MECHANISM OF BASE CATALYSIS IN THE REACTIONS OF PHENYL ARYL ETHERS WITH ALIPHATIC-AMINES IN DIMETHYL-SULFOXIDE

The reactions of n-butylamine, pyrrolidine and piperidine with phenyl 2,4,6-trinitrophenyl ether, 3, in DMSO result in the rapid reversible formation of adducts by reaction at the 3-position followed by attack at the 1-position leading to substitution of the phenoxy group. With p henyl 2,4-dinitronaphthyl ether, 1a, and phenyl 2,4-dinitrophenyl ethe r, 8, substitution is the only process observed. For each substrate re actions with n-butylamine show a first order dependence on the amine c oncentration indicating that nucleophilic attack is rate-limiting. How ever, the reactions with pyrrolidine and with piperidine are subject t o general base catalysis and-it is argued that here the deprotonation of the initially formed zwitterionic intermediates is rate determining . The results are compared and contrasted with those of the correspond ing ethyl ethers, where base:catalysis involves the SB-GA mechanism, a nd with phenyl sulfides.