| 摘要 |
The present invention relates to a process for the preparation of crystalline fipronil comprising at least 85% by weight of a crystalline modification I fipronil being present in the monoclinic system having the centrosymmetric space group C2/c, showing, in an X-ray powder diffractogram recorded using Cu-Kα radiation at 25°C shows at least, 5 of the following reflections: (1) 2θ=11.8±0.2°, (2) 2θ=14.5±0.2°, (3) 2θ=15.8±0.2°, (4) 2θ=18.2±0.2°, (5) 2θ=23.6±0.2°, (6) 2θ=24.1±0.2°, (7) 2θ=27.4±0.2°, (8) 2θ=29.5±0.2°, (9) 2θ=32.2±0.2°. A process comprises the steps of preparing a solution of a solid form of fipronil being different from the crystalline modification I in a solvent S, the crystallization of fipronil; and concentration of the obtained solution. |
