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Configurational stability of 2‐benzoylcyclohexanone: Unexpected solvent effects on the rate of racemization
Author(s) -
Tumambac Gilbert E.,
Francis Christopher J.,
Wolf Christian
Publication year - 2005
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20148
Subject(s) - racemization , chemistry , enantiomer , solvent , enol , tautomer , chirality (physics) , isomerization , ethanol , solvent effects , enantioselective synthesis , medicinal chemistry , organic chemistry , stereochemistry , catalysis , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
The kinetics of the racemization of 2‐benzoylcyclohexanone 1 in hexanes, ethanol, and mixtures thereof have been investigated by time dependence of enantiomeric purity using enantioselective HPLC. In pure hexanes and ethanol, the racemization half‐lives were determined as 552 and 23.8 min, respectively, at 66°C. Surprisingly, racemization of 1 in mixtures of hexanes and ethanol was found to involve an induction period followed by a sigmoidal decrease of the enantiomeric excess with half‐lives varying between 11.5 and 24.0 min. This unexpected solvent influence on the rate of racemization of 1 was attributed to complex isomerization mechanisms involving three possibly interconverting enol tautomers of 1. Chirality 17:171–176, 2005. © 2005 Wiley‐Liss, Inc.