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On the Beckmann rearrangement of ketoximes: A kinetic study in trifluoromethanesulfonic acid
β Scribed by N. C. Marziano; L. Ronchin; C. Tortato; O. Tonon; R. Bertani
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 142 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0538-8066
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β¦ Synopsis
Abstract
The formation and the destruction of an intermediate involved in the Beckmann rearrangement of 2,4,6βtrimethylacetophenone oxime have been studied in concentrated trifluoromethanesulfonic acid by kinetic and spectroscopic measurements. Observed (k~obs~) and thermodynamic rate constants (k^o^) have been estimated and the values compared with the ones obtained in perchloric, sulfuric, and methanesulfonic acids. In the range 80β100 wt% of sulfuric acid, combined analysis of k~obs~ and k^o^ rates shows a specific catalysis due to [H~2~SO~4~] 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 10^3^ ca. The catalytic effect of different strong acids, the structure of the intermediate inferred from Raman and NMR spectra, and the role of the ionβpairs involved in the reaction are discussed. Β© 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 417β426, 2004
π SIMILAR VOLUMES
The kinetics of the rearrangement of 3,4-di-O-benzyl-l,Z-n-(1-methoxyethylid~ne)-~-L-rhamnopy~~nose to methyl 2-O-acetyl-3.4-di-O-bcnzyl-tu-L-rhamnopyranoside with a catalytic amount of 1 ,I .3,3,-tctralnethylurea-trifluoromethanesulfonic acid in deuterated chloroform was studied by 'H-n.m.r. spectr