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Investigation of the thermal isomerization of 1α,25‐dihydroxycholecalciferol by nuclear magnetic resonance spectroscopy
Author(s) -
Grant Anne,
Bhattacharyya Pranab K.
Publication year - 1983
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550150405
Subject(s) - chemistry , isomerization , kinetics , nuclear magnetic resonance spectroscopy , spectroscopy , resonance (particle physics) , chemical kinetics , impurity , photochemistry , thermal , stereochemistry , thermodynamics , catalysis , organic chemistry , atomic physics , quantum mechanics , physics
This investigation of the kinetics and thermodynamics of the thermal isomerization reaction of 1α,25‐dihydroxycholecalciferol, the physiologically active metabolite of vitamin D 3 , is based on the simultaneous determinations of 1α,25‐(OH) 2 D 3 and its previtamin analog by nuclear magnetic resonance spectroscopy which distinguishes these compounds from possible impurities. The kinetics at different temperatures are used to obtain the activation parameters for the sigmatropic [1,7] thermal interconversion process which is shown to be compatible with a reaction that is unimolecular and concerted. The nature of the transition state of the activated complex, the reaction energetics, and the relative stabilities of 1α,25‐(OH) 2 D 3 and vitamin D 3 are discussed.