Purification method of lactone compounds containing unsaturated alkyl group by extraction with silver ion solution

1. A method of separating a lactone compound FK506 from a mixture, the method comprising:

providing a mixture which comprises the lactone compound FK506 and one or more other lactone compounds comprising a saturated alkyl group;

dissolving the mixture in a first organic solvent to prepare a solution of the lactone compounds, wherein the first organic solvent is a water-miscible organic solvent;

adding a second organic solvent, which is substantially incapable of dissolving the lactone compound FK506 and is substantially immiscible with water, to the solution of the lactone compounds to prepare a first mixed solution;

adding an aqueous silver ion (Ag + ) solution to the first mixed solution so that the lactone compound FK506 dissolves into to the aqueous silver ion solution;

separating at least part of the aqueous silver ion solution containing the lactone compound FK506 from the first and second organic solvents and collecting the aqueous silver ion solution;

adding a third organic solvent, which is water-immiscible and capable of dissolving the lactone compound FK506, to the separated aqueous silver ion solution to form a second mixed solution containing the lactone compound FK506; and

removing the silver ions from the second mixture to collect the lactone compound FK506.

2. The method of claim 1 , wherein the first organic solvent is selected from the group consisting of alcohols, ketones, dielectric aprotic organic solvents, and mixtures thereof.

3. The method of claim 1 , wherein the first organic solvent is selected from the group consisting of methanol, ethanol, isopropyl alcohol, acetone, acetonitrile, and mixtures thereof.

4. The method of claim 1 , wherein the silver ions are provided from at least one silver salt selected from the group consisting of silver nitrate (AgNO 3 ), silver acetate (AgCH 3 COO) and silver sulfate (AgSO 4 ).

5. The method of claim 1 , wherein the second organic solvent is selected from the group consisting of benzene, toluene, hexane, heptane, butanol, chloroform, and mixtures thereof.

6. The method of claim 1 , wherein the third organic solvent is selected from the group consisting of dichloromethane, ethyl acetate, isobutyl acetate, n-butyl acetate, t-buty acetate, and mixtures thereof.

7. The method of claim 1 , wherein said removing the silver ions comprises: adding an aqueous solution of NaCl to the second mixture, thereby precipitating the silver ions.

8. The method of claim 1 , wherein the precipitated silver ions are collected and used to prepare the aqueous silver ion solution for the same method.