Process for the preparation of cefixime
The present invention provides an improved process for the preparation of Cefixime of formula (I), a cephalosporine antibiotic with an improved quality in regard to color and solubility. This process includes: (i) reaction of 7-β-(4-chloro-2-alkoxycarbonyl methoxyimino-3-oxobutyromido)-3-cephem-4-carboxylic acid (V) with thiourea at pH 5.0 to 6.0 at temperature 25-40° C. in water, (ii) carbon treatment to the reaction mixture in presence of sodium dithionite or ethylenediaminetetraacetic acid (EDTA) followed by filtration, (iii) acidification of the filtrate obtained in step (ii) to pH 2.0 to 3.0 with acid at 50-80° C. to give cefixime ester (IV) (iv) alkaline hydrolysis of cefixime ester of formula (IV) in water followed by acidification to pH 5.0 to 6.0, (v) precipitation of cefixime (I) by adding ketone solvent followed by acidification to pH 2.0 to 3 and (vi) isolation of solid.
1. A process for preparation of cefixime of formula (I)
which comprises:
(i) reaction of 7-β-(4-chloro-2-alkoxycarbonyl methoxyimino-3-oxobutyromido)-3-cephem-4-carboxylic acid of formula V wherein R represents (C 1 -C 4 ) alkyl group with thiourea at pH 5.0 to 6.0 at temperature 25-40° C. in water,
(ii) carbon treatment to the reaction mixture in presence of sodium dithionite or ethylenediaminetetraacetic acid (EDTA) followed by filtration,
(iii) acidification of the filtrate obtained above in step (ii) to pH 2.0 to 3.0 with acid at 50-80° C. to give cefixime ester of formula IV wherein R 1 represents (C 1 -C 4 ) alkyl group and R 2 represents hydrogen,
(iv) alkaline hydrolysis of cefixime ester of formula (IV) wherein R 1 represents (C 1 -C 4 ) alkyl group and R 2 represents hydrogen obtained above in water followed by acidification to pH 5.0 to 6.0,
(v) precipitation of cefixime (I) by adding solvent, the solvent comprising a ketone, followed by acidification to pH 2.0 to 3, and
(vi) isolation of solid.
2. A process according to claim 1 wherein, step (i) is carried out at pH 5.5 to 5.8.
3. A process according to claim 1 wherein, step (i) is carried out at 30-35° C.
4. A process according to claim 1 wherein, acidification in step (iii) is carried out to pH 2.2 to 2.4.
5. A process according to claim 1 wherein, acidification in step (iii) is carried out at 60-75° C.
6. A process according to claim 1 , further comprising isolating the cefixime ester of formula (IV) wherein R 1 represents (C 1 -C 4 ) alkyl group and R 2 represents hydrogen obtained in step (iii), wherein isolating is carried out at 50-80° C.
7. A process according to claim 1 wherein, alkaline hydrolysis in step (iv) is carried out in water by using alkali metal hydroxide.
8. A process according to claim 1 wherein, alkaline hydrolysis in step (iv) is carried out at 0-30° C.
9. A process according to claim 1 wherein, in step (iii) the acidification comprises adding dilute inorganic or organic acid.
10. A process according to claim 1 wherein, in step (v) the precipitation is carried out by adding solvent selected from the group consisting of comprising-acetone and methyl ethyl ketone.
11. A process according to claim 1 wherein, in step (iii) the acidification is carried out to pH 2.0 to 2.5.
12. The process of claim 9 , wherein acidification in step (iii) comprises adding HCl, H 2 SO 4 , or acetic acid.
13. The process of claim 12 , wherein acidification in step (iii) comprises adding HCl.
14. The process of claim 5 , wherein acidification in step (iii) is carried out at 60-70° C.
15. The process of claim 14 , wherein acidification in step (iii) is carried out at 64-68° C.
16. The process of claim 6 , wherein isolating is carried out at 60-70° C.
17. The process of claim 16 , wherein isolating is carried out at 64-68° C.
18. The process of claim 7 , wherein the alkali metal hydroxide is selected from the group consisting of sodium hydroxide and potassium hydroxide.
19. The process of claim 18 , wherein the alkali metal hydroxide is sodium hydroxide.
20. The process of claim 8 , wherein alkaline hydrolysis in step (iv) is carried out at 0-5° C.
21. The process of claim 10 , wherein the solvent is acetone.