Naphthalene details as wikipedia:

As a chemical intermediate

Naphthalene is used mainly as a precursor to other chemicals. The single largest use of naphthalene is the industrial production of phthalic anhydride, although more phthalic anhydride is made from o-xylene. Other naphthalene-derived chemicals include alkyl naphthalene sulfonate surfactants, and the insecticide 1-naphthyl-N-methylcarbamate (carbaryl). Naphthalenes substituted with combinations of strongly electron-donating functional groups, such as alcohols and amines, and strongly electron-withdrawing groups, especially sulfonic acids, are intermediates in the preparation of many synthetic dyes. The hydrogenated naphthalenes tetrahydronaphthalene (tetralin) and decahydronaphthalene (decalin) are used as low-volatility solvents. Naphthalene is also used in the synthesis of 2-naphthol, a precursor for various dyestuffs, pigments, rubber processing chemicals and other miscellaneous chemicals and pharmaceuticals.^[4]

Naphthalene sulfonic acids are used in the manufacture of naphthalene sulfonate polymer plasticizers (dispersants), which are used to produce concrete and plasterboard(wallboard or drywall). They are also used as dispersants in synthetic and natural rubbers, and as tanning agents (syntans) in leather industries, agricultural formulations (dispersants for pesticides), dyes and as a dispersant in lead–acid battery plates.

Naphthalene sulfonate polymers are produced by reacting naphthalene with sulfuric acid and then polymerizing with formaldehyde, followed by neutralization with sodium hydroxide or calcium hydroxide. These products are commercially sold in solution (water) or dry powder form.

• Sulfonation Step (sulfuric acid plus naphthalene):

H₂SO₄ + C₁₀H₈ → C₁₀H₇-SO₃H + H₂O

• Polymerization Step (naphthalenesulfonic acid plus formaldehyde):

C₁₀H₇-SO₃H + CH₂-O → C₁₀H₇-SO₃H-(C₁₀H₇-SO₃H)_n + H₂SO₄

• Neutralization Step (naphthalene sulfonic acid condensate plus sodium hydroxide):

C₁₀H₇-SO₃H-(C₁₀H₇-SO₃H)_n + NaOH → C₁₀H₇-SO₃Na-(C₁₀H₇-SO₃Na)_n + H₂O + Na₂SO₄

[edit]Wetting agent and surfactant

Alkyl naphthalene sulfonates (ANS) are used in many industrial applications as nondetergent 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, and the textile and fabric industry, which utilizes the wetting and defoaming properties of ANS for bleaching and dyeing operations.

[edit]As a fumigant

The most familiar use of naphthalene is as a household fumigant, such as in mothballs although 1,4-dichlorobenzene (or p-dichlorobenzene) is now more widely used. In a sealed container containing naphthalene pellets, naphthalene vapors build up to levels toxic to both the adult and larval forms of many moths that attack textiles. Other fumigant uses of naphthalene include use in soil as a fumigant pesticide, in attic spaces to repel animals and insects, and in museum storage-drawers and cupboards to protect the contents from attack by insect pests.

[edit]Niche applications

It 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. Naphthalene is used in engineering to study heat transfer using mass sublimation.