Accession Number : AD0463482


Title :   NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY. CONFORMATIONAL PROPERTIES OF CYCLOBUTANES: VARIATION OF GEMINAL FLUORINE-FLUORINE CHEMICAL-SHIFT DIFFERENCES WITH TEMPERATURE.


Descriptive Note : Technical rept.,


Corporate Author : CALIFORNIA INST OF TECH PASADENA GATES AND CRELLIN LABS OF CHEMISTRY


Personal Author(s) : Lambert, Joseph B ; Roberts, John D


Report Date : May 1965


Pagination or Media Count : 1


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)


Descriptors :   *DIPOLE MOMENTS , MOLECULAR PROPERTIES , CYCLOBUTANES , FLUORINE COMPOUNDS , HALOGENATED HYDROCARBONS , MOLECULAR STRUCTURE , NUCLEAR MAGNETIC RESONANCE , NITRATES , AROMATIC COMPOUNDS , KETONES , CHLORINE COMPOUNDS , POLARIZATION , CHEMICAL BONDS , MOLECULAR ISOMERISM , SYNTHESIS(CHEMISTRY) , TEMPERATURE


Distribution Statement : APPROVED FOR PUBLIC RELEASE