organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

, the vicarious nucleophilic substitution is a special type of

nucleophilic aromatic substitution A nucleophilic aromatic substitution is a substitution reaction in organic chemistry in which the nucleophile displaces a good leaving group, such as a halide, on an aromatic ring. Aromatic rings are usually nucleophilic, but some aromatic compou ...

in which a

nucleophile In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...

replaces a hydrogen atom on the aromatic ring and not

leaving group In chemistry, a leaving group is defined by the IUPAC as an atom or group of atoms that detaches from the main or residual part of a substrate during a reaction or elementary step of a reaction. However, in common usage, the term is often limited t ...

s such as

halogen The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group is ...

substituents which are ordinarily encountered in S_NAr. This reaction type was reviewed in 1987 by

Polish Polish may refer to: * Anything from or related to Poland, a country in Europe * Polish language * Poles, people from Poland or of Polish descent * Polish chicken *Polish brothers (Mark Polish and Michael Polish, born 1970), American twin screenwr ...

chemists

Mieczysław Mąkosza Mieczysław Józef Mąkosza (born 16 November 1934) is a Polish chemist specializing in organic synthesis and investigation of organic mechanisms. Along with Jerzy Winiarski he is credited for the discovery of the aromatic vicarious nucleophilic ...

and

Jerzy Winiarski Jerzy is the Polish version of the masculine given name George. The most common nickname for Jerzy is Jurek (), which may also be used as an official first name. Occasionally the nickname Jerzyk may be used, which means "swift" in Polish. Peopl ...

.''Synthesis of heterocyclic compounds via vicarious nucleophilic substitution of hydrogen'' Mieczysław Mąkosza Pure Appl. Chem., Vol. 69, No. 3, pp. 559-564, 1997''
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It is typically encountered with nitroarenes and especially with nucleophiles, resulting in alkylated arenes: the new substituent can take the ''ortho'' or ''para'' positions, reversing the selectivity for the ''meta'' position that is usually observed with such compounds under electrophilic substitution. Carbon nucleophiles carry an

electron-withdrawing group In chemistry, an electron-withdrawing group (EWG) is a substituent that has some of the following kinetic and thermodynamic implications: *with regards to electron transfer, electron-withdrawing groups enhance the oxidizing power tendency of the ...

and a

: the nucleophile attacks the aromatic ring, and excess base can eliminate to form an exocyclic double bond which is successively protonated under acidic conditions, restoring

aromaticity 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 saturate ...

. :

References

{{reflist Organic reactions Name reactions