Theoretical study of substituent effects in the unimolecular decomposition of N-chloro-α-amino acid anions. Analysis of transition structure and molecular reaction mechanism
✍ Scribed by J. Andrés; J. J. Queralt; V. S. Safont; M. Canle; J. A. Santaballa
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 637 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0894-3230
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✦ Synopsis
The unimolecular decomposition of substituted N-chloro-a-glycine anions was examined by an ab initio method using the 6-31G* basis set to obtain an insight into the relationship between transition-state structure and reactivity. The complete potential energy surface was explored and the stationary points corresponding to reactant and transition structure were localized. A reaction analysis by correlation of bond orders revealed that the reaction mechanism corresponds to an asynchronous fragmentation. The transition structure for all the compounds has an antiperiplanar conformation between the C-C and N-CI bond breaking and it has a product-like character. The influence of the substitution on the a-carbon and on the nitrogen is discussed. When the size and number of substituents on the a-carbon and to a lesser extent on the nitrogen atom increase the relative energy decreases. The size of the substituent produces perpendicular effects and the type and number of substituents give parallel effects.