Substitution reactions in ionic liquids. A kinetic study
作者:Bradley Y.W. Man、James M. Hook、Jason B. Harper
DOI:10.1016/j.tetlet.2005.08.064
日期:2005.10
The rate of the substitution reaction of (R)-3-chloro-3,7-dimethyloctane (1) with either methanol or benzyl alcohol in mixtures containing the ionic liquid [Bmim][N(CF3SO2)2] was monitored using 35Cl NMR spectroscopy. The enantiomeric excess of the product, (S)-3-methoxy-3,7-dimethyloctane (2a), was analyzed using chiral gas chromatography. This product showed a decreasing enantiomeric excess with
监测(R)-3-氯-3,7-二甲基辛烷(1)与甲醇或苯甲醇在含离子液体[Bmim] [N(CF 3 SO 2)2 ]的混合物中的取代反应速率使用35 Cl NMR光谱法。使用手性气相色谱分析产物(S)-3-甲氧基-3,7-二甲基辛烷(2a)的对映体过量。随着离子液体浓度的增加,该产物显示出减少的对映体过量。底物1的反应速率在每种情况下,随离子液体的浓度而变化。通过标准方法进行溶剂混合物的极性测量,将它们相互比较并与观察到的速率进行比较。还建议分别进行溶剂重组和选择性溶剂化,以促进观察到的反应速率的差异。
Gas-phase stability of tertiary carbenium ions and rates of solvolysis of tertiary derivatives
作者:Paul M�ller、Jean-Claude Rossier、Jose-Luis M. Abboud
The stability of tertiary carbenium ions was determined in the gas phase by ion cyclotron resonance (ICR) and by dissociative proton attachment (DPA). The rate constants for solvolysis of bridgehead derivatives correlate well with the stabilities of bridgehead carbenium ions, as determined by DPA and by ICR, but the ICR data of strained ions do not correlate, indicating rearrangements under the conditions