH3CH2CO and the weak losses of C2H4 and CO and their transition states were placed on a potential energy surface computed at the G3 level of theory. The homologous ionized diketone 2,3-butanedione also displays the decarbonylation channel and 3,4-hexanedione loses CO and C2H4.
Journal: International Journal of Mass Spectrometry - Volumes 249–250, 1 March 2006, Pages 222–229