Differential metal ion stabilization of reactants and transition states in the transacylation of crown ether aryl acetates
作者:Roberta Cacciapaglia、Arie R. Van Doorn、Luigi Mandolini、David N. Reinhoudt、Willem Verboom
DOI:10.1021/ja00033a038
日期:1992.3
Transfer to methoxide ion of the acetyl group of a series of crown ether aryl acetates ranging from 2-AcO-15C4 to 2-AcO-27C8 is accelerated by alkali and alkaline earth metal ions. The magnitude of the rate enhancements is dependent on the substrate-cation combination, the divalent metals being in general much stronger catalysts than the monovalent metals. A maximum catalytic effect of 760 is observed
碱金属和碱土金属离子加速了一系列冠醚芳基乙酸酯的乙酰基向甲醇离子的转移,范围从 2-AcO-15C4 到 2-AcO-27C8。速率提高的幅度取决于底物-阳离子组合,二价金属通常比一价金属强得多的催化剂。在 Ba 2+ 催化的 2-AcO-18C5 反应中观察到的最大催化效果为 760