ISSN:
0192-8651
Schlagwort(e):
Computational Chemistry and Molecular Modeling
;
Biochemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Informatik
Notizen:
As a model reaction for peptide and bond formation, the SN2 reactions between glycine and ammonia have been studied with and without amine catalysis: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm NH}_3 + {\rm NH}_2 {\rm CH}_2 {\rm COOH} + ({\rm NH}_3 ) \to {\rm NH}_2 {\rm CH}_2 {\rm CONH}_2 + {\rm H}_2 {\rm O} + ({\rm NH}_3 )$$\end{document} using ab initio molecular-orbital methods. For each of the catalyzed and uncatalyzed reactions, two reaction mechanisms have been examined: a two-step and a concerted mechanism. The stationary points of each reaction, including intermediate and transition states, have been identified and free energies calculated for all geometry-optimized reaction species to determine the thermodynamics and kinetics of the reaction. The calculations demonstrate that a second ammonia molecule catalyzes amide bond formation, and that the two-step mechanism is more favorable than the concerted one for the catalyzed reaction, while for the uncatalyzed reaction both mechanisms are competitive.
Zusätzliches Material:
5 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jcc.540040402
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