| 摘要 |
The present invention relates to a method of producing a highly pure crystal, which includes crystallization of a benzenesulfonamide derivative of the following formula (1) using a polar solvent as a good solvent (e.g., alcohol or a mixed solvent of alcohol and water) and water as a poor solvent, and a novel crystal of a nitrobenzenesulfonamide derivative of the following formula (2), which is an intermediate for the derivative, and a production method thereof:
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