Premium
Theoretical study of the thermal isomerization of fulvene to benzene
Author(s) -
Madden L. K.,
Mebel A. M.,
Lin M. C.,
Melius C. F.
Publication year - 1996
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199612)9:12<801::aid-poc852>3.0.co;2-d
Subject(s) - chemistry , isomerization , fulvene , potential energy surface , computational chemistry , benzene , steric effects , photochemistry , cyclobutadiene , azulene , reaction mechanism , activation energy , stereochemistry , organic chemistry , molecule , catalysis
The potential energy surface for the thermal isomerization of fulvene to benzene was studied by modified Gaussian‐2 (G2M) and the bond additivity‐corrected fourth‐order perturbation Møller‐Plesset (BAC‐MP4) methods. Three isomerization pathways were investigated. One involves the intermediate prefulvene by a concerted mechanism, which has a significantly higher barrier. The second, also involving prefulvene and cyclopenta‐1,3‐dienylcarbene intermediates, has a barrier of 84·0 kcal mol −1 . The third, a multi‐step pathway, includes bicyclo[3.1.0]hexa‐1,3‐diene and cyclohexadiene carbene intermediates. The activation energy of the multi‐step pathway was calculated to be 74·3 kcal mol −1 , which is 7–11 kcal mol −1 higher than the experimental value obtained by a brief very low‐pressure pyrolysis (VLPP) study. RRKM calculations were performed on the multi‐step pathway in order to determine the rate of isomerization. These theoretical results cast doubt on the validity of the VLPP data. © 1996 John Wiley & Sons, Ltd.