Abstract
The rate of aminolysis of benzylpenicillin and cephaloridine by hydroxylamine, unlike other amines, shows only a first order dependence on amine concentration. The rate enhancement compared with that predicted from a Bronsted plot for other primary amines with benzylpenicillin is greater than 106. This is much more than an α-effect and is compatible with rate-limiting formation of the tetrahedral intermediate due to a rapid intramolecular general acid catalysed breakdown of the intermediate. For cephaloridine, the rate enhancement is greater than 104 which demonstrates that β-lactam C-N bond fission and expulsion of the leaving group at C3′ are not concerted.
Original language | English |
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Pages (from-to) | 651-654 |
Number of pages | 4 |
Journal | Organic and Biomolecular Chemistry |
Volume | 2 |
Issue number | 5 |
Early online date | 9 Feb 2004 |
DOIs | |
Publication status | Published - 7 Mar 2004 |