Patent ID: 8536171
Filing Date: 2013-09-17
Classification: A61K,A61P,C07D

Abstract:
1. A method for preparing 5-amino-2,3-dihydrophthalazine-1,4-dione salts with alkali metals of the formula II where M represents a cation of Li, Na, K, said method comprising dissolving 5-nitro-2,3-dihydrophthalazine-1,4-dione in water solution of MOH, where M stands as above, with formation of solution of 5-nitro-2,3-dihydrophthalazine-1,4-dione alkali salt which is catalytically transformed into 5-amino-2,3-dihydrophthalazine-1,4-dione salt at the temperature of 40-90° C. by means of hydrogen under the pressure 1-4 MPa, at the presence of a catalyst of a transition metal (Pt, Pd) on active carbon, and separating crystalline 5-amino-2,3-dihydrophthalazine-1,4-dione salt by diluting the water solution with lower alcohol or cyclic lower ether after cooling to the temperature of −5° C. to −15° C., providing that there is used 5-nitro-2,3-dihydrophthalazine-1,4-dione formed in the reaction of 3-nitrophthalic acid anhydride with hydrazine hydrate in anhydrous acetic acid at the temperature 100-110° C. with distilling the mixture of acetic acid and water off.