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Kinetic studies on the pyramidal inversion of optically active selenonium imides
Author(s) -
Kamigata Nobumasa,
Taka Hideo,
Matsuhisa Ayumi,
Shimizu Toshio
Publication year - 1995
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/poc.610080303
Subject(s) - chemistry , optically active , kinetic energy , epimer , toluene , inversion (geology) , entropy of activation , reaction rate constant , stereochemistry , medicinal chemistry , kinetics , organic chemistry , quantum mechanics , physics , paleontology , structural basin , biology
Kinetic studies were carried out on the thermal epimerization by pyramidal inversion of optically active ( S )‐(−) Se ‐ and ( R )‐(+) Se ‐4‐[(‐)‐menthyloxycarbonyl]phenyl(2′,4′,6′‐triisopropylphenyl)selenonium‐ N ‐toluene‐4″‐sulphonimides (1). The first‐order rate constants for the pyramidal inversion of ( S )‐(−) Se ‐1 and ( R )‐(+) Se ‐1 were determined and the activation enthalpies and entropies were calculated. A fairly large difference was found in the activation parameters between optically active ( S )‐(−) Se ‐1 and ( R )‐(+) Se ‐1, i.e. a large negative activation entropy was obtained in the case of ( R )‐(+) Se ‐1.