| 摘要 |
PURPOSE:To obtain a compound useful as an antimicrobial agent, by crystallizing pipemidic acid anhydride or a mixture thereof with trihydrate thereof in an aqueous medium, and washing the resultant crystals with an organic solvent to remove adherent water therefrom. CONSTITUTION:Pipemidic acid or a mixture thereof with trihydrate thereof is crystallized in water and an organic solvent miscible with the water, e.g. a lower alcohol or tetrahydrofuran. The adherent water is suspended in an organic solvent, e.g. n-propyl alcohol or tetrahydrofuran, without eliminating the water of crystallization and removed while stirring thorough to afford the aimed substance expressed by the formula. The above-mentioned pipemidic acid trihydrate has no adherent water, and is obtained by removing only the contained organic solvent.
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