Process for the preparation of 2,4,5-triamino-6-hydroxypyrimidine by catalytic hydrogenation of 2,4-diamino-6-hydroxy-5-nitrosopyrimidine

摘要

Prod. of 2,4,5-triamino-6-hydroxypyrimidine (I) involves catalytic hydrogenation of 2,4-diamino-6-hydroxy 5-nitropyrimidine (II) at elevated pressure and temp. in an aw. medium opt. contg. organic solvent and/or inert salt, using a noble metal hydrogenation catalyst (III). The novel features are that (a) hydrogenation is carried out in acid, neutral or slightly alkaline medium below pH9 and no alkali is added before or during hydrogenation; and (b) after hydrogenation, alkali is added in the amt. to dissolve (I) and the soln. is sepd. from (III). Pref. hydrogenation is carried out below pH 9.0, (at pH 3-8.5); a H2 pressure of 3-160 (10-60) bar; and temp. of 50-150 (70-120 Deg. C). (II) is used in a concn. of 0.4-3.0 mole/l and pref. is in the form of an aq. suspension prepd. from guanidine salts, alkali alcoholates and cyanoacetate esters and conversion to the nitroso cpd., without isolading intermediates or sepg. by-prods. (III) is Ru. Pd, Pt or their cpds., pref. Pd, Pd0, pt or Pt02 on charcoal. 0-50% fresh catalyst is added to the spent catalyst for the next batch. After reaction, (I) is dissolved by adding 0.9-1.2 mole NaOH or KOH/mole (II) used.