The hydrolysis of amides, esters, and related compounds in acid solution. Part III. Ureas

Abstract

The kinetics of hydrolysis at 99·5 °C of urea, NNN′N′-tetramethylurea, and O-methylisourea in aqueous sulphuric and methanesulphonic acids have been studied. In solutions of intermediate acidity the three substrates share a common mechanism of hydrolysis, believed to be a bimolecular reaction between water and the diprotonated urea. At lower acidities a demethylation reaction, with alkyl–oxygen fission, intrudes with O-methylisourea, and the mode of decomposition of urea changes to the well known unimolecular decomposition of the free base. In highly concentrated sulphuric acid, urea only is thought to undergo sulphonation before decomposition.