Phosphoric Acid → HCID 5362051、化合物

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The pH of the ceftazidime solution was lowered to 4.5 with 4M phosphoric acid, and the solution was seeded. The solution was stirred for 21/2 hr at 0-5° C., during which the pH had risen to 4.7 and a large amount of crystals had formed. Phosphoric acid (4M) was then added dropwise over a 1 hr period to achieve a pH of 3.7. More acid was added dropwise over the next 1/2 hr to maintain this pH. After the pH was stabilized, the slurry was stirred slowly in an ice bath for 1 hr. The crystals were filtered and washed twice with cold deionized water (2×30 mL) and then with cold acetone (30 mL). The product was dried overnight at ambient temperature at a pressure of about 80 mm Hg. This procedure gave 13.57 g of ceftazidime pentahydrate. The assay was 85.4%, and the corrected yield was 77.3%. Another 11.1% yield was obtained from the combined mother liquors and washes.

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