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13 C spin‐lattice relaxation study of chlorinated alkanes
Author(s) -
Pitkänen Maija,
Laihia Katri,
Velichko F. K.,
Lavrukhin B. D.
Publication year - 1987
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/mrc.1260250811
Subject(s) - chemistry , solvent , molecule , dipole , relaxation (psychology) , computational chemistry , organic chemistry , psychology , social psychology
The spin‐lattice relaxation of ten polychloroalkanes (ethanes to pentanes) have been studied both neat and in a 50% solution in CDCl3. The T 1 values for the CH 2 , CH 2 Cl and CHCl 2 carbons decrease with increasing molecular weight in accordance with a dipolar‐dominated mechanism, whereas those of the CCl3 carbons showed no dependence on molecular weight. In chloropentanes, with chlorine substitution at one end only, the frequency of segmental motion begins to compete with that of overall tumbling of the molecule. Consequently, the T 1 minimum is shifted from the middle towards the heavier end of the molecule, and also a relatively large T 1 for the terminal methyl is observed. It was also demonstrated that the segmental motion is less dependent on solvent and concentration (viscosity) than the overall reorientation of the molecules.