Effect of Cation-Complexing Agents on the Ba(II)-Assisted Basic Ethanolysis of Phenyl Acetate: From Cation Deactivation to Cation Activation.
A thorough investigation of the effect of adding cation complexing agents on the barium-assisted basic ethanolysis of phenyl acetate shows that any catalytic activity disappears upon sequestration of the metal ion by cryptand 222, but addition of the crown ethers 18C6, 15C5, and 12C4 yields ternary complexes of 1:1:1 (crown ether)-(metal ion)-ethoxide composition, in which instead of the expected cation deactivation a definite cation activation takes place. Clear-cut evidence was obtained that the quaternary complex [EtOBa(15C5)(2)](+), albeit substantially less reactive than the uncomplexed barium-bound ethoxide, is still more reactive than free ethoxide.
Cacciapaglia
Roberta
R
Centro CNR di Studio sui Meccanismi di Reazione and Dipartimento di Chimica, Università La Sapienza, 00185 Roma, Italy.
Mandolini
Luigi
L
Castelli
Valeria Van Axel
VV