Hydrolysis of cephalosporins in strongly acid medium.

The hydrolysis of cephalexin, cephalothin and cephaloridine in strongly acid medium (10--25% sulfuric acid) at high temperature (approximately 100 degrees C) was studied. The hydrolysis proceeds with a high rate (10--15 min are necessary for complete hydrolysis) and results in definite products with low mol.-wt. The hydrolysis under such hard conditions affects the side chain in 3-position, in some cases the C--N bond in the amido group in 7-position, and leads to a total cleavage of the beta-lactam ring, giving thiazine compounds. The reaction products were identified using IR and UV spectral data, thin-layer and gas chromatography, and some characteristic reactions of functional groups. The results of the investigation were used for development of photometric procedures for determination of cephalosporins.