Deuterium and carbon-13 NMR of the solid polymorphism of benzenehexoyl hexa-n-hexanoate
Deuterium and carbon-13 NMR of specifically labeled benzenehexoyl hexa-n-hexanoate in the various solid-state phases are reported. The spectra exhibit dynamic line shapes which change discontinuously at the phase transitions. The results are interpreted in terms of sequential melting of the side chains on going from the low-temperature solid phases IV, III, etc., toward the liquid. In phase IV the molecules are very nearly static, except for fast rotation of the methyl groups about their C/sub 3/ axes. The results in phase III were quantitatively interpreted in terms of a two-site isomerization process involving simultaneous rotation by 95/sup 0/ about C/sub 1/-C/sub 2/ and transition from gtg to g'g't (or equivalently g'tg' to ggt) for the rest of the chain. The specific rate of this reaction at 0/sup 0/C is approx. 10/sup 5/s/sup -1/. In phase II additional chain isomerization processes set-in which were, however, not analyzed quantitatively. Further motional modes, involving reorientation of whole chains about their C/sup ar/-O bonds, appear on going to phase I. In all solid phases the benzene ring remains static.
- Research Organization:
- Weizmann Institute of Science, Rehovot, Israel
- OSTI ID:
- 5736490
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:24; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Reorientational motions of NH/sub 2/ groups in potassium amide
High-pressure studies to determine the effects of volume and temperature on the lattice dynamics of molecular solids: N/sub 2/, CO/sub 2/, CH/sub 4/. Final report for period July 1, 1979-August 31, 1981
Related Subjects
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
AROMATICS
CARBON 13
CARBON ISOTOPES
CHEMICAL REACTIONS
DATA
DEUTERIUM
DEUTERIUM COMPOUNDS
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
ISOMERIZATION
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
LOW TEMPERATURE
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHASE STUDIES
RESONANCE
SOLIDS
SPECTRA
STABLE ISOTOPES