Related Experiment Video
Updated: Aug 18, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Configurational stability of 2-benzoylcyclohexanone: unexpected solvent effects on the rate of racemization
Gilbert E Tumambac1, Christopher J Francis, Christian Wolf
1Department of Chemistry, Georgetown University, Washington, DC 20057, USA.
Abstract:
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 degrees 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.
Related Concept Videos
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Stereochemical Effects of Enolization
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
Stereoisomerism of Cyclic Compounds
Racemic Mixtures and the Resolution of Enantiomers
SN1 Reaction: Stereochemistry
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...
