CHEMISTRY OF PENICILLANIC ACIDS .I. 6,6-DIBROMO- AND 6,6-DI-IODO-DERIVATIVES

6,6-Dibromopenicillanic acid (IIIa) and 6,6-di-iodopenicillanic acid (IIIc) have been observed in the products of the deamination of 6β- aminopenicillanic acid (Ia) in the presence of sodium bromide and sodium iodide respectively. Deamination of (Ia) in the presence of bromine has resulted in the isolation of 6,6-dibromopenicillanic acid (IIIa) in 35% yield. The 1β-(Va) and 1α-(VIa) sulphoxides of this acid are described, together with some of its properties.