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Title: Why alpha-azido five-membered heterocycles decompose so fast? An ab initio molecular orbital study
Authors: Sengupta, D ×
Nguyen, Minh Tho #
Issue Date: 1997
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Series Title: Tetrahedron vol:53 issue:28 pages:9647-9656
Conference: date:CATHOLIC UNIV LEUVEN,DEPT CHEM,B-3001 HEVERLEE,BELGIUM
Abstract: Thermal decomposition process in the ground singlet state of several five-membered alpha-azido heterocycles analogous of azido-pyrazoles producing molecular nitrogen and ring-opened species has been investigated via ab initio molecular orbital theory at the MP2/6-31G(d,p) level. In most cases the decomposition is calculated to be a concerted but asynchronous process on the closed-shell singlet ground state of the azides. The five-membered ring is in fact found to be intact at the transition state. The activation barriers for the decomposition are found to decrease in the order: thiophenes>furans>pyrroles. Decomposition of phenyl azide is found to be more difficult to achieve than those of five-membered heterocycles. The higher energy demand for phenyl azide decomposition is probably due to smaller charge transfer between the azido group and the ring when compared to those of five-membered heterocycles during the decomposition. The stability of the transition state due to an internal electrostatic force was also found to be larger in the case of the five-membered heterocycles. The fate of the different products has not been considered. (C) 1997 Elsevier Science Ltd.
ISSN: 0040-4020
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Quantum Chemistry and Physical Chemistry Section
× corresponding author
# (joint) last author

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