Method for producing high melting point crystals of phenoxypropionic acid derivative

摘要

A method for producing beta crystals of ethyl (R)-2-[4-(6-chloro-2-quinoxalin-2-yloxy)phenoxy]propionate, which is characterized by heating alpha crystals, or alpha a crystals and beta crystals, within a range of from 50° C. to lower than the melting point of the alpha crystals.