The use of two-dimensional NMR spectroscopy to determine the rates of and activation parameters for the 3,2-hydride shift
in the 2-norboryn cation
Kenneth Smith,1 Hongjun Pan,1 George Hondrogiannis,1
Andrew Mamantov,2 and Richard M. Pagni1*
1Department of Chemistry, University of Tennessee, Knoxville, TN 37996
2Environmental Protection Agency, Washington, D.C. 20460
Email:
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Dedicated to Professor Ted Sorensen on the occasion of his retirement
Abstract
Quantitative two-dimensional exchange spectroscopy has been used to determine the rates of and activation parameters for the 3,2-hydride shift in the 2-norbornyl cation. The results compare favorably with the published values obtained by line shape analysis.
Keywords: 2-Norbornyl cation, 3,2-hydride shift, EXSY, rates, activation parameters
Introduction
We recently published a paper describing the mechanism of the very unusual transformation of 2,2-dichloronorbornane into 1-chloronorbornane in a slurry of AlCl3/pentane.1 A key intermediate in the rearrangement is the 2-chloro-2-norbornyl cation which was characterized using a number of one- and two-dimensional nmr spectroscopies. The 1-chloronorbornane generated in this reaction can be used to prepare the transitory 1-norbornyl cation which can be trapped in competition to its isomerization to the well-studied 2-norbornyl cation by an unknown mechanism.2
ClClAlCl3pentaneCl+Cl
Although the 2-norbornyl cation has been well characterized by one-dimensional 1H and 13C nmr spectroscopy, it has not been, as far as we can tell, characterized by two-dimensional nmr
