Polymorphs of 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazolecarboxylic acid and method of producing the same

摘要

The present invention provides a technique of selectively producing a polymorph crystal C of 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazolecarboxylic acid. The present invention also provides a method of producing the said polymorphs of 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazolecarboxylic acid, which comprises crystallizing under the conditions defined by a specific temperature and a composition of a mixed solvent of methanol and water.