NEGATIVE ION CHEMICAL IONIZATION MASS SPECTROMETRY OF PERFLUOROACYL DERIVATIVES

用负离子化学电离（NCI）质谱法测定了其结构。 五氟丙酰基（PFP）和七氟丁酰基（HFB）衍生物 2-氨基苯酚含有一种碱离子， 包括44 amu的A损失，并且反映这种损失的离子也被 在其他化合物的PFP或HFB衍生物的NCI光谱中观察到， 邻羟基苯胺类，包括3-羟基联苯胺和正丙基 2-羟基苯胺酸和2-氨基酪氨酸的酯。 相应的 在三氟乙酰基（TFA）的NCI光谱中未观察到离子 2-氨基苯酚的衍生物或PFP或HFB光谱中 羟基苯胺的Meta或帕拉异构体的衍生物或 2-乙氨基苯酚。 研究这种损失的机制， 串联质谱法、链接扫描和高分辨率质谱 光谱分析显示，它反映了CO2的消除，并表明 碎片化途径涉及HF的初始损失， 氢原子的来源 衍生的酰胺氮，然后形成环 中间体，随后从该中间体中除去CO2以产生 另一个环形结构。 由44 amu的损失产生的离子也被 在儿茶酚的HFB或PFP衍生物的NCI光谱中观察到， 包括左旋多巴和儿茶酚本身，以及这种损失的机制 还可能涉及形成环中间体， 随后被淘汰。 这种CO2损失的发生可能是 用于区分羟基苯胺的区域异构体， 以区分邻苯二酚与间苯二酚或对苯二酚核。

The negative ion chemical ionization (NCI) mass spectra of the pentafluoroproprionyl (PFP) and heptafluorobutyryl (HFB) derivatives of 2-aminophenol contain a base ion which is generated by a mechanism involving the a loss of 44 amu, and ions reflecting this loss are also observed in the NCI spectra of the PFP or HFB derivatives of other ortho hydroxyanilines, including 3-hydroxybenzidine and the n-propyl esters of 2-hydroxyanilinic acid and 2-aminotyrosine. A corresponding ion is not observed in the NCI spectra of the trifluoroacetyl (TFA) derivative of 2-aminophenol or in the spectra of the PFP or HFB derivatives of meta or para isomers of hydroxyaniline or of 2-ethylaminophenol. Examination of the mechanism of this loss by tandem mass spectrometry, linked scanning, and high resolution mass spectrometry revealed that it reflects elimination of CO2 and indicate that the fragmentation pathway involves an initial loss of HF, in which the hydrogen atom is derived from the deriv atized amide nitrogen, followed by formation of a ring intermediate from which CO2 is subsequently eliminated to yield another ring structure. An ion generated by loss of 44 amu is also observed in the NCI spectra of HFB or PFP derivatives of catechols, including L-dopa and catechol itself, and the mechanism of this loss may also involve formation of a ring intermediate from which CO2 is subsequently eliminated. The occurrence of this loss of CO2 can be used to achieve distinction among regio-isomers of hydoxyanilines and to distinguish a catechol from a resorcinol or hydroquinone nucleus.