Preparation of cyclic N,N'-dimethylureas

摘要

Cyclic N,N'-dimethylureas I <IMAGE> I where A is a 1,2- or 1,3-alkylene group of 2 to 10 carbon atoms, are prepared by reacting the corresponding non-methylated cyclic urea with formaldehyde and excess formic acid and then removing the formic acid still present in the reaction mixture, by a process in which the formic acid is subjected to a thermal decomposition reaction by means of a catalyst system consisting of a tertiary amine and a copper salt.