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首页> 外文期刊>Journal of mass spectrometry: JMS >Dehydrogenation and dehalogenation of amines in MALDI-TOF MS investigated by isotopic labeling
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Dehydrogenation and dehalogenation of amines in MALDI-TOF MS investigated by isotopic labeling

机译：同位素标记法研究MALDI-TOF MS中胺的脱氢和脱卤

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摘要

Secondary and tertiary amines have been reported to form [M-H]+ that correspond to dehydrogenation in matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). In this investigation, we studied the dehydrogenation of amines in MALDI-TOF MS by isotopic labeling. Aliphatic amines were labeled with deuterium on the methylene of an N-benzyl group, which resulted in the formation of [M-D]+ and [M-H]+ ions by dedeuteration and dehydrogenation, respectively. This method revealed the proton that was removed. The spectra of most tertiary amines with an N-benzyl group showed high-intensity [M-D]+ and [M-H]+ ion peaks, whereas those of secondary amines showed low-intensity ion peaks. Ratios between the peak intensities of [M-D]+ and [M-H]+ greater than 1 suggested chemoselective dehydrogenation at the N-benzyl groups. The presence of an electron donor group on the N-benzyl groups enhanced the selectivity. The dehalogenation of amines with an N-(4-halobenzyl) group was also observed alongside dehydrogenation. The amino ions from dehalogenation can undergo second dehydrogenation. These results provide the first direct evidence about the position at which dehydrogenation of an amine occurs and the first example of dehalogenation of haloaromatic compounds in MALDI-TOF MS. These results should be helpful in the structural identification and elucidation of synthetic and natural molecules.
机译：据报道，仲胺和叔胺形成[M-H] +，它对应于基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）中的脱氢。在这项研究中，我们通过同位素标记研究了MALDI-TOF MS中胺的脱氢。脂肪胺在N-苄基的亚甲基上用氘标记，这导致氘和脱氢分别形成[M-D] +和[M-H] +离子。该方法揭示了被除去的质子。具有N-苄基的大多数叔胺的光谱显示高强度[M-D] +和[M-H] +离子峰，而仲胺的光谱显示低强度的离子峰。 [M-D] +和[M-H] +的峰强度之比大于1，表明在N-苄基上发生化学选择性脱氢。 N-苄基上电子供体基团的存在提高了选择性。在脱氢的同时还观察到了具有N-（4-卤代苄基）基团的胺的脱卤。来自脱卤的氨基离子可以进行第二次脱氢。这些结果提供了有关胺脱氢发生位置的第一个直接证据，以及MALDI-TOF MS中卤代芳香族化合物脱卤的第一个例子。这些结果应有助于合成和天然分子的结构鉴定和阐明。

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