Edaravone polymorphic substance and preparation method thereof

The invention provides two stable new crystal forms of edaravone (3-methyl-1-phenyl-2-pyrazoline-5-ketone). New edaravone crystal forms are crystal forms II and III. The thermo-gravimetric spectrum diagram of the crystal form II shows that each part of edaravone molecules contains 2 parts of crystal water. The differential scanning calorimetry (DSC) spectrum diagram of the crystal form II shows that the crystal form II has two high heat absorption peaks at the temperatures of 48.5 DEG C and 68.3 DEG C, and the melting decomposition temperature is 129.1 DEG C (peak value). The thermo-gravimetric spectrum diagram of the crystal form III shows that the edaravone molecules do not contain crystal water (solvent). The DSC spectrum diagram of the crystal form III shows that the crystal form III has a small heat absorption peak at the temperature of 107.0 DEG C, and the melting decomposition temperature is 126.9 DEG C (peak value). The new edaravone crystal forms are high in stability, high in dissolution and convenient to store. A preparation method for the new edaravone crystal forms is simple, convenient and feasible; because solvents with high boiling points and high toxicity are not used, the preparation method is favorable for environment friendliness; and the preparation method is suitable for industrialized production, and has high application value.