Characterization by Theory of H-Transfers and Onium Reactions of CH3CH2CH2N+H=CH2

被引：0

作者：

Hudson, Charles E. ^{[1
]}

McAdoo, David J. ^{[1
]}

机构：

[1] Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX, United States

来源：

Journal of the American Society for Mass Spectrometry | 2007年 / 18卷 / 02期

关键词：

H-transfers by 4-; 5-; and 6-membered ring transition states to the π-bonded methylene of CH3CH2CH2NH+=CH2 (1) are characterized by theory and compared with the corresponding transfers in cation radicals. Four-membered ring H-transfers converting 1 to CH3CH2CH=N+HCH3 (2) and CH3N+H=CH2 to CH2=NH+CH3 are high-energy processes involving rotation of the source and destination RHC= groups (R = H or C2H5) to near bisection by skeletal planes; migrating hydrogens move near these planes. The H-transfer 1 &rarr CH3C+HCH2NHCH3 (3) has a higher energy transition-state than 1 &rarr 2; in marked contrast to the corresponding relative energies of 4- and 5-membered ring H-transfers in cation-radicals. Six-membered ring H-transfer-dissociation (1 &rarr CH2=CH2 + CH2=N+HCH3) is a closed shell analog of the McLafferty rearrangement. It has a lower energy transition-state than either 1 &rarr 2 or 1 &rarr 3; but is still a much higher energy process than 6-membered ring H-transfers in aliphatic cation radicals. In contrast to the stepwise McLafferty rearrangement in cation radicals; H-transfer and CC bond breaking are highly synchronous in 1 &rarr CH3N+H=CH2 + CH2=CH2. H-transfers in propene elimination from 1 are ion-neutral complex-mediated:1 &rarr [CH3 CH2 CH2+ - - - NH = CH2] &rarr [CH3 C+ HCH3 NH = CH2] &rarr CH3 CH = CH2 + CH2 = NH2+ . Intrinsic reaction coordinate tracing demonstrated that a slight preference for H-transfer from the methyl containing the carbon from which CH2=NH is cleaved is due to CH2=NH passing nearer this methyl than the other on its way to abstracting H; i.e; some memory of the initial orientation of the partners accompanies this reaction. © 2007 American Society for Mass Spectrometry;

D O I：

暂无

中图分类号：

学科分类号：

摘要：

Journal article (JA)

引用

页码：270 / 278