th  - 1988 - 51st ENC Conference

1 I~ I SOLID PHASE CARBON-13 NMR STUDIES OF CROWN ETHERS AND THEIR
COMPLEXES. G.W. Buchanan*, C. Morat and R.A. Kirby, Ottawa-Carleton Chemistry
Institute, Dept. of Chemistry, Carleton University, Ottawa Canada KIS 586.
C.I. Ratcliffe and J.A. Ripmeester, Chemistry Division, N.R.C. Ottawa Canada KIA ORg.
For a series of 12-crown-4, 14-crown-4 and 18-crown-6 ethers, i~C CPMAS spectra
have been used to determine the asymmetric units present in the crystals. Results
are compared wfth those available from x-ray crystallographic data. In several
18-crown-6 complexes, low temoerature spectra have been recorded which reflect
retardation, on the NMR timescale, of rotational motion oresent in the solids at
298K. Torsional angle contributions to the observed 13C chemical shifts at low
temperature will be delineated.
I
-- 2 I A NEW APPROACH FOR QUANTITATIVE 13C-NMR SPECTROSCOPY OF COALt:
Robert E. Botto*, John V. Muntean and Leon M. Stock, Chemistry Division, Argonne
National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439.
Several researchers recently have discussed the scope and limitations of solid
13C-NMR spectroscopy for the analysis of fossil fuels. Several, including our-
selves, have established that only 50-70% of the 13C nuclei in coals are observed
in Bloch-decay or CP/MAS solid NMR experiments. This poster concerns recent work
from our laboratories directed toward the achievement of more quantitative
spectroscopic results. One phase of our work centers on the use of tetrakis(tri-
methylsilyl)silane as a qualitative chemical shift standard and as a quantitative
internal standard for the measurement of the observable quantity of 13C nuclei.
The other phase of this study focuses on the application of samarium(ll) iodide
for the selective removal of organic free radicals from coal. Reduction of the
radical content is essential for the realization of quantitative spectroscopic
results.
tWork performed under the auspices of the Office
Sciences, Division of Chemical Sciences, U.S. Department
contract number W-31-I09- ENG-38.
98
of Basic Energy
of Energy, under