Abstract: The invention is related to a method for preparing 5-amino-2,3-dihydrophthalazine-1,4-dione salt with alkali metals of the formula II wherein 5-nitro-2,3-dihydrophthalazine-1,4-dione is solved in water solution of MOH1 where M has the below mentioned meaning, with formation of solution of 5-nitro-2,3-dihydrophthalazine-1,4-dione alkali metal salt, which is catalytically transformed into 5-amino-2,3-dihydrophthalazine-1,4-dione salt at the temperature 40-900C by means of hydrogen under the pressure 1-4 MPa in at the presence of a transition metal catalyst (Pt, Pd) on activated carbon, and separation of crystalline 5-amino-2,3-dihydrophthalazine-1,4-dione salt is performed by water solution diluting with lower alcohol or cyclic lower ether with cooling to the temperature ?5° C. to ?15° C., providing that there is used 5-nitro-2,3-dihydrophthalazine-1,4-dione formed in the reaction of anhydride of 3-nitrophthalic acid with hydrazine hydrate in anhydrous acetic acid at the temperature 100-110° C.

Abstract: The invention is related to a method for preparing 5-amino-2,3-dihydrophthalazine-1,4-dione salt with alkali metals of the formula II wherein 5-nitro-2,3-dihydrophthalazine-1,4-dione is solved in water solution of MOH1 where M has the below mentioned meaning, with formation of solution of 5-nitro-2,3-dihydrophthalazine-1,4-dione alkali metal salt, which is catalytically transformed into 5-amino-2,3-dihydrophthalazine-1,4-dione salt at the temperature 40-900C by means of hydrogen under the pressure 1-4 MPa in at the presence of a transition metal catalyst (Pt, Pd) on activated carbon, and separation of crystalline 5-amino-2,3-dihydrophthalazine-1,4-dione salt is performed by water solution diluting with lower alcohol or cyclic lower ether with cooling to the temperature ?5° C. to ?15° C., providing that there is used 5-nitro-2,3-dihydrophthalazine-1,4-dione formed in the reaction of anhydride of 3-nitrophthalic acid with hydrazine hydrate in anhydrous acetic acid at the temperature 100-110° C.