On the Beckmann rearrangement of ketoximes: A kinetic study in trifluoromethanesulfonic acid

The formation and the destruction of an intermediate involved in the Beckmann rearrangement of 2,4,6‐trimethylacetophenone oxime have been studied in concentrated trifluoromethanesulfonic acid by kinetic and spectroscopic measurements. Observed (kobs) and thermodynamic rate constants (ko) have been...

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Bibliographic Details
Published in:International journal of chemical kinetics 2004-08, Vol.36 (8), p.417-426
Main Authors: Marziano, N. C., Ronchin, L., Tortato, C., Tonon, O., Bertani, R.
Format: Article
Language:English
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Summary:The formation and the destruction of an intermediate involved in the Beckmann rearrangement of 2,4,6‐trimethylacetophenone oxime have been studied in concentrated trifluoromethanesulfonic acid by kinetic and spectroscopic measurements. Observed (kobs) and thermodynamic rate constants (ko) have been estimated and the values compared with the ones obtained in perchloric, sulfuric, and methanesulfonic acids. In the range 80–100 wt% of sulfuric acid, combined analysis of kobs and ko rates shows a specific catalysis due to [H2SO4] species. In trifluoromethanesulfonic acid, lower rate constants, compared to the values in sulfuric acid, have been observed which differ at 99 wt% by a factor of 103 ca. The catalytic effect of different strong acids, the structure of the intermediate inferred from Raman and NMR spectra, and the role of the ion‐pairs involved in the reaction are discussed. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 417–426, 2004
ISSN:0538-8066
1097-4601
DOI:10.1002/kin.20011