Edaravone polymorphs and preparation method

The present invention provides two stable edaravone (3-methyl-1-phenyl-2-pyrazoline-5-one) is a new crystalline form, edaravone new crystalline form of Form Ⅱ and Ⅲ . Ⅱ crystalline form exhibiting each thermogravimetric edaravone molecules containing 2 parts of water of crystallization. The difference thermogram (DSC) display, and at ~ 68.3 ℃ ~ 48.5 ℃ has two endothermic peaks greater; melting temperature was 129.1 deg.] C decomposition (peak value). Ⅲ crystalline form exhibiting thermogravimetric edaravone the molecule and containing no crystal water (solvent). The difference thermogram (DSC) showed ~ 107.0 ℃ at a small endothermic peak; melting temperature was 126.9 deg.] C decomposition (peak value). Edaravone new crystalline form of the present invention good stability, good solubility, easy storage. The preparation method is simple, without toxicity and high boiling point solvents, environmentally friendly, suitable for industrial production, a greater value.