Dai-ichi Kogyo Seiyaku Co., Ltd.

Tsuyoshi Furukawa

Setsuo Nishibori

Hideaki Ohnishi

This invention relates to a method of producing a high-melting powder of 2,2-bis�4'-(2',3'-dibromopropoxy)-3',5'-dibromophenyl!propane characterized by comprising a step of adding water to a solution of 2,2-bis�4'-(2',3'-dibromopropoxy)-3',5'-dibromophenyl!-propane in an organic solvent in the presence of a surfactant to give a water-in-oil emulsion and a step of removing the organic solvent from the emulsion in the presence of a crystal nucleus to induce crystallization to give an aqueous dispersion of 2,2-bis�4'-(2',3'-dibromopropoxy)-3',5'-dibromophenyl!propane. In accordance with this invention, crystallization is carried out in the state of an emulsion under assistance of a surfactant so that an ordinary stirrer can be used in production without resort to any special high-shear stirring equipment. Moreover, since a high-melting grade of 2,2-bis�4'-(2',3'-dibromopropoxy)-3',5'-dibromophenyl!propane is obtained as an aqueous dispersion, workability and safety in the subsequent processing are improved.

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Kyoto, Japan

Tsuyoshi Furukawa