Stabilities and structures in cluster ions of five-membered heterocyclic compounds containing oxygen, nitrogen, and sulfur atoms
作者:K. Hiraoka、H. Takimoto、S. Yamabe
DOI:10.1021/ja00258a018
日期:1987.11
radical cations of heterocyclic compounds, e.g., furan, tetrahydrofuran, pyrrole, pyrrolidine, thiophene, and tetrahydrothiophene, have been studied using a pulsed electron beam mass spectrometer. The bond energies of proton-held dimer cations for furan, pyrrole, and thiophene are much smaller than those for tetrahydrofuran, pyrrolidine, and tetrahydrothiophene, respectively. This result suggests that not
已经使用脉冲电子束质谱仪研究了杂环化合物(例如呋喃、四氢呋喃、吡咯、吡咯烷、噻吩和四氢噻吩)的质子化和自由基阳离子的聚类和水合反应。呋喃、吡咯和噻吩的质子保持二聚体阳离子的键能分别比四氢呋喃、吡咯烷和四氢噻吩的键能小得多。该结果表明,呋喃、吡咯和噻吩的质子化不是杂原子而是 ..cap α.. 碳原子。质子化呋喃和噻吩的氢键位点计算为未质子化的 ..cap alpha.. 氢(CH/sub ..cap alpha../ 与杂原子相邻),它是酸性最强的。另一方面,NH 氢是质子化吡咯的最佳氢键位点。发现自由基阳离子二聚体比呋喃和噻吩的质子保持二聚体阳离子具有更大的键能。这表明前者的键具有更多的共价性质。观察到 C/sub 4/H/sub 4/O/sup .+/ 和 C/sub 4/H/sub 5/O/sup +/ 与呋喃分子的一些独特反应。随着温度升高,m/z 离子与 (C/sub 4/H/sub