Naphthalene is an
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...
with formula . It is the simplest
polycyclic aromatic hydrocarbon, and is a white
crystalline solid
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...
with a characteristic odor that is detectable at concentrations as low as 0.08
ppm by mass. As an
aromatic
In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...
hydrocarbon, naphthalene's structure consists of a fused pair of
benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...
rings. It is best known as the main ingredient of traditional
mothballs.
History
In the early 1820s, two separate reports described a white solid with a pungent odor derived from the
distillation
Distillation, or classical distillation, is the process of separation process, separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distilla ...
of
coal tar
Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote. It has both medical and industrial uses. Medicinally it is a topical medication applied to skin to treat psoriasi ...
. In 1821,
John Kidd cited these two disclosures and then described many of this substance's properties and the means of its production. He proposed the name ''naphthaline'', as it had been derived from a kind of
naphtha
Naphtha ( or ) is a flammable liquid hydrocarbon mixture.
Mixtures labelled ''naphtha'' have been produced from natural gas condensates, petroleum distillates, and the distillation of coal tar and peat. In different industries and regions ''n ...
(a broad term encompassing any volatile, flammable liquid hydrocarbon mixture, including coal tar). Naphthalene's chemical formula was determined by
Michael Faraday
Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic inducti ...
in 1826. The structure of two fused
benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...
rings was proposed by
Emil Erlenmeyer in 1866, and confirmed by
Carl Gräbe
Carl Gräbe (; 24 February 1841 – 19 January 1927) was a German industrial and academic chemist from Frankfurt am Main who held professorships in his field at Leipzig, Königsberg, and Geneva. He is known for the first synthesis of the ec ...
three years later.
Physical properties
A naphthalene molecule can be viewed as the fusion of a pair of
benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...
rings. (In
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...
, rings are ''fused'' if they share two or more atoms.) As such, naphthalene is classified as a benzenoid
polycyclic aromatic hydrocarbon (PAH).
The eight carbon atoms that are not shared by the two rings carry one hydrogen atom each. For purpose of the standard
IUPAC
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
nomenclature of derived compounds, those eight atoms are numbered 1 through 8 in sequence around the perimeter of the molecule, starting with a carbon atom adjacent to a shared one. The shared carbon atoms are labeled 4a (between 4 and 5) and 8a (between 8 and 1).
Molecular geometry
The molecule is planar, like benzene. Unlike benzene, 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 1.37 Å (137 pm) in length, whereas the other carbon–carbon bonds are about 1.42 Å (142 pm) long. This difference, established by
X-ray diffraction
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...
, is consistent with the
valence bond model in naphthalene and in particular, with the theorem of
cross-conjugation
Cross-conjugation is a special type of conjugation in a molecule, when in a set of three pi bonds only two pi bonds interact with each other by conjugation, while the third one is excluded from interaction. Whereas a normal conjugated system such a ...
. This theorem would describe naphthalene as an
aromatic
In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...
benzene unit bonded to a
diene
In organic chemistry a diene ( ) (diolefin ( ) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alk''ene'' units, with the standard prefix ''di'' of systematic nomenclature. ...
but not extensively
conjugated to it (at least in the
ground state
The ground state of a quantum-mechanical system is its stationary state of lowest energy; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the ground state. ...
), which is consistent with two of its three
resonance
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...
structures.
:
Because of this resonance, the molecule has
bilateral symmetry
Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...
across the plane of the shared carbon pair, as well as across the plane that bisects bonds C2-C3 and C6-C7, and across the plane of the carbon atoms. Thus there are two sets of equivalent hydrogen atoms: the ''alpha'' positions, numbered 1, 4, 5, and 8, and the ''beta'' positions, 2, 3, 6, and 7. Two
isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
Iso ...
s are then possible for mono-substituted naphthalenes, corresponding to substitution at an alpha or beta position.
Structural isomer
In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a chemical compound, compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct chemical bond, b ...
s of naphthalene that have two fused aromatic rings include
azulene, which has a 5–7 fused ring system, and
Bicyclo ecapentaene">.2.0ecapentaene which has a fused 4–8 ring system.
The point group symmetry of naphthalene is ''D
2h''.
Electrical conductivity
Pure crystalline naphthalene is a moderate insulator at room temperature, with
resistivity of about 10
12 Ω m. The resistivity drops more than a thousandfold on melting, to about 4 × 10
8 Ω m. Both in the liquid and in the solid, the resistivity depends on temperature as ''ρ'' = ''ρ''
0 exp(''E''/(''k'' ''T'')), where ''ρ''
0 (Ω m) and ''E'' (eV) are constant parameters, ''k'' is Boltzmann's constant (8.617×10
−5 eV/
K), and ''T'' is absolute temperature (K). The parameter ''E'' is 0.73 in the solid. However, the solid shows semiconducting character below 100 K.
Chemical properties
Reactions with electrophiles
In
electrophilic
In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carri ...
aromatic
substitution reactions, naphthalene reacts more readily than benzene. For example, chlorination and bromination of naphthalene proceeds without a
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
to give
1-chloronaphthalene and
1-bromonaphthalene
1-Bromonaphthalene is an organic compound with the formula C10H7Br. It is one of two isomeric bromonaphthalenes, the other being 2-bromonaphthalene. Under normal conditions, the substance is a colorless liquid.
Synthesis and reactions
It is pre ...
, respectively. Likewise, whereas both benzene and naphthalene can be
alkylated
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting al ...
using
Friedel–Crafts reaction
The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an aromatic ring. Friedel–Crafts reactions are of two main types: alkylation reactions and acylation reactions ...
s, naphthalene can also be easily alkylated by reaction with
alkene
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...
s or
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
s, using
sulfuric
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
or
phosphoric acid catalysts.
In terms of
regiochemistry
In chemistry, regioselectivity is the preference of chemical bonding or breaking in one direction over all other possible directions. It can often apply to which of many possible positions a reagent will affect, such as which proton a strong base ...
, 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 gives the "alpha" product
naphthalene-1-sulfonic acid as the kinetic product but
naphthalene-2-sulfonic acid
Naphthalene-2-sulfonic acid is an organic compound with the formula C10H7SO3H. A colorless, water-soluble solid, it is often available as the mono- and trihydrates C10H7SO3H.2H2O. It is one of two monosulfonic acids of naphthalene, the other be ...
as the thermodynamic product. The 1-isomer forms predominantly at 25 °C, and the 2-isomer at 160 °C.
Sulfonation to give the 1- and 2-sulfonic acid occurs readily:
: + → +
Further sulfonation give di-, tri-, and tetrasulfonic acids.
Lithiation
Analogous to the synthesis of
phenyllithium
Phenyllithium or lithobenzene is an organometallic agent with the empirical formula C6H5Li. It is most commonly used as a metalating agent in organic syntheses and a substitute for Grignard reagents for introducing phenyl groups in organic synthes ...
is the conversion of 1-bromonaphthalene to 1-lithionaphthalene, by
lithium–halogen exchange:
:C
10H
7Br + BuLi → C
10H
7Li + BuBr
The resulting lithionaphthalene undergoes a second lithiation, in contrast to the behavior of phenyllithium. These 1,8-dilithio derivatives are precursors to a host of
peri-naphthalene In organic chemistry, peri-naphthalenes are particular derivatives of naphthalene with the formula C10H6-1,8-X2. Owing to the rigidity of the naphthalene skeleton, these substituents on the 1- and 8-positions are constrained to be relatively close ...
derivatives.
Reduction and oxidation
With alkali metals, naphthalene forms the dark blue-green radical anion salts such as
sodium naphthalene
Sodium naphthalene is an organic salt with the chemical formula Na+. In the research laboratory, it is used as a reductant in the synthesis of organic, organometallic, and inorganic chemistry. It is usually generated in situ. When isolated, it ...
, Na
+C
10H. The naphthalene anions are strong reducing agents.
Naphthalene can be
hydrogenate
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic ...
d under high pressure in the presence of metal
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
s to give 1,2,3,4-tetrahydronaphthalene(), also known as
tetralin. Further hydrogenation yields decahydronaphthalene or
decalin
Decalin (decahydronaphthalene, also known as bicyclo .4.0ecane and sometimes decaline), a bicyclic organic compound, is an industrial solvent. A colorless liquid with an aromatic odor, it is used as a solvent for many resins or fuel additives.
I ...
().
Oxidation with in the presence of
vanadium pentoxide as
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
gives
phthalic anhydride:
:C
10H
8 + 4.5 O
2 → C
6H
4(CO)
2O + 2 CO
2 + 2 H
2O
This reaction is the basis of the main use of naphthalene.
Oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
can also be effected using conventional stoichiometric
chromate or
permanganate
A permanganate () is a chemical compound containing the manganate(VII) ion, , the conjugate base of permanganic acid. Because the manganese atom is in the +7 oxidation state, the permanganate(VII) ion is a strong oxidizing agent. The ion is a tra ...
reagents.
Production
![Naphthalene](https://upload.wikimedia.org/wikipedia/commons/0/04/Naphthalene.jpg)
Most naphthalene is derived from
coal tar
Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote. It has both medical and industrial uses. Medicinally it is a topical medication applied to skin to treat psoriasi ...
. From the 1960s until the 1990s, significant amounts of naphthalene were also produced from heavy
petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
fractions during
petroleum refining, but present-day production is mainly from coal tar. Approximately 1.3M tons are produced annually.
Naphthalene is the most abundant single component of coal tar. The composition of coal tar varies with coal type and processing, but typical coal tar is about 10% naphthalene by weight. In industrial practice,
distillation
Distillation, or classical distillation, is the process of separation process, separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distilla ...
of coal tar yields an oil containing about 50% naphthalene, along with twelve other
aromatic compound
Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past grouping ...
s. This oil, after being washed with aqueous
sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and alkali ...
to remove
acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
ic components (chiefly various
phenol
Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...
s), and with sulfuric acid to remove
basic
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
components, undergoes
fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to ...
to isolate naphthalene. The crude naphthalene resulting from this process is about 95% naphthalene by weight. The chief impurities are the sulfur-containing aromatic compound
benzothiophene (< 2%),
indane
Indane or indan is an organic compound with the formula C6H4(CH2)3. It is a colorless liquid hydrocarbon. It is a petrochemical, a bicyclic compound. It occurs at the level of about 0.1% in coal tar. It is usually produced by hydrogenation of ...
(0.2%),
indene
Indene is a flammable polycyclic hydrocarbon with chemical formula . It is composed of a benzene ring fused with a cyclopentene ring. This aromatic liquid is colorless although samples often are pale yellow. The principal industrial use of in ...
(< 2%), and
methylnaphthalene Methylnaphthalene may refer to:
* 1-Methylnaphthalene
* 2-Methylnaphthalene
2-Methylnaphthalene is a polycyclic aromatic hydrocarbon (PAH).
On February 22, 2014, NASA announced a greatly upgraded database for detecting and monitoring PAHs, inclu ...
(< 2%). Petroleum-derived naphthalene is usually purer than that derived from coal tar. Where required, crude naphthalene can be further purified by
recrystallization from any of a variety of solvents, resulting in 99% naphthalene by weight, referred to as 80 °C (melting point).
[.]
In
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, the coal tar producers are
Koppers
Koppers is a global chemical and materials company based in Pittsburgh, Pennsylvania, United States in an art-deco 1920s skyscraper, the Koppers Tower.
Structure
Koppers is an integrated global producer of carbon compounds, chemicals, and trea ...
Inc., Ruetgers Canada Inc. and Recochem Inc., and the primary petroleum producer is Monument Chemical Inc. In Western Europe the well-known producers are Koppers, Ruetgers, and Deza. In
Eastern Europe
Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural, and socio-economic connotations. The vast majority of the region is covered by Russ ...
, naphthalene is produced by a variety of integrated
metallurgy
Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys.
Metallurgy encompasses both the sc ...
complexes (Severstal, Evraz, Mechel, MMK) in
Russia
Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
, dedicated naphthalene and phenol makers INKOR, Yenakievsky Metallurgy plant in
Ukraine
Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...
and ArcelorMittal Temirtau in
Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
.
Other sources and occurrences
Naphthalene and its alkyl
homologs are the major constituents of
creosote.
Trace amounts of naphthalene are produced by
magnolia
''Magnolia'' is a large genus of about 210 to 340The number of species in the genus ''Magnolia'' depends on the taxonomic view that one takes up. Recent molecular and morphological research shows that former genera ''Talauma'', ''Dugandiodendro ...
s and some species of
deer
Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
, as well as the
Formosan subterranean termite
The Formosan termite (''Coptotermes formosanus'') is a species of termite local to southern China and introduced to Taiwan (formerly known as Formosa, where it gets its name), Japan, South Africa, Sri Lanka, Hawaii, and the continental United Sta ...
, possibly produced by the termite as a repellant against "ants,
poisonous fungi and
nematode
The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
worms." Some strains of the
endophytic
An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; h ...
fungus ''
Muscodor albus
''Muscodor albus'' (frequently spelled "muscador albus") is a plant-dwelling fungus in the family Xylariaceae. It was first discovered in the bark of a cinnamon tree in Honduras. It has the ability to produce a mixture of volatile compounds, incl ...
'' produce naphthalene among a range of volatile organic compounds, while ''
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. ...
'' produces naphthalene almost exclusively.
Uses
Naphthalene is used mainly as a precursor to derivative chemicals. The single largest use of naphthalene is the industrial production of
phthalic anhydride, although more phthalic anhydride is made from
''o''-xylene.
Fumigant
Naphthalene has been used as a
fumigant
Fumigation is a method of pest control or the removal of harmful micro-organisms by completely filling an area with gaseous pesticides—or fumigants—to suffocate or poison the pests within. It is used to control pests in buildings ( ...
. It was once the primary ingredient in
mothballs, although its use has largely been replaced in favor of alternatives such as
1,4-dichlorobenzene
1,4-Dichlorobenzene (1,4-DCB, ''p''-DCB, or ''para''-dichlorobenzene, sometimes abbreviated as PDCB or para) is an organic compound with the formula C6H4Cl2. This colorless solid has a strong odor. The molecule consists of a benzene ring with two ...
. In a sealed container containing naphthalene pellets, naphthalene vapors build up to levels toxic to both the adult and larval forms of many
moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s that attack textiles. Other
fumigant
Fumigation is a method of pest control or the removal of harmful micro-organisms by completely filling an area with gaseous pesticides—or fumigants—to suffocate or poison the pests within. It is used to control pests in buildings ( ...
uses of naphthalene include use in soil as a fumigant
pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
, in
attic
An attic (sometimes referred to as a '' loft'') is a space found directly below the pitched roof of a house or other building; an attic may also be called a ''sky parlor'' or a garret. Because attics fill the space between the ceiling of the ...
spaces to repel
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s and animals such as
opossum
Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North ...
s, and in museum storage-drawers and cupboards to protect the contents from attack by insect pests.
Solvent
Molten naphthalene provides an excellent solubilizing medium for poorly soluble aromatic compounds. In many cases it is more efficient than other high-boiling solvents, such as
dichlorobenzene,
benzonitrile,
nitrobenzene
Nitrobenzene is an organic compound with the chemical formula C6H5 NO2. It is a water-insoluble pale yellow oil with an almond-like odor. It freezes to give greenish-yellow crystals. It is produced on a large scale from benzene as a precursor t ...
and
durene
Durene, or 1,2,4,5-tetramethylbenzene, is an organic compound with the formula C6H2(CH3)4. It is a colourless solid with a sweet odor. The compound is classified as an alkylbenzene. It is one of three isomers of tetramethylbenzene, the other t ...
. The reaction of
C60 with
anthracene
Anthracene is a solid polycyclic aromatic hydrocarbon (PAH) of formula C14H10, consisting of three fused benzene rings. It is a component of coal tar. Anthracene is used in the Economic production, production of the red dye alizarin and other dyes ...
is conveniently conducted in refluxing naphthalene to give the 1:1
Diels–Alder adduct. The aromatization of hydroporphyrins has been achieved using a solution of
DDQ in naphthalene.
Derivative uses
The single largest use of naphthalene is the production of
phthalic anhydride, which is an intermediate used to make
plasticizers for
polyvinyl chloride, and to make
alkyd resin polymers used in paints and varnishes.
Sulfonic acids and sulfonates
Many
naphthalenesulfonic acids and sulfonates are useful. Naphthalenesulfonic acids are used in the synthesis of
1-naphthol
1-Naphthol, or α-naphthol, is a fluorescent organic compound with the formula . It is a white solid. It is an isomer of 2-naphthol differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are naphthalene homologues ...
and
2-naphthol, precursors for various dyestuffs, pigments, rubber processing chemicals and other chemicals and pharmaceuticals.
[ They are also used as dispersants in synthetic and natural rubbers, in agricultural ]pesticides
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampric ...
, in dyes, and in lead–acid battery
The lead–acid battery is a type of rechargeable battery first invented in 1859 by French physicist Gaston Planté. It is the first type of rechargeable battery ever created. Compared to modern rechargeable batteries, lead–acid batteries have ...
plates. Naphthalenedisulfonic acids such as Armstrong's acid
Armstrong's acid (naphthalene-1,5-disulfonic acid) is a fluorescent organic compound with the formula C10H6(SO3H)2. It is one of several isomers of naphthalenedisulfonic acid. It a colorless solid, typically obtained as the tetrahydrate. Like o ...
are used as precursors and to form pharmaceutical salts such as CFT CFT may refer to:
Chemistry
*(-)-2β-Carbomethoxy-3β-(4-fluorophenyl)tropane
* Cefatrizine, a cephalosporin antibiotic
*Crystal field theory, describes the breaking of degeneracies of electron orbital states
Mathematics and physics
* Class field ...
.
The aminonaphthalenesulfonic acids Aminonaphthalenesulfonic acids are compounds with the composition C10H6(NH2)(SO3H), being derived from naphthalene (C10H8) substituted by an amino and sulfonic acid groups. These compounds are colorless solids. They are useful precursors to dyes.G ...
are precursors for synthesis of many synthetic dye
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...
s.
Alkyl naphthalene sulfonates (ANS) are used in many industrial applications as nondetergent surfactant
Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming ...
s (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 in the textile and fabric industry, which uses the wetting and defoaming properties of ANS for bleaching and dyeing operations.
Some naphthalenesulfonate polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
s are superplasticizers used for the production of high strength concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
. They are produced by treating naphthalenesulfonic acid with formaldehyde
Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...
, followed by neutralization with sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and alkali ...
or calcium hydroxide
Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed or slaked with water. It has m ...
.
Other derivative uses
Many azo dye
Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N=N ...
s are produced from naphthalene. Useful agrichemical
An agrochemical or agrichemical, a contraction of ''agricultural chemical'', is a chemical product used in industrial agriculture. Agrichemical refers to biocides (pesticides including insecticides, herbicides, fungicides and nematicides) and syn ...
s include naphthoxyacetic acids.
Hydrogenation of naphthalene gives tetrahydronaphthalene ( tetralin) and decahydronaphthalene (decalin
Decalin (decahydronaphthalene, also known as bicyclo .4.0ecane and sometimes decaline), a bicyclic organic compound, is an industrial solvent. A colorless liquid with an aromatic odor, it is used as a solvent for many resins or fuel additives.
I ...
), which are used as low-volatility solvents
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for p ...
. Tetralin is used as a hydrogen-donor solvent.[
]Alkylation
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...
of naphthalene with propylene gives a mixture of diisopropylnaphthalenes Diisopropylnaphthalenes (DIPN) is a solvent for carbonless copy paper. The oil consists of a mixture of isomers of diisopropylnaphthalene. Some key properties are broad liquid range, low volatility, and low toxicity. DIN is also known as Kureha Mi ...
, which are useful as nonvolatile liquids for inks.[
Substituted napthalenes serve as pharmaceuticals such as propranolol (a beta blocker) and nabumetone (a ]nonsteroidal anti-inflammatory drug
Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...
).
Other uses
Several uses stem from naphthalene's high volatility: it is used to create artificial pores in the manufacture of high-porosity grinding wheels; it is used in engineering studies of heat transfer using mass sublimation
Sublimation or sublimate may refer to:
* ''Sublimation'' (album), by Canvas Solaris, 2004
* Sublimation (phase transition), directly from the solid to the gas phase
* Sublimation (psychology), a mature type of defense mechanism
* Sublimate of mer ...
; and it has been explored as a sublimable propellant for cold gas satellite thrusters.
Health effects
Exposure to large amounts of naphthalene may damage or destroy red blood cell
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
s, most commonly in people with the inherited condition known as glucose-6-phosphate dehydrogenase (G6PD) deficiency, which over 400 million people suffer from. Humans, in particular children, have developed the condition known as hemolytic anemia, after ingesting mothballs or deodorant blocks containing naphthalene. Symptoms include fatigue
Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...
, lack of appetite, restlessness, and pale skin. Exposure to large amounts of naphthalene may cause confusion, nausea
Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...
, vomiting
Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the Human nose, nose.
Vomiting can be the result of ailments like Food-poisoning, foo ...
, diarrhea
Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...
, blood
Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...
in the urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
, and jaundice
Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...
(yellow coloration of the skin due to dysfunction of the liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
).
The US National Toxicology Program
The National Toxicology Program (NTP) is an inter-agency program run by the United States Department of Health and Human Services to coordinate, evaluate, and report on toxicology within public agencies.
The National Toxicology Program is headqua ...
(NTP) held an experiment where male and female rats and mice were exposed to naphthalene vapors on weekdays for two years. Both male and female rats exhibited evidence of carcinogenesis
Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abnor ...
with increased incidences of adenoma
An adenoma is a benign tumor of epithelial tissue with glandular origin, glandular characteristics, or both. Adenomas can grow from many glandular organs, including the adrenal glands, pituitary gland, thyroid, prostate, and others. Some adenom ...
and neuroblastoma
Neuroblastoma (NB) is a type of cancer that forms in certain types of nerve tissue. It most frequently starts from one of the adrenal glands but can also develop in the neck, chest, abdomen, or spine. Symptoms may include bone pain, a lump in the ...
of the nose. Female mice exhibited some evidence of carcinogenesis based on increased incidences of alveolar Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit.
Uses in anatomy and zoology
* Pulmonary alveolus, an air sac in the lungs
** Alveolar cell or pneumocyte
** Alveolar duct
** Alveolar macrophage
* ...
and bronchiolar adenoma
An adenoma is a benign tumor of epithelial tissue with glandular origin, glandular characteristics, or both. Adenomas can grow from many glandular organs, including the adrenal glands, pituitary gland, thyroid, prostate, and others. Some adenom ...
s of the lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
, while male mice exhibited no evidence of carcinogenesis.
The International Agency for Research on Cancer
The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations.
Its role is to conduct and ...
(IARC) classifies naphthalene as possibly carcinogenic to humans and animals ( Group 2B). The IARC also points out that acute exposure causes cataracts in humans, rat
Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' ( pack rats), ''Bandicota'' (bandicoot ...
s, rabbit
Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit speci ...
s, and mice
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
; 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". A probable mechanism for the carcinogenic effects of mothballs and some types of air fresheners containing naphthalene has been identified.
Regulation
US government
The federal government of the United States (U.S. federal government or U.S. government) is the national government of the United States, a federal republic located primarily in North America, composed of 50 states, a city within a feder ...
agencies have set occupational exposure limits to naphthalene exposure. The Occupational Safety and Health Administration
The Occupational Safety and Health Administration'' (OSHA ) is a large regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. Congress established the agenc ...
has set a permissible exposure limit
The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits are established by the Occupational S ...
at 10 ppm (50 mg/m3) over an eight-hour time-weighted average. The National Institute for Occupational Safety and Health has set a recommended exposure limit at 10 ppm (50 mg/m3) over an eight-hour time-weighted average, as well as a short-term exposure limit at 15 ppm (75 mg/m3). Naphthalene's minimum odor threshold is 0.084 ppm for humans.
Mothballs and other products containing naphthalene have been banned within the EU since 2008.
In China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
, the use of naphthalene in mothballs is forbidden. Danger to human health and the common use of natural camphor
Camphor () is a waxy, colorless solid with a strong aroma. It is classified as a terpenoid and a cyclic ketone. It is found in the wood of the camphor laurel ('' Cinnamomum camphora''), a large evergreen tree found in East Asia; and in the k ...
are cited as reasons for the ban.
Naphthalene derivatives
The partial list of naphthalene derivatives includes the following compounds:
See also
*Camphor
Camphor () is a waxy, colorless solid with a strong aroma. It is classified as a terpenoid and a cyclic ketone. It is found in the wood of the camphor laurel ('' Cinnamomum camphora''), a large evergreen tree found in East Asia; and in the k ...
*Dialin
Dialin (1,2-dihydronaphthalene) is a hydrocarbon with the chemical formula C10H10. It is similar to naphthalene but one ring is partially saturated.
See also
* Naphthalene
* Tetralin
* Decalin
Decalin (decahydronaphthalene, also known as bicyc ...
, Tetralin, Decalin
Decalin (decahydronaphthalene, also known as bicyclo .4.0ecane and sometimes decaline), a bicyclic organic compound, is an industrial solvent. A colorless liquid with an aromatic odor, it is used as a solvent for many resins or fuel additives.
I ...
* List of interstellar and circumstellar molecules
*Mothballs
Mothballs are small balls of chemical pesticide and deodorant, sometimes used when storing clothing and other materials susceptible to damage from Mold (fungus), mold or moth larvae (especially clothes moths like ''Tineola bisselliella'').
Comp ...
*1-Naphthol
1-Naphthol, or α-naphthol, is a fluorescent organic compound with the formula . It is a white solid. It is an isomer of 2-naphthol differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are naphthalene homologues ...
, 2-Naphthol
* Sodium naphthalenide
*Wagner-Jauregg reaction The Wagner-Jauregg reaction is a classic organic reaction in organic chemistry, named after (son of Julius Wagner-Jauregg), describing the double Diels–Alder reaction of 2 equivalents of maleic anhydride with a 1,1-diarylethylene. After aromatiza ...
(classic naphthalene synthesis)
References
External links
Naphthalene
National Pesticide Information Center
EPA Air Toxics Web Site
mostly on toxicity of naphthalene
CDC – NIOSH Pocket Guide to Chemical Hazards
*
{{Authority control
Naphthalenes
Antiseptics
Hazardous air pollutants
IARC Group 2B carcinogens
Insecticides
Simple aromatic rings