Acylation. Part XXXI. Preferred transition states for ester aminolysis in non-hydroxylic solvents

Abstract

In diethyl ether solution, at 25°, triethylenediamine is as an effective catalyst in the n-butylaminolysis of esters as is a second molecule of n-butylamine, and is at least 45-fold more effective than is triethylamine. In 1 : 1-adduct formation with acetic acid under similar conditions the equilibrium constant has the value 72, 20, and 12 l. mole^–1 respectively for n-butylamine, triethylenediamine, and triethylamine. The relative basicities are very different from those obtained for aqueous solution. Present and previous results suggest that triethylenediamine operates via nucleophilic catalysis, and that, for primary amines, cyclic transition states are greatly preferred to those involving simple proton abstraction by the catalysing base.