why sodium ethoxide is used in neber rearrangement reaction
Answers
The Neber rearrangement is an organic reaction in which a ketoxime is converted into an alpha-aminoketone via a rearrangement reaction.
The oxime is first converted to an O-sulfonate, for example a tosylate by reaction with tosyl chloride. Added base forms a carbanion which displaces the tosylate group in a nucleophilic displacement to an azirine and added water subsequently hydrolyses it to the aminoketone.
The Beckmann rearrangement is a side reaction.
Answer:
The transformation of a ketoxime O-arylsulfonate into an α-amino ketone involving the deprotonation of an αmethylene hydrogen by a base and the subsequent acidic hydrolysis of the resulting azirine intermediate is generally referred to as the Neber rearrangement. This rearrangement is generally carried out in ethanol by treatment of the ketoxime tosylate with sodium ethoxide, followed by the acidic hydrolysis. The present study represents some of the features of this rearrangement with a particular emphasis to 2,4-dinitrophenylacetone and found even a weak base, like pyridine, is enough to trigger the rearrangement. This reaction has general application in the preparation of α-amino ketones.