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A simple method for the precise and simultaneous determination of primary and multiple secondary kinetic deuterium isotope effects in organic reactions at natural abundance
Author(s) -
Zhang BenLi,
Pionnier Sébastien
Publication year - 2001
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.362
Subject(s) - chemistry , deuterium , kinetic isotope effect , primary (astronomy) , natural abundance , abundance (ecology) , kinetic energy , isotope , computational chemistry , analytical chemistry (journal) , mass spectrometry , organic chemistry , chromatography , nuclear physics , physics , astronomy , quantum mechanics , fishery , biology
A method for the determination of kinetic isotope effects (KIEs) in organic reactions using natural abundance deuterium NMR is proposed. The method consists of the determination of the site‐specific H/D isotopic ratios of the starting reactant and the product in a reaction run under pseudo‐first‐order kinetic conditions. Using simple and easy experimental procedures, primary and/or multiple secondary KIEs can be measured simultaneously with high precision. The application of this approach to different types of reaction is described. The primary and α‐secondary KIEs for C—H(D) bond breaking of —CDH— can be measured separately. The uncertainty in the determination of small secondary KIEs can reach less than 1%. The results show that some remote secondary KIEs are not negligible. The advantages and limitations of the method are discussed. One of its merits is that the method can even be used in complex situations when there are branch reactions and when the reaction is reversible. The performance depends essentially on the signal separation in the NMR spectra. Copyright © 2001 John Wiley & Sons, Ltd.