Anhydrous ampicillin prepn - without isolation of hydrated ampicillin

摘要

The anhydrous form of ampicillin is produced by condensing 6-APA with a cpd. C6H5-CH(NH-R)-COR1 (where R is H or a gp. -C(CH3)=CH-COCH3 or -C(CH3)=CH-COOC2H5 and R1 is Cl or -O-CO-R11 in which R11 contains 1-7 C atoms, or R and R1 together form a -CO-O-) in an aqs. soln. of a 3-10C aliphatic, alicyclic or alkyl aryl ketone or in a 1-3C chlorinated solvent and, after completion of the reaction, evaporating the solvent at 20-100 degrees C. The new procedure gives anhydrous ampicillin (which is more stable and gives higher blood antibiotic levels than the hydrated form) directly, and the yield is better than that of procedures involving the isolation and separate dehydration of hydrated ampicillin.