Process for preparing 1,3-dimethy-4,5-diaminouracil

A process for preparing 1,3-dimethyl-4,5-diaminouracil by catalytic reduction of 1,3-dimethyl-4-amino-5-nitrosouracil in the presence of a palladium/charcoal catalyst, characterised in that, in an aqueous suspension, the 1,3-dimethyl-4-amino-5-nitrosouracil is adjusted to a pH in the range from 7 to 10 with an aqueous solution of an alkali compound and subsequently hydrogenation is carried out under a hydrogen pressure in the range from 1 to 20 bar within a temperature range from 20.degree. to 60.degree. C. and after the uptake of hydrogen has ceased, formic acid is added to the reaction mixture at a temperature in the range from 15.degree. to 40.degree. C. until all the 1,3-dimethyl-4,5-diaminouracil has gone into solution, the reaction mixture is filtered off from the catalyst and the 1,3-dimethyl-4,5-diamino-uracil is isolated in the form of the formate thereof.