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Beckmann rearrangement ppt

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Beckmann rearrangement ppt

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Beckmann rearrangement ppt

  1. 1. Beckmann Rearrangement Persented by Dinesh yadav 2017PCY5358 1 Submitted to:- Dr. Ragini Gupta Prof.&HOD Dept. of Chemistry
  2. 2. Beckmann rearrangement • The acid-catalysed conversion of ketoximes to amides is known as the Beckmann rearrangement • The Beckmann rearrangement, named after the German chemist Ernst Otto Beckmann (1853–1923) • This rearrangement is occurs in both cyclic and acyclic compounds . • Aldoximes are less reactive. • Cyclic oximes yield lactams and acyclic oximes yield amides 2J. Am. Chem. Soc., 1924, 46 (6), pp 1477–1483 DOI: 10.1021/ja01671a018
  3. 3. Beckmann rearrangement 3 Reagents:- Conc.H2SO4, HCl, PCl5, PCl3, SOCl2, ZnO, SiO2, PPA (Poly phosphoric acid) etc., are commonly employed in Beckmann rearrangement. Oxime Amide J. Am. Chem. Soc., 1924, 46 (6), pp 1477–1483 DOI: 10.1021/ja01671a018
  4. 4. Reaction mechanism The first step in the process is formation of an oxime from the aldehyde or ketone, 4
  5. 5. Reaction mechanism 5 This rearrangement take place an alkyl migration with expulsion of the hydroxyl group to form a nitrilium ion followed by hydrolysis.
  6. 6. Migratory aptitude • The relative migratory aptitudes of different groups in Beckmann rearrangement is illustrated below. 6
  7. 7. Applications in drug synthesis:- • An alternative industrial synthesis method for Paracetamol. It is involves direct acylation of phenol with acetic anhydride catalyzed by HF, conversion of the ketone to a ketoxime with hydroxylamine, followed by the acid-catalyzed Beckmann rearrangement to give the amide 7 Paracetamol
  8. 8. Applications in drug synthesis:- • The Beckmann rearrangement is also used in the synthesis of 1. DHEA 2. Benazepril 3. Etazepine etc. 8
  9. 9. Applications in polymer synthesis:- • Beckmann rearrangement can be rendered catalytic using cyanuric chloride and zinc chloride as a co-catalyst. For example, cyclododecanone can be converted to the corresponding lactam, the monomer used in the production of Nylon 12 9
  10. 10. Applications in polymer synthesis:- • The Beckmann rearrangement is also used in the synthesis of Nylon 6 10
  11. 11. THANK YOU. 11

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