title: Analysis of diarylmethylamine compounds using electrospray mass spectrometry: formation mechanisms of radical ions and dehydro cations.
abstract: A series of diarylmethylamine compounds were analyzed using electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF-MS). [M](+)˙ and [M - H](+) were both observed, but showed different abundances. A possible mechanism for the formation of [M](+)˙ and [M - H](+) was proposed to explicate the rule for the ratio change of I([M](+)˙)/I([M-H](+)). The [M](+)˙ has two structures, which can interconvert into each other in the gas phase. The substituted groups on the benzene rings play a crucial role in the transfer between the two structures. Electron withdrawing groups can prevent the formation of carbocations, thus nitro-containing diarylmethylamines remained mainly as structure I and were detected as [M](+)˙. On the contrary, electron donating groups help to stabilize carbocations. This makes structure I transfer to structure II, and structure II prefers to further generate [M - H](+) by loss of an H radical. Nuclear magnetic resonance and D-labelled MS experiments indicate that the 1-C-H bond has strong activity.
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China. wuzj@cib.ac.cn.
authors.forename: Tian
authors.initials: T
authors.lastname: Cai
authors.forename: Xiao-Ying
authors.initials: XY
authors.lastname: Xu
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Wu
mesh_terms: D002412:Cations / Q000737:chemistry; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D005609:Free Radicals / Q000737:chemistry*; D008744:Methylamines / Q000032:analysis* / Q000737:chemistry; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D002412:Cations; D005609:Free Radicals; D008744:Methylamines; C027451:methylamine