Schmidt Reaction refers to an organic chemical reaction wherein azides are reacted with the carbonyl group of a compound to give rise to amines or amides. This reaction was first reported by Karl Friedrich Schmidt in 1924.
Schmidt Reaction Examples
The Schmidt Reaction can be employed to either get amides by reacting the azide with a ketone, or to get an amine by reacting the azide with a carboxylic acid.
Schmidt Reaction for Carboxylic Acids
The chemical reaction wherein amines can be produced from an azide and a carboxylic acid can be illustrated as follows:
Schmidt Reaction for Ketones
Another example of the Schmidt Reaction is when an amide is produced from the chemical reaction between an azide and a ketone. This reaction can be illustrated as follows:
The Schmidt reaction can be used to prepare benzanilide from benzophenone and hydrogen azide. This is an example of the preparation of an amide from a ketone and an azide.
Schmidt Reaction Mechanism
As discussed earlier, the schmidt reaction can be used to produce either amides or amines. For each of these products, a different functional group is required (ketones and carboxylic acids respectively). Therefore, the mechanisms for each of these reactions are detailed below.
Schmidt Reaction Mechanism for Producing Amines
- This mechanism begins with the formation of an acylium ion from the protonation of the carboxylic acid followed by the removal of water.
- This acylium ion is now reacted with hydrazoic acid, leading to the formation of a protonated azido ketone.
- Now, the protonated azido ketone and the R group undergo a rearrangement reaction, resulting in the migration of the carbon-nitrogen bond and the removal of dinitrogen leading to the formation of a protonated isocyanate.
- Now, a carbamate is formed when water is introduced to attack the protonated isocyanate.
- The carbamate is now deprotonated. The subsequent removal of CO2 yields the required amine.
This mechanism can be illustrated as follows:
Schmidt Reaction Mechanism for Producing Amides
- This Mechanism begins with the protonation of the ketone, leading to the formation of an O-H bond.
- The subsequent nucleophilic addition of the azide leads to the formation of an intermediate.
- Water is now removed from this intermediate via an elimination reaction, forming a temporary imine.
- An alkyl group which was a part of the original ketone now migrates from the carbon to the nitrogen belonging to the imine. This results in the elimination of dinitrogen.
- Now, water is used to attack the resulting compound, and the subsequent deprotonation yields a tautomer of the required amide.
- The relocation of a proton belonging to the tautomer of the amide gives the final amide product.
Frequently Asked Questions – FAQs
What is Schmidt rearrangement?
Schmidt reactions refer to acid-catalyzed hydrazoic acid reactions of electrophiles, such as carbonyl compounds, tertiary alcohols and alkenes. To include amines, nitriles, amides or imines, these substrates undergo rearrangement and extrusion of nitrogen.
What is reformatsky reaction explain?
The Reformatsky reaction (sometimes pronounced Reformatskii reaction) is an organic reaction that uses metallic zinc to form β-hydroxy-esters to condense aldehydes or ketones with al-halo esters. By treating an alpha-halo ester with zinc dust, the organozinc reagent, also called a ‘Reformatsky enolate’, is prepared.
Which reaction involves migration of group from carbon to nitrogen?
The Schmidt reaction involves alkyl migration with nitrogen expulsion over the chemical bond of carbon-nitrogen in an azide. The Schmidt reaction of carboxylic acid begins with the acylium ion derived from protonation and water loss.
In which medium Favorskii rearrangement occurs?
In the case of cyclic α-halo ketones, the Favorskii rearrangement constitutes a ring contraction. This rearrangement takes place in the presence of a base, sometimes hydroxide, to yield a carboxylic acid but most of the time either an alkoxide base or an amine to yield an ester or an amide, respectively.
Which type of isomers are formed in rearrangement reaction?
The products formed have the same molecular formula, but there are different structures or bonds between their atoms. Butane and isobutane, for instance, have the same number of atoms of carbon ( C) and atoms of hydrogen (H), so their chemical formulas are the same.
The Schmidt Reaction mechanism for producing amides from ketones is illustrated above.