METHOD FOR PRODUCING HIGH-PURITY MONTELUKAST

摘要

Provided is a method for producing high-purity montelukast by effectively removing impurities which are inevitably produced as by-products or mixed in during synthesis of montelukast. This method for producing montelukast or salts thereof comprises (1) a step of preparing a solution which is divided into an organic phase in which crude montelukast including impurities is dissolved and an acidic aqueous phase, (2) a step of adjusting pH of the aqueous phase of the solution to 7.0 or more and less than 8.8, (3) a step of separating the organic phase from the aqueous phase, and (4) a step of collecting montelukast or salts thereof from the organic phase.