Kinetics of the reaction of guanyl-O-methylisourea hydrochloride with dimethylformamide dimethylacetal

Abstract

The reaction of guanyl-O-methylisourea hydrochloride (IV) with dimethylformamide (V) proceeds in two steps. The first step consists in the reaction of the imidoester with the imidatonium ion formed in a fast pre-equilibrium to give a conjugated system with the absorption maximum at 278 nm. The subsequent slower step consists in the cyclization to 2-amino-4-methoxy-1,3,5-triazine (VI). The rate of the first step is directly proportional to the concentrations of both hydrochloride IV and acetal V. Both the steps involve base catalysis. Mechanism of the whole reaction is suggested on the basis of the kinetic results.