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Simple aromatic ring

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	Topics Simple aromatic ring Topic Home Simple aromatic rings, also known as simple arenes or simple aromatics, are aromatic organic compoundOrganic compound An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; theref... s that consist only of a conjugatedConjugated system A chemically conjugated system is a system of atoms covalently bonded with alternating single and multiple bonds in a molecu... planar ring system with delocalizedDelocalized electron Summary In physics delocalized electrons are electrons in a molecule that are not associated with a single atom or a covalent bond.... pi electron clouds. Many simple aromatic rings have trivial names. They are usually found as substructures of more complex moleculeMolecule In chemistry, a molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds.... s ("substitutedSubstitution (chemistry) Substitution in the context of organic chemistry has the general meaning of replacing an atom, a functional group, or a sub... aromatics"). Typical simple aromatic compounds are benzeneBenzene Benzene, also known as benzol, is an organic chemical compound with the formula C6H6.... and indoleIndole Indole is an aromatic heterocyclic organic compound.... . Simple aromatic rings can be heterocyclic if they contain non-carbonCarbon Carbon is a chemical element in the periodic table that has the symbol C and atomic number 6.... ring atoms, for example, oxygenOxygen Oxygen is a chemical element with the chemical symbol O and atomic number 8.... , nitrogenNitrogen Nitrogen is a chemical element which has the symbol N and atomic number 7 in the periodic table.... , or sulfurSulfur Sulfur or sulphur is the chemical element in the periodic table that has the symbol S and atomic number 16.... . They can be monocyclic as in benzene, bicyclic as in naphthaleneNaphthalene Naphthalene is a crystalline, aromatic, white, solid hydrocarbon, best known as the primary ingredient of mothballs.... , or polycyclic as in anthraceneAnthracene In chemistry, anthracene is a solid polycyclic aromatic hydrocarbon consisting of three benzene rings derived from coal-tar.... . Simple monocyclic aromatic rings are usually five-membered rings like pyrrolePyrrole Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N.... or six-membered rings like pyridinePyridine Pyridine is a chemical compound with the formula C5H5N.... . Fused aromatic rings consist of monocyclic rings that share their connecting bonds. Heterocyclic aromatic rings The nitrogen (N)-containing aromatic rings can be separated into basic aromatic ringBasic aromatic ring Basic aromatic rings are aromatic rings in which the lone pair of electrons of a ring-nitrogen atom is not part of the aroma... s that are easily protonatedProtonation Summary Protonation is the addition of a proton to an atom, molecule, or ion.... , and form aromatic cations and salts (e.g., pyridiniumPyridinium Pyridinium refers to the cationic form of pyridine.... ), and non-basic aromatic rings. In the basic aromatic rings, the lone pairLone pair A lone pair is an electron pair without bonding or sharing with other atoms.... of electronElectron The electron is a fundamental subatomic particle that carries an electric charge.... s is not part of the aromatic system and extends in the plane of the ring. This lone pair is responsible for the basicity of these nitrogenous baseNitrogenous base Nitrogenous bases are organic compounds that owe their basic properties to the lone pair of electrons of a nitrogen atom.... s, similar to the nitrogen atom in amineAmine Amines are organic compounds and a type of functional group that contain nitrogen as the key atom.... s. In these compounds the nitrogen atom is not connected to a hydrogen atom. Examples of basic aromatic rings are pyridinePyridine Pyridine is a chemical compound with the formula C5H5N.... or quinolineQuinoline Quinoline, also known as 1-azanaphthalene, 1-benzazine, or benzo[b]pyridine, is a heterocyclic aromatic or... . Several rings contain basic as well as non-basic nitrogen atoms, e.g., imidazoleImidazole Imidazole is a heterocyclic aromatic organic compound.... and purinePurine Purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring.... . In the non-basic rings, the lone pair of electrons of the nitrogen atom is delocalized and contributes to the aromatic pi electron system. In these compounds, the nitrogen atom is connected to a hydrogen atom. Examples of non-basic nitrogen-containing aromatic rings are pyrroleFacts About Pyrrole Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N.... and indoleIndole Indole is an aromatic heterocyclic organic compound.... . 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 basic nitrogen-containing rings). Criteria for Aromaticity Molecule must be cyclic. Every atom in the ring must have a p orbital, which overlaps with p orbitals on either side (completely conjugatedConjugated system A chemically conjugated system is a system of atoms covalently bonded with alternating single and multiple bonds in a molecu... ). Molecule must be planar. It must contain an odd number of pairs of pi electrons; must satisfy Huckel's rule: (4n+2) pi electrons, where n is an integer starting at zero. In contrast, molecules with 4n pi electrons are antiaromatic. See also Polycyclic aromatic compounds Polycyclic aromatic hydrocarbons (PAH)