# Nomenclature of Aromatic Compounds

## Systematic Nomenclature of Aromatic Compounds

Analogous to alkanes, alkenes, and alkynes, alkyl-substituted benzenes are also called arenes. The aromatic $C6H5$- residue is called phenyl. The name depends on the length of the alkyl substituent. If the substituent contains no more than six carbon atoms, the compound's parent name is benzene. This would then be classified as an alkylbenzene, such as is the case with ethylbenzene and 2-pentylbenzene. However, if the alkyl substituent possesses more than six carbon atoms, the compound is considered to be a phenylalkane (or -alkene, or -alkyne, respectively), such is the case with 3-phenyloctane. Above all in empirical and structural formulas, the phenyl group is often abbreviated by "Ph". The name phenyl derives from the Greek word "phainein" (= shine), as Michael Faraday first discovered phenol in the liquid residue that condensed from the gas phase in London's street lamps when whale oil was burnt. The $C6H5CH2$- residue is called benzyl.

Fig.1
Parent names of aromatic compounds.

The different dihydroxybenzenes display different chemical properties.

Fig.2

Catechol (o-dihydroxybenzene)

Fig.3

Resorcinol (m-dihydroxybenzene)

Fig.4

Hydroquinone (p-dihydroxybenzene)

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