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Details for Patent: 5,354,860

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Details for Patent: 5,354,860

Title: Process for making pure S-timolol hemihydrate
Abstract:A process for preparing S-(-)-3-morpholino-4-(3-tert-butylamino-2-hydroxypropoxy)-1,2,5-thiadiazol e hemihydrate, i.e. S-timolol hemihydrate, wherein the compound is crystallized in optically pure form as the hemihydrate from a mixture containing an organic solvent, water and S-timolol base. This process can be used in the purification of S-timolol, especially for the removal of the corresponding R-enantiomer.
Inventor(s): Peralampi; Markku (SF-36200 Kangasala, FI)
Assignee:
Filing Date:Jul 08, 1992
Application Number:07/910,789
Claims:1. A process comprising the step of preparing the compound S-(-)-3-morpholino-4-(3-tert-butylamino-2-hydroxypropoxy)-1,2,5-thiadiazol e hemihydrate which is commonly named S-timolol hemihysdrate, wherein the compound is crystallized in optically pure form as the hemihydrate from a mixture containing at least one organic solvent and water and s-timolol base wherein the organic solvent mixture is one in which S-timolol base is soluble but in which, in the presence of water, S-timolol hemihydrate is sparingly soluble.

2. Process according to claim 1, wherein S-timolol base is dissolved in an organic solvent, at least a stochiometric amount of water is added for the formation of S-timolol hemihydrate, and S-timolol hemihysdrate is crystallized.

3. Process according to claim 1, wherein the solvent mixture is an aqueous toluene-hexane mixture.

4. Process according to claim 1, wherein the solvent mixture is aqueous di-isopropyl ether.

5. Process according to claim 1, wherein the solvent mixture is aqueous methylene chloride.

6. Process according to claim 1 wherein the S-timolol hemihydrate is prepared from a salt form of S-timolol base as a starting material which is treated with an alkaline agent to form the S-timolol base contained in the mixture from which the hemihydrate is crystallized.

7. Process according to claim 6, wherein the alkaline agent is sodium hydroxide.

8. Process according to claim 1 wherein the S-timolol contained in the mixture is prepared by treating a salt form of S-timolol base with an alkaline agent.

9. Process according to claim 8 wherein the salt form of S-timolol base is S-timolol maleate.

10. A process for the purification of S-(-)-3-morpholino-4-(3-tert-butylamino-2-hydroxypropoxy)-1,2,5-thiadiazol e commonly known as S-timolol, or its salt, especially for the removal of the corresponding R-enantiomer, comprising the steps of (a) crystallizing in optically pure form a compound selected from the group consisting of S-(-)-3-morpholino-4-(3-tert-butylamino-2-hydroxypropoxy)-1,2,5-thiadiazol e and its salt as S-timolol hemihysdrate from a mixture containing at least one organic solvent and water and S-timolol base wherein the organic solvent mixture is one in which S-timolol base is soluble but in which, in the presence of water, S-timolol hemihydrate is sparingly soluble, and (b) converting the crystallized hemihydrate back to S-timolol base or its salt.
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