Racemization process of R-zopiclone

摘要

In one of the embodiments, the present invention provides a racemization process comprising: removing the organic solvent from a mother liquor comprising R-zopiclone malate, eszopiclone malate and an organic solvent to obtain a mixture of R-zopiclone malate and eszopiclone malate; mixing the mixture with water to obtain a solution; neutralizing R-zopiclone malate and eszopiclone malate in the solution to obtain a precipitate of R-zopiclone and eszopiclone; filtering the precipitate; mixing the precipitate of R-zopiclone and eszopiclone with DBU and an organic inert solvent having a boiling point of at least 80° C.; heating; and cooling to obtain a zopiclone racemate.