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Proton relaxation NMR study of polycrystalline progesterone

✍ Scribed by E.R. Andrew; K. Jurga; J.M. Radomski; E.C. Reynhardt

Publisher
Elsevier Science
Year
1992
Tongue
English
Weight
368 KB
Volume
1
Category
Article
ISSN
0926-2040

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✦ Synopsis

Polycrystalline progesterone (4-pregnene-3,20-dione, C21H30O2) has been investigated by proton NMR methods between 80 and 350 K. A reduction in dipolar second moment is ascribed to methyl group reorientation. Minima in the spin-lattice relaxation time found in measurements at five frequencies from 7 to 200 MHz are attributed to reorientation of two of the three methyl groups in each molecule, characterized by activation energy Ea = 10.9 +/- 0.8 kJ/mol and tau o = (2.3 +/- 0.2) x 10(-13) s. Additional relaxation at lower temperatures is attributed to reorientation of the third methyl group with Ea approximately 3.4 kJ/mol. Measurements were also made of relaxation in the rotating frame.

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