Curable mixtures containing epoxy resins and isomelamines

A novel process for the preparation of isomelamines of the formula I, (I) which is characterized in that an N-cyano-N-(ar or cyclo)alkylcarboxylic acid amide or N-cyano-N-allylcarboxylic acid amide of the formula II or III is reacted with aqueous sodium hydroxide solution, potassium hydroxide solution or ammonia solution or a primary aliphatic or cycloaliphatic amine in a solvent or with a primary aliphatic alcohol in the presence of a catalytic amount of a basic compound in a temperature range from -20 DEG C. to 200 DEG C., at least 3 hydroxyl or amino group equivalents being used per 3 carboxylic acid amide group equivalents. The isomelamines prepared by the process according to the invention are valuable curing agents for epoxide resins.