This document summarizes various types of rearrangement reactions in organic chemistry. It describes 15 categories of rearrangements including rearrangements to electron deficient carbons, nitrogens, and oxygens. For each category, 1-2 specific rearrangements are explained in more detail, including their mechanisms. Rearrangements discussed include the Wagner-Meerwein, Pinacol, Benzilic acid, Hofmann, Curtius, Lossen, Beckmann, Baeyer-Villiger, Stevens, Sommelet-Hauser, Wittig, Favorskii, Benzidine, Fries, and Claisen rearrangements. The document was prepared by a student as part of their coursework to provide an overview of

1. Rearrangement reactions
Prepared by- Mohamad Haider
Department of Pharmaceutical Chemistry, DIPSAR
Roll no.- 04/MPH/DIPSAR/19

2. Introduction
• A rearrangement reaction is a broad class of
organic reactions where the carbon skeleton of a
molecule is rearranged to give a structural
isomer of the original molecule. Often a
substituent moves from one atom to another
atom in the same molecule.
• Generally the migrating group never leaves the
molecule

3. Classification
1.Rearrangement to Electron Deficient Carbon
• Wagner-Meerwein Rearrangement
• Pinacol Rearrangement
• Benzilic Acid Rearrangement
• Arndt-Eistert Homologation Reaction
2. Rearrangement to Electron Deficient Nitrogen
• Hofmann Rearrangement
• Curtius Rearrangement
• Schmidt Rearrangement
• Lossen Rearrangement
• Beckmann Rearrangement

4. 3. Rearrangement to Electron Deficient Oxygen
• Baeyer Villiger Reaction
• Dakin Reaction
4. Rearrangement to Electron-Rich Carbon
• Stevens Rearrangement
• Sommelet-Hauser Rearrangement
• Wittig Rearrangement
• Favorskii Rearrangement
5. Aromatic Rearrangements
• Benzidine Rearrangement
• Fries Rearrangement
• Claisen Rearrangement

5. Wagner-Meerwein Rearrangement
• It is one of the simplest systems where an alkyl
group migrates, with its bonding pair, to an
electron-deficient carbon atom
• Mechanism:

6. Pinacol Rearrangement
• Treatment of 1,2-diols (pinacol) with acid lead to
rearrangement to give ketone.
• Mechanism:

7. Benzilic Acid Rearrangement
• Reaction of 1,2-diketones into a-hydroxy
carboxylic acids using base is Benzilic acid
rearrangement.
•

8. Arndt-Eistert Homologation Reaction
• This involves a series of chemical reactions that
synthesise a carboxylic acid from it’s homologue
with one fewer carbon atoms.
• Mechanism:

9. Hofmann Rearrangement
• This rearrangement provides an effective
method for the synthesis of primary aliphatic
and aromatic amines from primary amides.
• Mechanism

10. Lossen Rearrangement
• The Lossen rearrangement is the conversion of
a hydroxamic acid to an isocyanate (via the
formation of an intermediate).The isocyanate
can be used further to generate amines in the
presence of H2O:

11. Curtius Rearrangement
• The Cartius rearrangement is the thermal
decomposition of an acyl azide to an isocyanate
with loss of nitrogen gas.
• The isocyanate then undergoes attack by water
to yield primary amine.

12. Schmidt Rearrangement
• The reaction is closely related to Cartius reaction
except that the acyl azide is produced by reaction of
carboxylic acid with hydrazoic acid. The reaction is
acid catalysed.
• The acyl azide then undergoes the same reaction as
in Cartius rearrangement to form primary amine.

13. Beckmann Rearrangement
• The acid-catalyzed conversion of an oxime into
an amide is known as Beckmann rearrangement:
• Mechanism

14. Baeyer Villiger Reaction
• It is an organic reaction that forms an ester from
a ketone or a lactone from a cyclic ketone, using
peroxyacids or peroxides as the oxidant.
• Mechanism

15. Dakin Reaction
• It is an organic reaction in which an ortho- or para-
hydroxylated phenyl aldehyde or ketone reacts with
hydrogen peroxide in base to form a benzenediol.
• Mechanism

16. Stevens Rearrangement
• It is an organic reaction converting quaternary
ammonium salts and sulfonium salts to the
corresponding amines or sulfides in presence of a
strong base:
• Mechanism

17. Sommelet-Hauser Rearrangement
• It is a rearrangement reaction of certain benzyl
quaternary ammonium salts. The reagent is
usually sodium amide and the reaction product
a N-dialkyl benzyl amine (with a new alkyl
group in the aromatic ortho position).

18. Wittig Rearrangement
• The [1,2]-Wittig Rearrangement is the base-
promoted reaction of ethers to yield secondary
or tertiary alcohol:
• Mechanism

19. Favorskii Rearrangement
• It is a rearrangement reaction of α-haloketones.
Particularly useful for ring contraction.
• Mechanism

20. Benzidine Rearrangement
• Treatment of 1,2-diphenylhydrazine with mineral
acids induces a rearrangement reaction to 4,4'-
benzidine. This is benzidine rearrangement.
• Mechanism

21. Fries Rearrangement
• It is a rearrangement reaction of a phenolic ester to
a hydroxy aryl ketone by catalysis of Lewis acids.
• Mechanism

22. Claisen Rearrangement
• It is a [3,3]-sigmatropic reaction where an Aryl
allyl ethers on being heating converts into
allylphenols.
• Mechanism

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