Kinetics and Mechanism of Aminolysis of Carbamates

Article abstract of DOI:10.1021/jo00368a020

The kinetics of the n-butylaminolysis of three series of mono- and disubstituted phenyl N-phenylcarbamates 1-3 have been studied spectrophotometrically under pseudo-first-order conditions in dioxane.The relation k_obsd = k₂ + k₃² was found applicable for all esters.The rate constants k₂ and k₃ were correlated by the Hammett equation, and the corresponding activation parameters were determined.The reaction was found to be much more sensitive to a substituent on the leaving group (OAr) than to a substitutent on the amine portion (NHAr) of the esters.Results from crossover experiments revealed the absence of isocyanate intermediate.The mechanism of the aminolysis of carbamates is discussed in terms of these facts.