Beckmann rearrangement ppt

Beckmann rearrangement ppt

1. Beckmann Rearrangement Persented by Dinesh yadav 2017PCY5358 1 Submitted to:- Dr. Ragini Gupta Prof.&HOD Dept. of Chemistry  

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 2 J. Am. Chem. Soc. ,  1924 ,  46  (6), pp 1477–1483 DOI:  10.1021/ja01671a018

3. Beckmann rearrangement 3 Reagents:- Conc.H 2 SO 4 , HCl , PCl 5 ,  PCl 3 , SOCl 2 , ZnO , SiO 2 , 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. Reaction mechanism The first step in the process is formation of an oxime from the aldehyde or ketone , 4

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. Migratory aptitude The relative migratory aptitudes of different groups in Beckmann rearrangement is illustrated below. 6

7. Applications in drug synthesis:- An alternative industrial synthesis method for P aracetamol .   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. Applications in drug synthesis:- The Beckmann rearrangement is also used in the synthesis of   1. DHEA 2. Benazepril 3. Etazepine etc. 8

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. Applications in polymer synthesis:- The Beckmann rearrangement is also used in the synthesis of  Nylon 6 10

11. THANK YOU. 11