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14 N NMR spectroscopy of tertiary amines in supercritical fluids
Author(s) -
Gaemers S.,
Elsevier C. J.
Publication year - 2000
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/1097-458x(200008)38:8<650::aid-mrc705>3.0.co;2-u
Subject(s) - chemistry , supercritical fluid , benzene , nuclear magnetic resonance spectroscopy , viscosity , solvent , proton nmr , analytical chemistry (journal) , organic chemistry , thermodynamics , physics
The linewidths of 14 N NMR resonances of tertiary amines and nitrogen‐containing heterocycles were studied in liquefied gases and supercritical fluids. Owing to a lower rotational correlation time of the solutes in the low‐viscosity fluids, the 14 N NMR linewidths were smaller than those in benzene solutions, but to a lesser extent than theoretically achievable based on the relative solvent viscosities. The discrepancy is attributed to the free rotor correlation time, which contributes considerably to the rotational correlation time at high temperatures and low viscosities. The use of liquid CO 2 gives better results than supercritical CO 2 . Copyright © 2000 John Wiley & Sons, Ltd.