We evaluated the rate and mechanism of decomposition of cefazolin methyl ester (Δ 3 ester) in phosphate buffer (pH 8.4). The decomposition of Δ 3 ester proceeded simultaneously via 3 pathways. The first pathway is production of Δ 2 ester (rate k 12) by isomerization and production of Δ 2 acid (k 23) by hydrolysis of the Δ 2 ester. The second pathway is the cleavage reaction of the β-lactam ring and simultaneous elimination of the substituent at ...
