Site-specific hydrogen exchange and hydrogen transfer processes preceding the fragmentation of long-lived radical cations of ethyl dihydrocinnamate and related arylalkanoates
作者:Aaron W. Amick、Edward Hoegg、Sean Harrison、Katelyn R. Houston、Richard R. Hark、I. David Reingold、Dieter Barth、Matthias C. Letzel、Dietmar Kuck
DOI:10.1016/j.ijms.2012.01.005
日期:2012.4
Abstract An electron ionisation study on the fragmentation of metastable molecular radical cations of ethyl 3-phenylpropanoate (ethyl dihydrocinnamate) and related arylalkanoic acid esters was performed by mass-analysed ion kinetic energy (MIKE) spectrometry. Six deuterium-labelled isotopomers of ethyl dihydrocinnamate were synthesised and studied by MIKE spectrometry. The fragmentation leading to ions
摘要 通过质量分析离子动能 (MIKE) 光谱法对 3-苯基丙酸乙酯(二氢肉桂酸乙酯)和相关芳基链烷酸酯的亚稳态分子自由基阳离子的裂解进行了电子电离研究。合成了六种氘标记的二氢肉桂酸乙酯同位素异构体,并通过 MIKE 光谱法进行了研究。在相关二氢肉桂酸烷基酯的 70 eV 质谱图中也观察到了导致离子 C7H7O+ (m/z 107) 的碎片,该过程涉及烷氧基羰基的迁移,但发现它是一个高能量过程,在低亚稳态分子离子的能量。相反,二氢肉桂酸乙酯的亚稳态离子竞争性地失去一氧化碳、乙醇和这些中性碎片的联合损失,从而产生离子化的苯乙烯,C8H8•+ (m/z 104)。发现涉及苄基α-和邻位的四个氢原子的高度特异性H / D交换先于乙醇和[乙醇+ CO]的损失。这代表了完整 4H 的另一个引人注目的案例——扰乱使分子离子在碎裂之前完全平衡交换的氢原子。提出了一种使这些观察结果合理化并扩展先前建议的机