PURPOSE: To obtain approximately spherical crystal of aggregated plural single crystals by dissolving a carboxylic acid such as 1,8-naphthyridine derivative, etc. in ammonia water and blending the solution with a water-immiscible organic solvent and an organic solvent having compatibility with both water and the organic solvent.
CONSTITUTION: A carboxylic acid (e.g., pyrido[2,3-d]pyrimidine derivative or 1,8-naphthyridine derivative) having a partial structure shown by the formula (A is C-H or N; R is lower alkyl, cyclopropyl, phenyl which may be replaced with halogen or R and substituent group at other position form hereto ring) is dissolved in 1-28W/V% ammonia water and blended with a water-immiscible organic solvent (e.g., dichloromethane) and an organic solvent (e.g., acetone) having compatibility with both water and the organic solvent and stirred for 5-120 minutes to give approximately spherical crystal. The crystal has smooth surface, excellent fluidity and can arbitrarily change the average particle diameter in a range of 100-2,000μm.
NAKAMURA YASUHIKO
MAKITA HIROKAZU
KAWASHIMA YOSHIAKI
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