Low-energy collision-induced fragmentation of negative ions derived fromortho-,meta-, andpara-hydroxyphenyl carbaldehydes, ketones, and related compounds
作者:Athula B. Attygalle、Josef Ruzicka、Deepu Varughese、Jason B. Bialecki、Sayed Jafri
DOI:10.1002/jms.1252
日期:2007.9
2-hydroxy-1-naphthaldehyde, both of which show two consecutive CO eliminations, specifically lose the carbonyl oxygen first, followed by that of the phenolic group. Anions from 2-hydroxyphenyl alkyl ketones lose a ketene by a hydrogen transfer predominantly from the alpha position. Interestingly, a very significant charge-remote 1,4-elimination of a H(2) molecule was observed from the anion derived from 2,4-dihydroxybenzaldehyde
记录了几种羟基苯基甲醛和酮产生的阴离子的碰撞诱导解离(CID)质谱,并进行了机械合理化。例如,去质子化的邻羟基苯甲醛的m / z 121离子光谱在m / z 93处显示一个强烈的峰,表明一氧化碳的损失归因于由电荷定向的杂化断裂机制介导的邻位效应。相反,衍生自间位和对位异构体的m / z 121离子经过电荷远程均质裂解以消除* H并形成distonic阴离子自由基,最终使CO丢失,从而在m / z 92处出现一个峰。对于对位异构体,这种两步均质机制是最主要的片段化途径。另一方面,间位异构体的光谱 图1b显示了分别在m / z 92和93处的两个主要峰,分别代表了同质和异质碎片。(18)O-同位素标记研究证实,从间羟基苯甲醛的阴离子中消除的CO分子中的氧源自醛基或酚基。相反,邻羟基苯甲醛和2-羟基-1-萘醛的阴离子,都显示出连续的两次CO消除,首先是先失去羰基氧,然后才失去酚基团的羰基氧。