Kinetics and mechanism of the Beckmann rearrangement of acetophenone oximes in sulphuric acid
- 1 January 1970
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society B: Physical Organic
- p. 338-346
- https://doi.org/10.1039/j29700000338
Abstract
The kinetics of the Beckmann rearrangement of acetophenone oximes have been measured over the acidity range 70–98% sulphuric acid. A study of the rearrangement of ortho-substituted acetophenone oximes has shown that an N-arylnitrilium ion is an intermediate in the rearrangement. Comparison of the rates of the rearrangement of 2,4,6-trimethylacetophenone oxime in sulphuric and perchloric acids indicates that the reactive species in concentrated sulphuric acid (>70%) is the oxime O-sulphonic acid. Isotopic labelling experiments have shown that the migration of the oxygen function is intermolecular. The transition state of the rearrangement is postulated to be a phenonium ion in which the leaving oxygen function is still partially bonded to the nitrogen atom.Keywords
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