Hydrochloric Acid → Disodium

Participants

Reaction Steps

To a stirred solution of 266 mg. (0.001 mole ) of 6-amino-2,2-dimethyl-3-(O-methylphosphono)penam in 8 ml. of water is added dropwise dilute aqueous sodium hydroxide to obtain a pH of 6.1. To this solution is then added 235 mg. (0.0013 mole) of phenylmalonic acid, followed by 190 mg. (0.001 mole) of 1-ethyl-3-(3-dimethylaminoprop-1-yl)carbodiimide hydrochloride. The solution is stirred for 3.5 hours, during which time the pH is maintained in the range from 6.1 to 6.3 by the dropwise addition of dilute hydrochloric acid. At this point, the pH is raised to 7.3 by the addition of saturated sodium hydrogen carbonate solution, and the reaction mixture is washed with ethyl acetate. The wash is discarded. The aqueous phase is then adjusted to pH 2 using dilute hydrochloric acid, and then it is extracted twice with 30 ml. portions of ethyl acetate. The combined extracts are dried, and concentrated to a volume of about 25 ml. To this solution is added a solution of 330 mg. (0.002 mole) of sodium 2-ethylhexanoate in 2.0 ml. of ethyl acetate. The precipitate which forms is filtered to give the disodium salt of 6-(2-carboxy-2-phenylacetamido)-2,2-dimethyl-3-(O-methylphosphono)penam.

Provenance & Evidence