Doddrell, David and Charrier, Claude and Hawkins, Bruce L. and Crain, W. O., Jr. and Harris, Leland and Roberts, John D. (1970) Nuclear magnetic resonance spectroscopy. Variable-temperature ^(13)C and ^(19)F study of the chair-chair interconversion of 1,1,3,3-tetramethylcyclohexane and gem-difluoro-1,1,3,3-tetramethylcyclohexanes. Proceedings of the National Academy of Sciences of the United States of America, 67 (3). pp. 1588-1592. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:DODpnas70a
- Published Version
See Usage Policy.
Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:DODpnas70a
A variable-temperature, proton noise-decoupled, ^(13)C nmr spectral study of the chair-chair interconversion in 1,1,3,3-tetramethylcyclohexane has demonstrated the utility of ^(13)C spectra for probing conformational equilibria. There is a much larger chemical-shift difference between the carbons of axial and equatorial methyl groups than between the protons of these methyl groups, 133 Hz compared to 7.5 Hz. Comparison of the activation parameters determined from the ^(13)C spectra of 1,1,3,3-tetramethylcyclohexane with those determined from a variable-temperature ^(19)F study on 2,2,6,6-tetramethyl-1,1-difluorocyclohexane shows that the introduction of a gem-difluoro group into the ring causes significant steric interactions. The ^(13)C chemical shifts for 1,1,3,3-tetramethylcyclohexane reflect the importance of the methyl-methyl 1,3-diaxial interactions.
|Additional Information:||© 1970 National Academy of Sciences. Communicated September 3, 1970. Supported by the National Science Foundation. Contribution no. 4083 from the Gates and Crellin Laboratories.|
|Other Numbering System:|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||18 Aug 2006|
|Last Modified:||15 Oct 2015 03:59|
Repository Staff Only: item control page