Naphthalene, the simplest of the fused or condensed ring hydrocarbon compounds composed of two benzene rings sharing two adjacent carbon atoms chemical formula, C8 H10 .It is commercially produced by crystallization from the intermediate fraction of condensed coal tar and from the heavier fraction of cracked petroleum.Naphthalene is the most abundant single constituent of coal tar, a volatile product from the destructive distillation of coal, and is also formed in modern processes for the high temperature cracking (breaking up of large molecules) of petroleum.Its reactions are mainly reactions of substitution of hydrogen atoms by halogen atoms, nitro groups, sulfonic acid groups, and alkyl groups.Large quantities of naphthalene are converted to naphthylamines and naphthols for use as dyestuff intermediates.C .