Naphthalene is an the simplest polycyclic aromatic hydrocarbon organic compound with formula C10H8 and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene’s structure consist of a fused pair of benzene rings. Naphthalene is best known as the main ingredient of traditional mothballs.
From the distillation of coal tar, an oil of 50% naphthalene mixed with other aromatic compounds is obtained. This oil is then washed with aqueous caustic soda to to remove acidic compounds such as phenols before adding sulfuric acid to remove basic compounds. The oil then undergoes fractional distillation to obtain crude naphthalene of 95% naphthalene by weight.
Naphthalene is used mainly as a precursor to other chemicals. The single largest use of naphthalene is the industrial production of phthalic anhydride. Naphthalene is also used as a synthesis in various dyestuffs, pigments, rubber processing chemicals, other miscellaneous chemicals and pharmaceuticals.
Naphthalene sulfonic acids, which is made from naphthalene, are used in the manufacturing of naphthalene sulfonate polymer plasticizers (dispersants), which are used to produce concrete and plasterboard (wallboard or drywall). They are also used in dispersants in synthetic and natural rubbers, and as tanning agents (syntans) in leather industries, dyeing and as a dispersant in lead-acid battery plates.
Alkyl naphthalene sulfonates (ANS) are used in many industrial applications as non-detergent wetting agents that effectively disperse colloidal systems in aqueous media. The major commercial applications are in the agricultural chemical industry, which uses ANS for wettable powder and wettable granular (dry-flowable) formulations. Naphthalene is also used as a pesticide.
Naphthalene is used in pyrotechnic special effects such as the generation of black smoke and simulated explosions. In the past, naphthalene was administered orally to kill parasitic worms in livestock. Naphthalene and its alkyl homologs are the major constituents of creosote. Napthalene is also used to repel animals and insects and in museum storage-drawers and cupboards to protect the contents from attack by insect pests.