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13C spin-lattice relaxation study of chlorinated alkanes

✍ Scribed by Maija Pitkänen; Katri Laihia; F. K. Velichko; B. D. Lavrukhin

Publisher
John Wiley and Sons
Year
1987
Tongue
English
Weight
309 KB
Volume
25
Category
Article
ISSN
0749-1581

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✦ Synopsis

The spin-lattice relaxation of ten polychloroalkanes (ethanes to pentanes) have been studied both neat and in a 50% solution in CDC13. The Tl values for the CH,, CH,Cl and CHCl, carbons decrease with increasing molecular weight in accordance with a dipolar-dominated mechanism, whereas those of the CCl, 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 Tl minimum is shifted from the middle towards the heavier end of the molecule, and also a relatively large Tl 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. KEY WORDS 13C Relaxation of chlorinated aliphatics 13C Spin-lattice relaxation of polychloroalkanes.

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