Method for extracting asymmetric β-diketone compound from β-diketone compound

A method of extracting an asymmetric β-diketone compound of Chemical Formula 1 from a β-diketone compound comprising at least either a symmetric β-diketone compound of Chemical Formula 2 or a symmetric β-diketone compound of Chemical Formula 3, said symmetric β-diketone compound being mixed in the asymmetric β-diketone compound, the method comprising the steps of:

• (A):
• adjusting a pH of a mixed solution of the β-diketone compound and water 11.5 or more and dissolving the β-diketone compound into water to form a β-diketone compound solution;
• (B):
• subsequently adjusting the pH of the β-diketone compound solution 9.5 or less and recovering the asymmetric β-diketone compound of Chemical Formula 1 separated from the β-diketone compound solution;
• and
• at least either of:
• (a):
• setting the upper limit of the pH of the mixed solution to 12.5 to form a β-diketone compound solution in the step (A) and bringing the β-diketone compound solution into contact with a hydrophobic solvent to thus transfer the symmetric β-diketone compound of Chemical Formula 3 into the hydrophobic solvent;
• or
• (b):
• setting the lower limit of the pH of the β-diketone compound solution to 8.0 in the step (B) and separating and recovering the asymmetric β-diketone compound of Chemical Formula 1 separated from the β-diketone compound solution:
• (in each chemical formula, R1 and R2, which are substituents, are alkyl groups, and have a relationship of the number of carbon atoms in R1<the number of carbon atoms in R2, and R3 is hydrogen or an alkyl group.).