GB466957A - Manufacture of 2:4:6-triamino-1:3:5-triazine - Google Patents

Abstract

2 : 4 : 6 - Triamino - 1 : 3 : 5 - triazine (melamine) is prepared by heating to above 100 DEG C., dicyandiamide or cyanamide in the presence of ammonia under anhydrous conditions or in the presence of less than 20 per cent of water calculated on the weight of dicyandiamide or cyanamide. Preferably a solid or liquid diluent, e.g. liquid ammonia, which acts as a heat buffer is employed. In examples: (1) ammonia gas is forced under pressure into an autoclave containing dicyandiamide and methyl alcohol, benzine, ethyl alcohol or nitrobenzene and heat applied; melamine is obtained by filtering and washing the product; (2) dicyandiamide is heated in an autoclave with liquid ammonia; (3) dried dicyandiamide is mixed with iron powder and heated in a sealed tube or is heated in the presence of ammonia gas in an autoclave; when the ammonia is not introduced part of the dicyandiamide furnishes the required ammonia by decomposition; (4) dicyandiamide is heated in a flask in the presence of copper bronze to 185--190 DEG C.; (5) a mixture of cyanamide and methylalcohol is saturated with ammonia and heated in a sealed tube; (6) liquid ammonia is introduced into an autoclave containing dicyandiamide and methyl alcohol and heat applied; (7) dicyandiamide is mixed with 22 per cent aqueous ammonia and heated in a bomb. Zinc powder, magnesium oxide, asbestine and dioxane are mentioned as diluents.