An improved process for preparing triethylenemelamine from ethylenimine and cyanuric chloride has been developed. It features the use of an aqueous reaction medium and the generation of ethylenimine in solution, which obviates the isolation and handling of anhydrous ethylenimine. The rates of formation of ethylenimine from 2-aminoethyl hydrogen sulfate, 2-chloroethylamine hydrochloride, and 2-bromoethylamine hydrobromide have ...