| 摘要 |
A method for preparing a crystal of 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carbamoyl]benzoic acid having a single endothermic peak approximately at 233° C. in differential scanning calorimetry, which comprises the step of recrystallizing a crystal of 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carbamoyl]benzoic acid from a mixture of water and ethanol. The method enables selective preparation of type-II crystals which are stable against physical impact. The resulting crystals are free from highly toxic hexane as a residual solvent, and preferably used as an active ingredient of pharmaceuticals.
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