Question

Rearrangement of an oxime to an amide in the presence of a strong acid is called

Answer 1

Hint: We know that,one example of functional group is imine whose formula is \[{\rm{C}} = {\rm{N}}\] .The oxime is an organic compound that belongs to the class of imines. The chemical formula to reprsent oxime is \[{{\rm{R}}_{\rm{1}}}{{\rm{R}}_2}{\rm{C}} = {\rm{NOH}}\] . Here, \[{{\rm{R}}_{\rm{1}}}\] indicates an alkyl group and \[{{\rm{R}}_2}\] represents a hydrogen atom.

Complete Step by Step Solution:
Let's understand what an amide is. An amide is a functional group of the formula \[{\rm{R}} - {\rm{CO}} - {\rm{N}}{{\rm{H}}_{\rm{2}}}\] . When a molecule of ammonia is added to a carboxylic acid, an amide is formed.

Let's understand the Beckmann rearrangement in detail. In this reaction, an oxime is converted into an amide in an acidic medium. Let's understand the mechanism of the reaction in detail.

In the first step, a proton is accepted by the oxygen atom of the oxime. Then, the water molecule separates and a proton is accepted by the nitrogen atom. In the third step, a nucleophilic attack of the Oxygen atom of the water molecule at the carbocation takes place. In the fourth step, deprotonation occurs and alcohol forms. In the last step, rearrangement of hydrogen atoms occurs which results in the formation of an amide.

Image: Beckmann Rearrangement

Hence, the rearrangement of an oxime to amide in an acidic medium is called Beckmann rearrangement.

Note: It is to be noted that, the imine functional group is considered a Schiff's base if the group bonded to the N atom is not an atom of Hydrogen. The preparation of imine is done by the reaction of a ketone, an aldehyde and hydroxylamine.