The Fischer–Hepp rearrangement is a
rearrangement reaction
In organic chemistry, 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 ...
in which an
aromatic
In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...
N-nitroso or
nitrosamine
In organic chemistry, nitrosamines (or more formally ''N''-Nitrosamines) are organic compounds with the chemical structure , where R is usually an alkyl group. They feature a nitroso group () bonded to a deprotonated amine. Most nitrosamines are ...
converts to a carbon
nitroso
In organic chemistry, nitroso refers to a functional group in which the nitric oxide () group is attached to an organic moiety. As such, various nitroso groups can be categorized as ''C''-nitroso compounds (e.g., nitrosoalkanes; ), ''S''-nitroso ...
compound:
This
organic reaction
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, Mechanistic Organ ...
was first described by the German chemist
Otto Philipp Fischer (1852–1932) and
Eduard Hepp (June 11, 1851 – June 18, 1917)
[W Pötsch. ''Lexikon bedeutender Chemiker'' (VEB Bibliographisches Institut Leipzig, 1989) ] in 1886, and is of importance because
para
Para, or PARA, may refer to:
Businesses and organizations
* Paramount Global, traded as PARA on the Nasdaq stock exchange
* Para Group, the former name of CT Corp
* Para Rubber, now Skellerup, a New Zealand manufacturer
* Para USA, formerly ...
-
NO secondary
aniline
Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine
In organic chemistry, an aromatic amine is an organic compound consisting of an aroma ...
s cannot be prepared in a direct reaction.
The
rearrangement reaction
In organic chemistry, 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 ...
takes place by reacting the
nitrosamine
In organic chemistry, nitrosamines (or more formally ''N''-Nitrosamines) are organic compounds with the chemical structure , where R is usually an alkyl group. They feature a nitroso group () bonded to a deprotonated amine. Most nitrosamines are ...
precursor with
hydrochloric acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid
Acid strength is the tendency of an acid, symbol ...
. The
chemical yield
In chemistry, yield, also referred to as reaction yield, is a measure of the quantity of moles of a product formed in relation to the reactant consumed, obtained in a chemical reaction, usually expressed as a percentage. Yield is one of the pri ...
is generally good under these conditions, but often much poorer if a different
acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
is used. The exact
reaction mechanism
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs.
A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of ...
is unknown but there is evidence suggesting an
intramolecular reaction Intramolecular in chemistry describes a process or characteristic limited within the structure of a single molecule, a property or phenomenon limited to the extent of a single molecule.
Examples
* intramolecular hydride transfer (transfer of a hy ...
.
Sources
''Named Things in Chemical Industry''
See also
*
Friedel–Crafts alkylation-like reactions:
**
Hofmann-Martius rearrangement
**
Fries rearrangement
The Fries rearrangement, named for the German chemist Karl Theophil Fries, is a rearrangement reaction of a phenolic ester to a hydroxy aryl ketone by catalysis of Lewis acids.
It involves migration of an acyl group of phenol ester to the aryl ...
References
{{DEFAULTSORT:Fischer-Hepp Rearrangement
Rearrangement reactions
Name reactions