Polynuclear Aromatic Hydrocarbons
Polynuclear Aromatic Hydrocarbons are such hydrocarbons having more than one aromatic nucleus.
Polynuclear Aromatic Hydrocarbons are of two types. The first type of PNHs contains more than two benzene ring which are either isolated from each other i.e. attached at one point and thus benzene rings are independent. Examples- Biphenyl, Diphenylmethane, Triphenylmethane etc.
The second type of PNHs contains two or more benzene rings which are fused with each other at two common points. Examples- Naphthalene, Anthracene, Phenanthrene etc.