GB639432A - Improvements in and relating to the preparation of penicillin salts - Google Patents

Abstract

Ammonium penicillin is precipitated from a solution of penicillin in a non-polar organic solvent by addition thereto of concentrated aqueous ammonia, or, if the penicillin solution contains a proportion of water (not in excess of that required to saturate the solution), by passing in ammonia gas; the precipitate is separated and treated with acetone when substantially pure ammonium penicillin is left in the solid form. The starting material may be (1) the solution obtained by extracting the acidified culture medium with butyl acetate, treating with water and sodium hydroxide at pH 7, acidifying the aqueous solution and reextracting with ether; (2) the result of extracting with ether an acidified aqueous solution of a partially-purified penicillin salt; or (3) solutions of the various penicillins such as G, X and F alone or mixed in any proportion. Chloroform is also mentioned as a suitable non-polar solvent. The addition of ammonia is preferably continued until the supernatant liquor is slightly on the acid side of neutrality, e.g. pH 6.5-6.7. The final treatment with acetone is preferably carried out at or near room temperature. Examples are given of the process of the invention using ammonia gas and the aqueous solution, and the conversion of the product into the sodium salt. Specification 578,590 is referred to. According to the Provisional Specification, the acetone may contain water or may be replaced by any neutral water-miscible or partially water-miscible organic solvent or a mixture thereof with water, aqueous butanol being specified.