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US 6,297,384 B1Granted
Process for the preparation of 1,2,4-thiadiazoles
AssigneeThe Procter & Gamble Company
InventorJoseph K. Agyin
Life of this patent
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Abstract
3-[N′-(benzoyl)thioureido]-5-substituted-1,2,4-thiadiazoles are debenzoylated in an aqueous KOH solution. This process provides the 5-substituted-3-thioureido-1,2,4-thiadiazoles in unexpectedly high yield and purity as compared to similar processes employing NaOH.
Claims22
A process for the preparation of a compound of the Formula I
- comprising the steps of:
- (a) treating a compound of the Formula II
- with KOH in the presence of a reaction solvent comprising an aqueous solvent at a temperature of about 50-70° C. and for a period of about 0.5-1.5 hours to form the compound of the formula I, wherein the concentration of KOH in the reaction solvent is about 2-3 M;
- (b) separating the compound of the Formula I from the alkaline reaction solvent;
- (c) washing the compound of the Formula I with an aqueous solution;
- and
- (d) drying the compound of the Formula I;
- wherein the compound of Formula I contains less than 10% by wt. of undesired by-products.
5 more elements
A process for the preparation of a compound of the Formula I
- comprising the steps of:
- (a) treating a compound of the Formula II
- with KOH in the presence of a reaction solvent comprising an aqueous solvent at a temperature of about 50-70° C. and for a period of about 0.5-1.5 hours to form the compound of the formula I, wherein the concentration of KOH in the reaction solvent is about 2-3 M;
- (b) acidifying the reaction solvent with an acid having a pKa less than that of benzoic acid after completion of the reaction;
- (c) basifying the acidic reaction solvent to a pH greater than about 7;
- (d) separating the compound of the Formula I from the alkaline reaction solvent;
- (e) crystallizing the compound of the Formula I in a crystallization solvent;
- and
- (f) drying the compound of the Formula I;
- wherein the compound of Formula I contains less than 10% by wt. of undesired by-products.
7 more elements
A process for the preparation of a compound of the Formula I
- comprising the steps of:
- (a) treating a compound of the Formula II
- with KOH in the presence of a reaction solvent comprising a polar or protic solvent at a temperature of about 50-70° C. and for a period of about 0.5-1.5 hours to form the compound of the formula I;
- and
- (b) isolating the compound of Formula I by separating the solid form of the compound from the reaction solvent;
- wherein the compound of Formula I contains less than 5% by wt. of undesired by-products.
3 more elements
Dependencies are inferred from the claim text.