Aromatic rings benzene

Aromatic hydrocarbon a hydrocarbon characterized by the presence of an aromatic ring or condensed aromatic rings benzene and substituted benzene, naphthalene and substituted naphthalene, phenan-threne and substituted phenan-threne, as well as the higher condensed ring systems compounds that are distinct from those of aliphatic compounds (q.v.) or ali-cyclic compounds (q.v.). 

Cyclopropanation of monocyclic aromatic rings (benzene and its derivatives) yields 7-acyl-bicyclo[4.1.0]hepta-2,5-dienes that are subject to the norcaradiene/cycloheptatriene valence equilibrium (see Houben-Weyl, Vol.4/3, p509 and Section 1.2.I.2.4.2.6.2.). Whereas 7-mono-... 

Platinum metallopolyynes containing Z -C Porphyrin chromophores and electron-rich aromatic rings (benzene and/or... 

Because of the stability of the aromatic ring, benzene is more stable than a straight-chain alkene, and it undergoes substitution rather than addition reactions. 

A summary of the more important aromatic ring (benzene) group frequencies is given in Table 5.4. 

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