Unequal primary kinetic isotope effects in the base-catalysed H–D exchange of diastereotopic protons
作者:
Robert R. Fraser,
Philippe J. Champagne,
期刊:
Canadian Journal of Chemistry
(NRC Available online 1980)
卷期:
Volume 58,
issue 1
页码: 72-78
ISSN:0008-4042
年代: 1980
DOI:10.1139/v80-012
出版商: NRC Research Press
数据来源: NRC
摘要:
Primary kinetic isotope effects have been measured for the base-catalyzed exchange reaction of 4′,1″-dimethyl-1,2,3,4-dibenzcyclohepta-1,3-diene-6-one,1. It was found that the isotope effectskH/kTandkD/kTfor the faster exchanging protons (13.6 and 3.8 respectively) are significantly larger than the corresponding values for the slower exchanging protons (4.6 and 1.6 respectively). These differences could result from truly unequal isotope effects due to transition state differences or intrusion of a second pathway for exchange of the less reactive proton in the dedeuteration reaction. The data appear to support the latter interpretation. The secondary deuterium isotope effect was found to be 1.18.
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