Polynuclear hydrocarbons are aromatic compounds containing two or more fused benzene rings. They exhibit aromatic character and unique chemical reactivity.
Naphthalene consists of two fused benzene rings. It undergoes electrophilic substitution reactions mainly at the alpha position.
Anthracene contains three fused benzene rings in a linear arrangement. It is reactive at the 9 and 10 positions.
Phenanthrene consists of three fused benzene rings arranged angularly. It is more stable compared to anthracene.
Many biologically active compounds and drugs contain fused aromatic systems. Understanding polynuclear hydrocarbons helps in medicinal chemistry and drug design.