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Beckmann rearrangement of acetophenone oximes to the corresponding amides organo-catalyzed by trifluoroacetic acid for sustainable NSAIDs synthesis

Paper ID Volume ID Publish Year Pages File Format Full-Text
39801 45836 2014 11 PDF Available
Title
Beckmann rearrangement of acetophenone oximes to the corresponding amides organo-catalyzed by trifluoroacetic acid for sustainable NSAIDs synthesis
Abstract

•High yield of acetaminophen and acetanilide is obtained under mild conditions.•Easy Beckmann rearrangement, easy recovery of the reagents, no work-up operation.•A sustainable process can be implemented since TFA is recycled in high extent.•TFA acts as an organocatalyst, Brønsted acid catalysis is not verified.•The key step of the mechanism is the exchange of the trifluoroacetyl group.

The Beckmann rearrangement of acetophenone oximes to the corresponding amides (4-hydroxyacetophenone oxime to N-acetyl-4-hydroxyacetanilide and acetophenone oxime to N-phenylacetamide) is investigated by using trifluoroacetic acid (TFA) as catalyst. The reaction occurs either in the presence or in the absence of a suitable solvent. High selectivity and practically quantitative yield to amide is achieved in both cases at TFA/substrate > 3. Both TFA and the solvent (whenever present) could be easily reused by distillation since no protonation of amides occurs. The reaction proceeds via a multistep reaction path and the role of TFA is related not only to its acidity but also mainly to its ability on forming reactive trifluoroacetylated intermediates. In particular, the highly reactive trifluoroacetylated amide is actually the effective catalyst. Finally, a likely reaction path is proposed.

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Keywords
Trifluoroacetic acid; Organocatalysis; Beckmann rearrangement; Acetaminophen
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Beckmann rearrangement of acetophenone oximes to the corresponding amides organo-catalyzed by trifluoroacetic acid for sustainable NSAIDs synthesis
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 472, 22 February 2014, Pages 167–177
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us