Simple aromatic ring

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Simple aromatic rings, also known as simple arenes or simple aromatics, are aromatic organic compounds that consist only of a conjugated planar ring system.[ citation needed ] Many simple aromatic rings have trivial names. They are usually found as substructures of more complex molecules ("substituted aromatics"). Typical simple aromatic compounds are benzene, indole, and pyridine. [1] [ page needed ] [2] [ page needed ]

Contents

Simple aromatic rings can be heterocyclic if they contain non-carbon ring atoms, for example, oxygen, nitrogen, or sulfur. They can be monocyclic as in benzene, bicyclic as in naphthalene, or polycyclic as in anthracene. Simple monocyclic aromatic rings are usually five-membered rings like pyrrole or six-membered rings like pyridine. Fused bicyclic molecules consist of two rings that are connected by shared edges.[ clarification needed ]

Heterocyclic aromatic rings

Table of simple aromatic rings
Five-membered ringsFused five-membered rings with six-membered rings
Pyrrole structure.png
Pyrrole
Indole structure.png
Indole
Carbazol - Carbazole.svg
Carbazole
Furan structure.png
Furan
Benzofuran structure.png
Benzofuran
Dibenzofuran - Dibenzofuran.svg
Dibenzofuran
Thiophene structure.png
Thiophene
Benzothiophene structure.png
Benzothiophene
Dibenzothiophen - Dibenzothiophene.svg
Dibenzothiophene
Imidazole structure.png
Imidazole
Benzimidazole structure.png
Benzimidazole
Purine structure.png
Purine
Pyrazole structure.png
Pyrazole
Indazol.svg
Indazole
 
Oxazole structure.png
Oxazole
Benzoxazole structure.png
Benzoxazole
 
Thiazole structure.png
Thiazole
Benzothiazole structure.png
Benzothiazole
 
1,2,3-Triazole structure.svg
1,2,3-Triazole
1,2,4-Triazole structure.svg
1,2,4-Triazole
 
Six-membered ringsFused six-membered rings with six-membered rings
Benzene-Kekule-2D-skeletal.png
Benzene
Naphthalene-2D-Skeletal.svg
Naphthalene
Anthracene structure.png
Anthracene
Pyridine structure.png
Pyridine
Quinoline structure.png
Quinoline
Acridin.svg
Acridine
Pyrazine structure.png
Pyrazine
Quinoxaline structure.png
Quinoxaline
Phenazine.png
Phenazine
Pyrimidine structure.png
Pyrimidine
Quinazoline structure.png
Quinazoline
Pteridin - Pteridine.svg
Pteridine
Pyridazine structure.png
Pyridazine
Cinnoline structure.png
Cinnoline
Phthalazin - Phthalazine.svg
Phthalazine
1,2,3-Triazin - 1,2,3-triazine.svg
1,2,3-Triazine
1,2,4-Triazin - 1,2,4-triazine.svg
1,2,4-Triazine
1,3,5-Triazin - 1,3,5-triazine.svg
1,3,5-Triazine

The nitrogen (N)-containing aromatic rings can be separated into basic aromatic rings that are easily protonated, and form aromatic cations and salts (e.g., pyridinium), and non-basic aromatic rings.

In the oxygen- and sulfur-containing aromatic rings, one of the electron pairs of the heteroatoms contributes to the aromatic system (similar to the non-basic nitrogen-containing rings), whereas the second lone pair extends in the plane of the ring (similar to the primary nitrogen-containing rings).

Criteria for aromaticity

In contrast, molecules with 4n pi electrons are antiaromatic.

See also

References

  1. Clayden, J.; Greeves, N.; Warren, S.; Wothers, P. (2001). Organic Chemistry . Oxford, Oxfordshire: Oxford University Press. ISBN   0-19-850346-6.
  2. Eicher, T.; Hauptmann, S. (2003). The Chemistry of Heterocycles: Structure, Reactions, Syntheses, and Applications (2nd ed.). Wiley-VCH. ISBN   3-527-30720-6.