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Theoretical Calculations of β-Lactam Antibiotics. Part VII. Influence of the solvent on the basic hydrolysis of the β-lactam ring

✍ Scribed by Juan Frau; Josefa Donoso; Francisco Muñoz; Francisco Gracia-Blanco

Publisher
John Wiley and Sons
Year
1996
Tongue
German
Weight
571 KB
Volume
79
Category
Article
ISSN
0018-019X

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✦ Synopsis

We used semi-empirical and ab initio calculations to investigate the nucleophilic attack of the OHion on the 8-lactam carbonyl group. Both allowed us to detect reaction intermediates pertaining to proton-transfer reactions rather than the studied reaction. We also used the PM3 semi-empirical method to investigate the influence of the solvent on the process. The AMSOL method predicts the occurrence of a potential barrier of 20.7 kcal/mol due to the desolvation of the OHion in approaching theb-lactam carbonyl group. Using the supermolecular approach and a H,O solvation sphere of 20 molecules around the solute, the potential barrier is lowered to 17.5 kcal/mol, which is very close to the experimental value (16.7 kcal/mol).

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