title: Polymerization of penicillins. IV. Separation, isolation and characterization of ampicillin polymers formed in aqueous solution.
abstract: Polymeric substances formed from ampicillin sodium in aqueous solution have been separated according to charge by anion-exchange chromatography on a column of DEAE-Sephadex A-25 using a linear sodium chloride gradient at a constant pH of 7.4. The separated materials, ranging in size from the monomer to the octamer, have been characterized by various functional-group analyses. A homogeneous well-defined ampicillin dimer, tetramer and hexamer have been isolated from the effluent in high yields. The separation and isolation of the ampicillin polymers permit a conclusive establishment of their structures, which in turn has confirmed previous suggestions that the polymers are formed through a chain process involving aminolysis of ampicillin at the beta-lactam carbonyl moiety by the amino group of the side-chain of a second ampicillin molecule.
mesh_terms: D000667:Ampicillin / Q000302:isolation & purification*; D055598:Chemical Phenomena; D002621:Chemistry; D002852:Chromatography, Ion Exchange; D011108:Polymers / Q000302:isolation & purification
chemical_list: D011108:Polymers; D000667:Ampicillin