Patent ID: 8481715

Claim:
A method for isolating crystalline Form I of 5-azacytidine substantially free of other forms, the method comprising: recrystallizing 5-azacytidine from a solvent mixture comprising at least one polar aprotic solvent and at least one co-solvent selected from the group consisting of: 1,1,2-trichloroethene, 1,2-dichloroethene, 1,2-dimethoxyethane, 1,4-dioxane, 1-butanol, 1-pentanol, 1-propanol, 2-butanol, 2-ethoxyethanol, 2-methoxyethanol, 2-methyl-1-propanol, 2-propanol, 3-methyl-1-butanol, acetone, acetonitrile, anisole, butyl acetate, chlorobenzene, cumene, cyclohexane, dichloromethane, ethyl acetate, ethyl ether, ethyl formate, ethyleneglycol, formamide, isobutyl acetate, isopropyl acetate, methyl acetate, methylbutyl ketone, methylcyclohexane, methylisobutyl ketone, N,N-dimethylacetamide, N,N-dimethylformamide, nitromethane, propyl acetate, pyridine, sulfolane, tert-butylmethyl ether, tetrahydrofuran, and tetralin, by cooling the solvent mixture from a temperature at which the 5-azacytidine dissolves completely to about −20° C.; and isolating the recrystallized 5-azacytidine.