NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY. CONFORMATIONAL PROPERTIES OF CYCLOBUTANES: VARIATION OF GEMINAL FLUORINE-FLUORINE CHEMICAL-SHIFT DIFFERENCES WITH TEMPERATURE.
Abstract
The temperature dependence of the geminal fluorine-fluorine chemical-shift differences in a variety of unsymmetrically substituted cyclobutanes is interpreted in terms of a classical equilibrium between axial and equatorial conformations. With the assumption that the conformations have the same entropy, freeenergy differences between the conformers are calculated and discussed. The axial conformer in monosubstituted cyclobutanes may be nearly planar. The absence of temperature effects in the spectra of a cyclobutene and a cyclobutanone indicates that these systems are statically planar. The angle of puckering of 1,1-difluoro3-phenylcyclobutane is calculated by the dipolemoment method to be about 27 deg. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1965
- Accession Number
- AD0463482
Entities
People
- John D. Roberts
- Joseph B. Lambert
Organizations
- California Institute of Technology