Naphthalene

PROPERTIES

Naphthalene is a crystalline, white, solid. Insoluble in water, slightly soluble in methanol, ethanol, soluble in organic solvents and very soluble in ether, chloroform, or carbon disulfide. Flammable. Hygroscopic. Evaporates easily producing a characteristic odor. Reacts strongly with strong oxidants and non-violently with strong acids.

APPLICATIONS

FUMIGANTS (MOTHBALLS – household fumigants)

Naphthalene is known as the traditional, primary ingredient of mothballs. It kills moths and moth larvae with the vapor.

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. Such uses are now limited.

CHEMICAL INTERMEDIATES

Naphthalene is mainly used as a precursor to other chemicals. Some naphthalene-derived chemicals are lisetd below:

WETTING AGENTS/SURFACTANTS

Alkyl naphthalene sulfonates (ANS) are used as nondetergent wetting agents that effectively disperse colloidal systems in aqueous media which are used in paints and coatings and in a variety of pesticides and cleaner formulations. Textile and fabric industry utilize the wetting and defoaming properties of ANS for bleaching and dyeing operations.

PLASTICIZERS

Naphthalene sulfonate polymer plasticizers are used to produce concrete and plasterboard (wallboard or drywall), also as dispersants in synthetic and natural rubbers, and as tanning agents in leather industries, in agricultural formulations (dispersants for pesticides), dyes and as dispersants in lead-acid battery plates.

INSECTICIDES

1-naphthyl-N-methylcarbamate (carbaryl) is used as a general-purpose, broad-spectrum insecticide.

DYES

Naphthalenes substituted with combinations of strongly electron-donating functional groups, such as alcohols and amines, and strongly electron-witherawing groups, especially sulfonic acids are used as dyes.

LUBRICANTS AND MOTOR FUELS (LOW-VOLATILITY SOLVENTS)

The hydrogenated naphthalenes tetrahydronaphthalene (tetralin) and decahydronaphthalene (decalin) are solvents in lubricants and in motor fuels.

2-naphthol

That is a precursor for various dyestuffs, pigments, rubber processing chemicals and other miscellaneous chemicals and pharmaceuticals.

Other uses include:

Pyrotechnic special effects such as the generation of black smoke and simulated explosions.

Engineering, to study heat transfer using mass sublimation.

Production of phthalic anhydride (used in the production of dyes, polyvinyl chloride plasticizers, insecticides, some pharmaceutical products),  polyethylene naphthalene (for making plastic beer bottles).

Creating artificial pores in the manufacture of high-porosity grinding wheels.

Paint and fuel additive products (e.g. HITEC 4110 for diesel fuels).

Component of coal tar creosote (it was used as a wood preservative, however, in the EU its use has since been banned for amateur and unlicensed professional applications due to the health effects of many other toxic constituent compounds)

Notes:

Naphthalene has been classified by the International Agency for Research on Cancer as being possibly carcinogenic in humans.