Mechanistic studies in the chemistry of urea. Part 2. Reaction with benzil, 4,4′-dimethylbenzil, and 4,4′-dimethoxybenzil

Abstract

Urea and N-methylurea react with benzil and substituted benzils in alkaline conditions to form 5,5-diphenylhydantoins, or the appropriately substituted compounds. The mechanism of reaction is rate-determining attack by the urea anion on benzil, rapid cyclisation, and slow rearrangement. The mechanism was deduced from a kinetic study, With NN′-dimethylurea the product is a diol.