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首页> 外文学位 >Application of Fourier transform ion cyclotron resonance mass spectrometry to reactivity studies of phospheniumions (CIP(+)CI and CH(3)OP(+)OCH(3)) and isomeric 2,3-and 2,5-dihydrofuran radical cations
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Application of Fourier transform ion cyclotron resonance mass spectrometry to reactivity studies of phospheniumions (CIP(+)CI and CH(3)OP(+)OCH(3)) and isomeric 2,3-and 2,5-dihydrofuran radical cations

机译：傅里叶变换离子回旋共振质谱在to离子（CIP（+）CI和CH（3）OP（+）OCH（3））与异构体2,3和2,5-二氢呋喃自由基阳离子反应性研究中的应用

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摘要

Investigations of intrinsic gas-phase reactivity of simple phosphenium ions toward various organic substrates, and the reactivity and thermochemical properties of isomeric 2,3- and 2,5-dihydrofuran radical cations, were carried out by using Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry. The phosphenium ion CIP+CI reacts with selected simple organic substrates via various processes, including addition/elimination, nucleophilic displacement and electron transfer. CIP+CI is extremely reactive and readily cleaves C-H, C-O, C=O, C-N, C-C and N-C(O) bonds. CH3OP +OCH3 was found to be less reactive and to follow different reaction pathways than CIP+CI. This finding is justified by the reaction exothermicity differences between the reactions involving CIP +CI and CH3OP+OCH3. CIP +CI was found to ionize and subsequently induce extensive fragmentation of neutral di- and tripeptides. This was proposed to occur for the dipeptides by elimination of H2O and Cl2P• from the CI2P+/dipeptide adduct. Exact mass measurements, bracketing and H/D exchange experiments, collision-activated dissociation, and molecular orbital calculations were used to characterize the structures of the major product ions generated in the reactions of CIP+CI with dipeptides. Upon reaction with a tripeptide, CIP+CI was found to cleave the two peptides bonds via analogous reaction mechanisms as it cleaves the dipeptides, yielding product ions that contain the intact side chains of two adjacent amino acids. Therefore, CIP+CI produces useful structural information for small peptide. In addition to the phosphenium ion studies, thermochemical properties (e.g., recombination energies) and the reactivity of 2,3- and 2,5-dihydrofuran radical cations were studied. The recombination energies of the 2,3- and 2,5-dihydrofuran radical cations were estimated by bracketing experiments to be 8.4 t 0.2 eV and 8.6 t 0.2 eV. Gas-phase ion-molecule reactions and molecular orbital calculations suggest that isomerization between the 2,3- and 2,5-dihydrofuran radical cations does not occur. However, 2,5-dihydrofuran radical cations likely isomerize to more stable species in the gas phase.
机译：通过使用傅立叶变换离子回旋共振（FT）研究了简单离子对各种有机底物的固有气相反应性以及异构体2,3-和2,5-二氢呋喃自由基阳离子的反应性和热化学性质-ICR）质谱。 ion离子CIP + CI通过各种过程与选定的简单有机底物反应，包括加成/消除，亲核取代和电子转移。 CIP + CI具有极强的反应性，可以轻松裂解C-H，C-O，C = O，C-N，C-C和N-C（O）键。发现CH3OP + OCH3与CIP + CI相比反应性较低，并且遵循不同的反应路径。涉及CIP + CI和CH3OP + OCH3的反应之间的反应放热差异证明了这一发现。发现CIP + CI可以电离并随后引起中性二肽和三肽的大量断裂。对于二肽来说，这是通过从CI2P + /二肽加合物中消除H2O和Cl2P•来实现的。精确的质量测量，包围和H / D交换实验，碰撞活化解离和分子轨道计算被用来表征CIP + CI与二肽反应中生成的主要产物离子的结构。与三肽反应后，发现CIP + CI通过类似的反应机制裂解两个肽键，因为它裂解了二肽，产生了包含两个相邻氨基酸完整侧链的产物离子。因此，CIP + CI为小肽产生有用的结构信息。除了研究ion离子外，还研究了热化学性质（例如重组能）和2，3-和2，5-二氢呋喃自由基阳离子的反应性。通过包围实验估计2，3-和2，5-二氢呋喃自由基阳离子的重组能为8.4 t 0.2 eV和8.6 t 0.2 eV。气相离子分子反应和分子轨道计算表明，2,3-和2,5-二氢呋喃自由基阳离子之间不会发生异构化。然而，2，5-二氢呋喃自由基阳离子可能在气相中异构化为更稳定的物质。

著录项

  • 作者

    Yu, Ying-Qing.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Analytical chemistry.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 169 p.
  • 总页数 169
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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