Issue 7, 2000
From the journal:

Journal of the Chemical Society, Perkin Transactions 2

Thiol-catalysed hydrolysis of benzylpenicillin

Antonio Llinás,b   Josefa Donoso,*a   Bartolomé Vilanova,a   Juan Frau,a   Francisco Muñoza  and  Michael I. Page*b  

* Corresponding authors

a Departament de Química, Facultat de Ciències, Universitat de les Illes Balears, Palma de Mallorca, Spain

b Department of Chemical and Biological Sciences, The University of Huddersfield, Huddersfield, UK

Abstract

Thiolysis of benzylpenicillin has been investigated by HPLC and 1H-NMR techniques. Thiols catalyse the hydrolysis of benzylpenicillin through the formation of a thioester intermediate. The catalytically reactive form of the thiol has been demonstrated to be the thiolate anion. Variation of reactivity with changing basicity of the thiolate anion generates a Brønsted βnuc value of 0.96, indicating that the breakdown of the tetrahedral intermediate is the rate-limiting step, as occurs in aminolysis and alcoholysis. Solvent kinetic isotope effects of 2.2–2.4 indicate that the solvent, water, probably acts as a general acid catalyst in the breakdown of the tetrahedral intermediate. PM3 theoretical calculations support the proposal that breakdown of the tetrahedral intermediate is rate-limiting. The experimental activation energies for the thiolysis of benzylpenicillin vary from 6.9 to 10.4 kcal mol−1.

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Article information

DOI
https://doi.org/10.1039/B001091J
Article type
Paper
Submitted
08 Feb 2000
Accepted
10 Apr 2000
First published
24 May 2000

J. Chem. Soc., Perkin Trans. 2, 2000, 1521-1525

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Thiol-catalysed hydrolysis of benzylpenicillin

A. Llinás, J. Donoso, B. Vilanova, J. Frau, F. Muñoz and M. I. Page, J. Chem. Soc., Perkin Trans. 2, 2000, 1521 DOI: 10.1039/B001091J

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