The hydrolysis of amides, esters, and related compounds in acid solution. Part I. Amides, carbamates, and ureas

Abstract

Studies of the rates of decomposition, in both aqueous perchloric and aqueous sulphuric acids, of ethylurea, ethyl carbamate, and butyramide show that, in spite of the structural similarities, no common mechanism obtains. The comparison reveals that the decomposition of ethyl carbamate shows a change from an A2 to an A1 mechanism with increasing acidity, and that the former is different in kind from that of butyramide. Comparison with methyl carbamate permits some possible mechanisms to be discarded. The rate-determining step in the decomposition of urea and ethylurea involves in both cases the free base at low acidities and the conjugate acid at high acidities. The rate profiles permit evaluation of the acidity constants of the conjugate acids of the two compounds, which are (in water at 100°) 1·1 mole l.^–1 and 0·9 mole l.^–1 respectively.