Ion–neutral–neutral complexes in unimolecular reactions: formation of proton-bound alkanol pairs from alkoxylated oxonium ions
作者:Ya-Ping Tu、John L. Holmes
DOI:10.1039/b101287h
日期:——
The proton-bound alkanol pairs, [ROHââ¯âH+ââ¯âRâ²OH], were generated in the unimolecular fragmentation reactions of alkoxylated oxonium ions ROCH2âO+(Râ²)(Râ³) (where R, Râ²Â = CH3 or C2H5; Râ³Â = t- or iC4H9). By means of collision-induced dissociative ionization mass spectrometry, the neutral counterpart of this reaction was identified to be a C5H8 hydrocarbon molecule. It is proposed that the reactions proceed through an intermediate ionâneutral complex in which two neutral alkanol molecules are associated with the 1,1-dimethylallyl cation, CH2CHâC+(CH3)2; the subsequent proton transfer leads to the formation of the proton-bound alkanol pair and neutral 2-methylbuta-1,3-diene (C5H8).
This is the first three-component intermediate âionâneutralâneutralâ complex (where the ion is not a proton) identified in the unimolecular fragmentation of covalently-bonded organic ions in the gas phase.
质子结合的烷醇对,[ROH–––H+–––R–2OH],是在烷氧基化氧鎓离子 ROCH2–O+(R–) 的单分子裂解反应中生成的。 2)(R–3)(其中 R、R–2=CH3 或 C2H5;R–3=t- 或 iC4H9)。通过碰撞诱导解离电离质谱分析,该反应的中性对应物被鉴定为C5H8碳氢化合物分子。据推测,反应通过中间离子-中性络合物进行,其中两个中性烷醇分子与 1,1-二甲基烯丙基阳离子 CH2CH-C+(CH3)2 缔合;随后的质子转移导致质子结合的烷醇对和中性的 2-甲基丁-1,3-二烯 (C5H8) 的形成。
这是在气相中共价键有机离子的单分子裂解中鉴定出的第一个三组分中间体“离子”“中性”“中性”络合物(其中离子不是质子)。