Method for Purifying a Pyrazolinone Derivative

A method for purifying a pyrazolinone derivative comprising a step of mixing a solution containing a mixture containing the pyrazolinone derivative represented by the formula (1) and a good solvent which can dissolve the pyrazolinone derivative with a poor solvent to crystallize the pyrazolinone derivative,

• wherein R1, R2, R3, R4 and R5 independently represent a hydrogen atom, a halogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxyalkyl group, an alkoxyalkoxy group, a haloalkoxy group, an alkylthio group, a haloalkylthio group, a cyano group, a nitro group, an optionally substituted phenyl group, or an optionally substituted phenoxy group;
• or adjacent two of R1, R2, R3, R4 and R5 together represent —CH═CH—CH═CH— or an alkylene group, and a carbon atom(s) contained in the —CH═CH—CH═CH— or alkylene group is(are) optionally replaced by an oxygen atom(s), and a hydrogen atom(s) contained in the —CH═CH—CH═CH— or alkylene group is(are) optionally substituted with a halogen atom(s) or an alkyl group(s);
• R6 represents an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted phenyl group or an optionally substituted alicyclic hydrocarbon group;
• X represents an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted phenyl group, an optionally substituted alkoxy group, an optionally substituted alkenyloxy group, an optionally substituted alkynyloxy group, an optionally substituted phenoxy group, an optionally substituted alkylthio group, an optionally substituted alkenylthio group, an optionally substituted alkynylthio group, an optionally substituted phenylthio group, or an optionally substituted alicyclic hydrocarbon group;
• and Y represents an oxygen atom or a sulfur atom;
• said method comprising the following first step to third step,
• First step:
• a step of adding part of a solution containing a mixture containing a pyrazolinone derivative represented by the formula (1) and a good solvent which can dissolve the pyrazolinone derivative to a poor solvent to obtain a mixed liquid (1),
• Second step:
• a step of crystallizing the pyrazolinone derivative represented by the formula (1) contained in the mixed liquid (1) obtained in the first step to obtain a mixed liquid (2) containing crystals of the derivative, and
• Third step:
• a step of further adding the remaining part of said solution to the mixed liquid (2) obtained in the second step to crystallize the pyrazolinone derivative represented by the formula (1).