79239-19-3Relevant articles and documents
Kinetics and mechanism of decomposition of cefazolin ester in phosphate buffer solution
Yamazaki, Yutaka,McEntagart, John,Shinozaki, Katsuhiko,Yazawa, Hisatoyo
, p. 599 - 601 (2007/10/03)
We evaluated the rate and mechanism of decomposition of cefazolin methyl ester (Λ3 ester) in phosphate buffer (pH 8.4). The decomposition of Λ3 ester proceeded simultaneously via 3 pathways. The first pathway is production of Λ2 ester (rate k12) by isomerization and production of Λ2 acid (k23) by hydrolysis of the Λ2 ester. The second pathway is the cleavage reaction of the β-lactam ring and simultaneous elimination of the substituent at position 3 (k14). The third pathway is production of Λ3 acid (k15) by hydrolysis of the carboxylic ester at position 4. Kinetic analysis of each pathway was performed. The reaction rate constant from Λ2 ester to Λ2 acid (k23) was the highest, and the reaction rate constant for the production of Λ2 ester by isomerization (k12) was similar to that for the elimination of the position 3 substituent by cleavage of the β- lactam ring (k14). The rate of production of Λ3 acid by hydrolysis of the position 4 carboxylic ester was the lowest. These results show that Λ3 ester decomposition under a basic condition predominantly occurs through cleavage reaction of the β-lactam ring and Λ2 ester production by isomerization. Since the production of Λ2 acid markedly depended on the production of Λ2 ester by isomerization, Λ2 ester production is the rate- limiting step of this pathway.
