Naphthalene
Overview
 
Naphthalene is an organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 . It 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
Aromaticity
In organic chemistry, Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. The earliest use of the term was in an article by August...

 hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

, naphthalene's structure consists of a fused pair of benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

 rings. It is best known as the main ingredient of traditional mothball
Mothball
Mothballs are small balls of chemical pesticide and deodorant used when storing clothing and other articles susceptible to damage from mold or moth larvae ....

s.
In 1819–1820, at least two chemists reported a white solid with a pungent odor derived from the distillation of coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

.
Encyclopedia
Naphthalene is an organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 . It 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
Aromaticity
In organic chemistry, Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. The earliest use of the term was in an article by August...

 hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

, naphthalene's structure consists of a fused pair of benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

 rings. It is best known as the main ingredient of traditional mothball
Mothball
Mothballs are small balls of chemical pesticide and deodorant used when storing clothing and other articles susceptible to damage from mold or moth larvae ....

s.

History

In 1819–1820, at least two chemists reported a white solid with a pungent odor derived from the distillation of coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

. In 1821, John Kidd described many of this substance's properties and the means of its production, and proposed the name naphthaline, as it had been derived from a kind of naphtha
Naphtha
Naphtha normally refers to a number of different flammable liquid mixtures of hydrocarbons, i.e., a component of natural gas condensate or a distillation product from petroleum, coal tar or peat boiling in a certain range and containing certain hydrocarbons. It is a broad term covering among the...

 (a broad term encompassing any volatile, flammable liquid hydrocarbon mixture, including coal tar). Naphthaline's chemical formula was determined by Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....

 in 1826. The structure of two fused benzene rings was proposed by Emil Erlenmeyer in 1866, and confirmed by Carl Gräbe
Carl Gräbe
Carl Gräbe was a German chemist from Frankfurt am Main.Gräbe studied at a vocational high school in Frankfurt and Karlsruhe Polytechnic and in Heidelberg. Later he worked for the chemical company Meister Lucius und Brüning . He supervised the production of Fuchsine and researched violet colorants...

 three years later.

Structure and reactivity

A naphthalene molecule can be viewed as the fusion of a pair of benzene rings. (In organic chemistry
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...

, rings are fused if they share two or more atoms.) As such, naphthalene is classified as a benozenoid polycyclic aromatic hydrocarbon
Polycyclic aromatic hydrocarbon
Polycyclic aromatic hydrocarbons , also known as poly-aromatic hydrocarbons or polynuclear aromatic hydrocarbons, are potent atmospheric pollutants that consist of fused aromatic rings and do not contain heteroatoms or carry substituents. Naphthalene is the simplest example of a PAH...

 (PAH). There are two sets of equivalent hydrogen atoms: the alpha positions are positions 1, 4, 5, and 8 on the drawing below, and the beta positions are positions 2, 3, 6, and 7.

Unlike benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

, the carbon-carbon bonds in naphthalene are not of the same length. The bonds C1–C2, C3–C4, C5–C6 and C7–C8 are about 1.36 Å (136 pm) in length, whereas the other carbon-carbon bonds are about 1.42 Å (142 pm) long. This difference, which was established by x-ray diffraction, is consistent with the valence bond
Valence bond theory
In chemistry, valence bond theory is one of two basic theories, along with molecular orbital theory, that were developed to use the methods of quantum mechanics to explain chemical bonding. It focuses on how the atomic orbitals of the dissociated atoms combine to give individual chemical bonds...

 model of bonding in naphthalene that involves three resonance structures (as shown below); whereas the bonds C1–C2, C3–C4, C5–C6 and C7–C8 are double in two of the three structures, the others are double in only one.



Like benzene, naphthalene can undergo electrophilic aromatic substitution
Electrophilic aromatic substitution
Electrophilic aromatic substitution EAS is an organic reaction in which an atom, usually hydrogen, appended to an aromatic system is replaced by an electrophile...

. For many electrophilic aromatic substitution reactions, naphthalene reacts under milder conditions than does benzene. For example, whereas both benzene and naphthalene react with chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 in the presence of a ferric chloride or aluminium chloride
Aluminium chloride
Aluminium chloride is the main compound of aluminium and chlorine. It is white, but samples are often contaminated with iron trichloride, giving it a yellow colour. The solid has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large...

 catalyst, naphthalene and chlorine can react to form 1-chloronaphthalene
1-Chloronaphthalene
1-Chloronaphthalene is an aromatic compound. It is a colorless, oily liquid which may be used to determine the refractive index of crystals by immersion....

 even without a catalyst. Likewise, whereas both benzene and naphthalene can be alkylated using Friedel-Crafts reaction
Friedel-Crafts reaction
The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877. There are two main types of Friedel–Crafts reactions: alkylation reactions and acylation reactions. This reaction type is a form of electrophilic aromatic substitution...

s, naphthalene can also be alkylated by reaction with alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s or alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

s, with sulfuric
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 or phosphoric acid
Phosphoric acid
Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...

 as the catalyst.

Substituted derivatives

Two isomer
Isomer
In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

s are possible for mono-substituted naphthalenes, corresponding to substitution at an alpha or beta position. Usually, electrophiles attack at the alpha position. The selectivity for alpha over beta substitution can be rationalized in terms of the resonance structures of the intermediate: for the alpha substitution intermediate, seven resonance structures can be drawn, of which four preserve an aromatic ring. For beta substitution, the intermediate has only six resonance structures, and only two of these are aromatic. Sulfonation, however, gives a mixture of the "alpha" product 1-naphthalenesulfonic acid and the "beta" product 2-naphthalenesulfonic acid, with the ratio dependent on reaction conditions. The 1-isomer forms predominantly at 25 °C, and the 2-isomer at 160 °C.

Naphthalene can be hydrogenated under high pressure in the presence metal catalysts to give 1,2,3,4-tetrahydronaphthalene or tetralin
Tetralin
Tetralin is a hydrocarbon having the chemical formula C10H12. This molecule is similar to the naphthalene chemical structure except that one ring is saturated.The compound can be synthesized in a Bergman cyclization...

 . Further hydrogenation yields decahydronaphthalene or decalin . Oxidation with chromate
Chromate
Chromate salts contain the chromate anion, CrO42−. Dichromate salts contain the dichromate anion, Cr2O72−. They are oxyanions of chromium in the oxidation state +6. They are moderately strong oxidizing agents.- Chemical properties :...

 or permanganate
Permanganate
A permanganate is the general name for a chemical compound containing the manganate ion, . Because manganese is in the +7 oxidation state, the permanganate ion is a strong oxidizing agent. The ion has tetrahedral geometry...

, or catalytic oxidation with and a vanadium
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...

 catalyst, gives phthalic acid
Phthalic acid
Phthalic acid is an aromatic dicarboxylic acid, with formula C6H42. It is an isomer of isophthalic acid and terephthalic acid. Although phthalic acid is of modest commercial importance, the closely related derivative phthalic anhydride is a commodity chemical produced on a large...

.

Production

Most naphthalene is derived from coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

. From the 1960s until the 1990s, significant amounts of naphthalene were also produced from heavy petroleum fractions during petroleum refining, but today petroleum-derived naphthalene represents only a minor component of naphthalene production.

Naphthalene is the most abundant single component of coal tar. Although the composition of coal tar varies with the coal from which it is produced, typical coal tar is about 10% naphthalene by weight. In industrial practice, distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

 of coal tar yields an oil containing about 50% naphthalene, along with a variety of other aromatic compounds. This oil, after being washed with aqueous sodium hydroxide to remove acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ic components (chiefly various phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

s), and with sulfuric acid to remove basic
Base (chemistry)
For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...

 components, undergoes fractional distillation
Fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation...

 to isolate naphthalene. The crude naphthalene resulting from this process is about 95% naphthalene by weight, often referred to as 78°C (melting point). The chief impurities are the sulfur-containing aromatic compound benzothiophene
Benzothiophene
Benzothiophene is an aromatic organic compound with a molecular formula C8H6S and an odor similar to naphthalene . It occurs naturally as a constituent of petroleum-related deposits such as lignite tar. Benzothiophene has no household use...

 (<2%), indane
Indane
Indane or indan is a hydrocarbon petrochemical compound.-Derivatives:Derivatives include compounds such as 1-methyl-indane and 2-methyl-indane , 4-methyl-indane and 5-methyl-indane , various dimethyl-indanes, and various pharmaceutical derivatives...

 (0.2%), indene
Indene
Indene is a flammable polycyclic hydrocarbon with chemical formula C9H8. It is composed of a benzene ring fused with a cyclopentene ring. This aromatic liquid is colorless although samples often are pale yellow...

 (<2%), and methylnapthalene (<2%). Petroleum-derived naphthalene is usually purer than that derived from coal tar. Where required, crude naphthalene can be further purified by recrystallization
Recrystallization (chemistry)
-Chemistry:In chemistry, recrystallization is a procedure for purifying compounds. The most typical situation is that a desired "compound A" is contaminated by a small amount of "impurity B". There are various methods of purification that may be attempted , which includes recrystallization...

 from any of a variety of solvents, resulting in 99% naphthalene by weight, referred to as 80 °C (melting point). Approximately 1M tons are produced annually.

In North America, coal tar producers are Koppers
Koppers
Koppers is a global chemical and materials company based in Downtown Pittsburgh, Pennsylvania, United States in an art-deco 1920s skyscraper, the Koppers Tower.-Structure:...

 Inc. and Recochem Inc., and petroleum-derived producer is Advanced Aromatics, L.P.

Natural occurrence

Trace amounts of naphthalene are produced by magnolia
Magnolia
Magnolia is a large genus of about 210 flowering plant species in the subfamily Magnolioideae of the family Magnoliaceae. It is named after French botanist Pierre Magnol....

s and specific types of deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...

, as well as the Formosan subterranean termite
Formosan subterranean termite
The Formosan subterranean termite is an invasive species of termite. It has been transported worldwide from its native range in southern China to Formosa and Japan...

, possibly produced by the termite as a repellant against "ants, poisonous fungi and nematode worms." Some strains of the endophytic fungus Muscodor albus
Muscodor albus
Muscodor albus is a plant-dwelling fungus in the Xylariaceae family. It was first discovered in the bark of a cinnamon tree in Honduras. It has the ability to produce a mixture of volatile compounds, including alcohols and esters, which can kill pathogens like molds and bacteria such as listeria...

produce naphthalene among a range of volatile organic compounds, while Muscodor vitigenus
Muscodor vitigenus
Muscodor vitigenus is an endophytic fungus which colonizes Paullinia paullinioides, a liana of the Peruvian Amazon rainforests. It has the unusual property of, under certain circumstances, producing near-pure naphthalene, an insect repellent.-References:*...

produces naphthalene almost exclusively.

Naphthalene has been found in meteorites. It has also been discovered in the interstellar medium in the direction of the star Cernis 52 in the constellation Perseus
Perseus (constellation)
Perseus is a constellation in the northern sky, named after the Greek hero Perseus. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations defined by the International Astronomical Union...

.

Gaseous naphthalene

Recent research at the University of Georgia, led by Dr. Michael Duncan, has shown that protonated cations of naphthalene are the source of part of the spectrum of the Unidentified Interstellar Bands (UIBs). The gaseous naphthalene found in space is different from crystalline form typically used in mothballs in that it has an additional hydrogen atom, with the empirical formula: . The UIBs have been observed by astronomers, and until recently, there has been no solid evidence identifying the compounds responsible for them. The research has recently been publicized as "Mothballs in Space."

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
Phthalic anhydride
Phthalic anhydride is the organic compound with the formula C6H42O. It is the anhydride of phthalic acid. This colourless solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics. In 2002, approximately 4.6 billion kilograms were...

, although more phthalic anhydride is made from o-xylene
O-Xylene
o-Xylene is an aromatic hydrocarbon, based on benzene with two methyl substituents bonded to adjacent carbon atoms in the aromatic ring .It is a constitutional isomer of m-xylene and p-xylene....

. Other naphthalene-derived chemicals include alkyl naphthalene sulfonate surfactant
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...

s, and the insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...

 1-naphthyl-N-methylcarbamate (carbaryl)
Carbaryl
Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid commonly sold under the brand name Sevin, a trademark of the Bayer Company. Union Carbide discovered carbaryl and introduced it commercially in 1958...

. Naphthalenes substituted with combinations of strongly electron-donating functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

s, such as alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

s and amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

s, and strongly electron-withdrawing groups, especially sulfonic acid
Sulfonic acid
Sulfonic acid usually refers to a member of the class of organosulfur compounds with the general formula RS2–OH, where R is an alkyl or aryl. The formal part of acid, HS2–OH, are formally derivatives of the "parent" inorganic compound with the formula HSO2.-Preparation:Sulfonic acid is...

s, are intermediates in the preparation of many synthetic dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

s. The hydrogenated naphthalenes tetrahydronaphthalene (tetralin
Tetralin
Tetralin is a hydrocarbon having the chemical formula C10H12. This molecule is similar to the naphthalene chemical structure except that one ring is saturated.The compound can be synthesized in a Bergman cyclization...

) and decahydronaphthalene (decalin) are used as low-volatility solvents. Naphthalene is also used in the synthesis of 2-naphthol
2-Naphthol
2-Naphthol, or β-naphthol, is a colorless crystalline solid with the formula C10H7OH. It is an isomer of 1-naphthol, differing by the location of the hydroxyl group on naphthalene. The naphthols are naphthalene homologues of phenol, with the hydroxyl group being more reactive than in the phenols....

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

Naphthalene sulfonic acids are used in the manufacture of naphthalene sulfonate polymer plasticizers (dispersants), which are used to produce concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 and plasterboard (wallboard or drywall
Drywall
Drywall, also known as plasterboard, wallboard or gypsum board is a panel made of gypsum plaster pressed between two thick sheets of paper...

). They are also used as dispersants in synthetic and natural rubbers, and as tanning
Tanning
Tanning is the making of leather from the skins of animals which does not easily decompose. Traditionally, tanning used tannin, an acidic chemical compound from which the tanning process draws its name . Coloring may occur during 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
Formaldehyde
Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

, followed by neutralization with sodium hydroxide or calcium hydroxide
Calcium hydroxide
Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca2. It is a colourless crystal or white powder and is obtained when calcium oxide is mixed, or "slaked" with water. It has many names including hydrated lime, builders lime, slack lime, cal, or...

. These products are commercially sold in solution (water) or dry powder form.
  • Sulfonation Step (sulfuric acid plus naphthalene):

+ → +
  • Polymerization
    Polymerization
    In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...

     Step (naphthalenesulfonic acid plus formaldehyde):

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

+ NaOH → + +

Wetting agent/surfactant

Alkyl naphthalene sulfonates (ANS) are used in many industrial applications as nondetergent wetting agents
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...

 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.

As a fumigant

The most familiar use of naphthalene is as a household fumigant, such as in mothball
Mothball
Mothballs are small balls of chemical pesticide and deodorant used when storing clothing and other articles susceptible to damage from mold or moth larvae ....

s although 1,4-dichlorobenzene
1,4-Dichlorobenzene
1,4-Dichlorobenzene is an organic compound with the formula C6H4Cl2. This colorless solid has a strong odor. It consists of two chlorine atoms substituted at opposing sites on a benzene ring. p-DCB is used a pesticide and a deodorant, most familiarly in mothballs in which it is a replacement for...

 (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 moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

s that attack textiles. Other fumigant uses of naphthalene include use in soil as a fumigant pesticide, in attic
Attic
An attic is a space found directly below the pitched roof of a house or other building . Attic is generally the American/Canadian reference to it...

 spaces to repel animals and insects, and in museum storage-drawers and cupboards to protect the contents from attack by insect pests.

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
Creosote
Creosote is the portion of chemical products obtained by the distillation of a tar that remains heavier than water, notably useful for its anti-septic and preservative properties...

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

Health effects

Exposure to large amounts of naphthalene may damage or destroy red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...

s. Humans, in particular children, have developed this condition, known as hemolytic anemia
Hemolytic anemia
Hemolytic anemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells , either in the blood vessels or elsewhere in the human body . It has numerous possible causes, ranging from relatively harmless to life-threatening...

, after ingesting mothballs or deodorant blocks containing naphthalene. Symptoms include fatigue, lack of appetite, restlessness, and pale skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

. Exposure to large amounts of naphthalene may cause confusion
ConFusion
ConFusion is an annual science fiction convention organized by the Stilyagi Air Corps and its parent organization, the Ann Arbor Science Fiction Association. Commonly, it is held the third weekend of January. It is the oldest science fiction convention in Michigan, a regional, general SF con...

, nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

, vomiting, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

, blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 in the urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

, and jaundice
Jaundice
Jaundice is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae , and other mucous membranes caused by hyperbilirubinemia . This hyperbilirubinemia subsequently causes increased levels of bilirubin in the extracellular fluid...

 (yellow coloration of the skin).

When the U.S. National Toxicology Program exposed male and female rats and mice to naphthalene vapors on weekdays for two years, male and female rats exhibited evidence of carcinogenic activity based on increased incidences of adenoma and neuroblastoma of the nose, female mice exhibited some evidence of carcinogenic activity based on increased incidences of alveolar and bronchiolar adenomas of the lung, and male mice exhibited no evidence of carcinogenic activity.

The International Agency for Research on Cancer
International Agency for Research on Cancer
The International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organisation of the United Nations....

 (IARC) classifies naphthalene as possibly carcinogenic to humans and animals (Group 2B). The IARC also points out that acute exposure causes cataracts in humans, rats, rabbits, and mice; and that hemolytic anemia, described above, can occur in children and infants after oral or inhalation exposure or after maternal exposure during pregnancy. Under California's Proposition 65, naphthalene is listed as "known to the State to cause cancer".

Over 400 million people have an inherited condition called glucose-6-phosphate dehydrogenase deficiency
Glucose-6-phosphate dehydrogenase deficiency
Glucose-6-phosphate dehydrogenase deficiency is an X-linked recessive hereditary disease characterised by abnormally low levels of glucose-6-phosphate dehydrogenase , a metabolic enzyme involved in the pentose phosphate pathway, especially important in red blood cell metabolism. G6PD deficiency is...

. Exposure to naphthalene is more harmful for these people and may cause hemolytic anemia
Hemolytic anemia
Hemolytic anemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells , either in the blood vessels or elsewhere in the human body . It has numerous possible causes, ranging from relatively harmless to life-threatening...

 at lower doses.

In China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, the use of naphthalene in mothballs is forbidden. It is due partly to the health effects as well as the wide use of natural camphor
Camphor
Camphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula C10H16O. It is found in wood of the camphor laurel , a large evergreen tree found in Asia and also of Dryobalanops aromatica, a giant of the Bornean forests...

 as replacement.

See also

  • Decalin
  • Camphor
    Camphor
    Camphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula C10H16O. It is found in wood of the camphor laurel , a large evergreen tree found in Asia and also of Dryobalanops aromatica, a giant of the Bornean forests...

  • Naphthol
  • Classic naphthalene synthesis: the Wagner-Jauregg reaction
    Wagner-Jauregg reaction
    The Wagner-Jauregg reaction is a classic organic reaction in organic chemistry, named after Theodor Wagner-Jauregg, describing the double Diels–Alder reaction of 2 equivalents of maleic anhydride with a 1,1-diarylethylene...

  • Sodium naphthalenide
    Sodium naphthalenide
    Sodium naphthalenide, also known as sodium naphthalide, is a soluble one-electron reductant employed in organic, organometallic, and inorganic chemistry. It is prepared by stirring sodium metal with naphthalene in a polar solvent such as tetrahydrofuran or dimethoxyethane, resulting in the...


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