The current position锛Home > Products
PRODUCT
PRODUCT
  • Naphthalene
  • Product overview锛Naphthalene is an organic compound with formula C 10H 8. It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass.[10] As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is best known as the main ingredient of traditional mothballs.

    Quality index锛鍥芥爣

    Risk rating锛鍏锋湁鍒烘縺浣滅敤锛岄珮娴撳害鑷存憾琛鎬ц传琛鍙婅倽銆佽偩鎹熷銆

    Packaging specifications锛50鍏枻/绾告澘妗
  • Online ordering
The main characteristics of

History[edit]

In the early 1820s, two separate reports described a white solid with a pungent odor derived from the distillation of coal tar. 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 (a broad term encompassing any volatile, flammable liquid hydrocarbon mixture, including coal tar).[11] Naphthalene's chemical formula was determined by Michael Faraday in 1826. The structure of two fused benzene rings was proposed by Emil Erlenmeyer in 1866,[12] and confirmed by Carl Gr盲bethree years later.

Structure and reactivity[edit]

A naphthalene molecule can be viewed as the fusion of a pair of benzene rings. (In organic chemistry, rings are fused if they share two or more atoms.) As such, naphthalene is classified as a benzenoid polycyclic aromatic hydrocarbon (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, the carbon鈥揷arbon bonds in naphthalene are not of the same length. The bonds C1鈥揅2, C3鈥揅4, C5鈥揅6 and C7鈥揅8 are about 1.36 脜 (136 pm) in length, whereas the other carbon鈥揷arbon bonds are about 1.42 脜 (142 pm) long. This difference, which was established by X-ray diffraction[citation needed], is consistent with the valence bond model of bonding in naphthalene that involves three resonance structures (as shown below); whereas the bonds C1鈥揅2, C3鈥揅4, C5鈥揅6 and C7鈥揅8 are double in two of the three structures, the others are double in only one.

  • Resonance structures of naphthalene

Like benzene, naphthalene can undergo electrophilic aromatic substitution. For many electrophilic aromatic substitution reactions, naphthalene reacts under milder conditions than does benzene. For example, whereas both benzene and naphthalene react withchlorine in the presence of a ferric chloride or aluminium chloride catalyst, naphthalene and chlorine can react to form 1-chloronaphthalene even without a catalyst. Likewise, whereas both benzene and naphthalene can be alkylated using Friedel鈥揅rafts reactions, naphthalene can also be alkylated by reaction with alkenes or alcohols, with sulfuric or phosphoric acid as the catalyst.

Substituted derivatives[edit]

Two isomers 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 掳C, and the 2-isomer at 160 掳C.

Naphthalene can be hydrogenated under high pressure in the presence of metal catalysts to give 1,2,3,4-tetrahydronaphthalene ortetralin (C
10
H
12
). Further hydrogenation yields decahydronaphthalene or decalin (C
10
H
18
). Oxidation with chromate or permanganate, or catalytic oxidation with O
2
 and a vanadium catalyst, gives phthalic acid.

Production[edit]

Most naphthalene is derived from coal tar. 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 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 acidic components (chiefly various phenols), and with sulfuric acid to remove basic components, undergoes fractional distillation 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 (0.2%),indene (< 2%), and methylnaphthalene (< 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 掳C (melting point). Approximately 1.3M tons are produced annually.[13]

In North America, coal tar producers are Koppers Inc., Ruetgers Canada Inc. and Recochem Inc., and petroleum-derived producer is Advanced Aromatics, L.P. In Western Europe most known producers are Koppers, Ruetgers and Deza. In Eastern Europe, - variety of integrated metallurgy complexes (Severstal, Evraz, Mechel, MMK) in Russia. Dedicated naphthalene and phenol maker INKOR and Yenakievsky Metallurgy plant in Ukraine, and ArcelorMittal Temirtau in Kazakhstan.

Other sources and occurrences[edit]

Aside from coal tar, trace amounts of naphthalene are produced by magnolias and specific types of deer, as well as the Formosan subterranean termite, possibly produced by the termite as a repellant against "ants, poisonous fungi and nematode worms."[14] Some strains of the endophytic fungus Muscodor albus produce naphthalene among a range of volatile organic compounds, while Muscodor vitigenus produces naphthalene almost exclusively.[15]

Naphthalene has been found in meteorites.

Naphthalene in the interstellar medium[edit]

Naphthalene has been tentatively detected in the interstellar medium in the direction of the star Cernis 52 in the constellationPerseus.[16][17] More than 20% of the carbon in the universe may be associated with polyaromatic hydrocarbons, including naphthalene.[18]

Protonated cations of naphthalene (C
10
H+
9
) are the source of part of the spectrum of the Unidentified Infrared Emissions (UIRs). Protonated naphthalene differs from neutral naphthalene (e.g. that used in mothballs) in that it has an additional hydrogen atom. The UIRs from "naphthalene cation" (C
10
H+
8
) have been observed by astronomers. This research has been publicized as "mothballs in space."[19]

Uses[edit]

As a chemical intermediate[edit]

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.[13]

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鈥揳cid battery plates.

Naphthalene sulfonate polymers are produced by treating 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.

  • H
    2
    SO
    4
     + C
    10
    H
    8
     鈫 C
    10
    H
    7
    -SO
    3
    H
     + H
    2
    O

  • C
    10
    H
    7
    -SO
    3
    H
     + n CH
    2
    =O 鈫 SO
    3
    H-C
    10
    H
    7
    -(-CH
    2
    -C
    10
    H
    7
    -SO
    3
    H)
    n
     + n H
    2
    O

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

  • C
    10
    H
    7
    -SO
    3
    H-(C
    10
    H
    7
    -SO
    3
    H)
    n
     + m H
    2
    SO
    4
     + n+2m NaOH 鈫 C
    10
    H
    7
    -SO
    3
    Na-(C
    10
    H
    7
    -SO
    3
    Na)
    n
     + n H
    2
    O
     + m Na
    2
    SO
    4

As a solvent for chemical reactions[edit]

Molten naphthalene provides an excellent solubilizing medium for poorly soluble aromatic compounds. In many cases it is more efficient than other high-boiling solvent, such as dichlorobenzenebenzonitrilenitrobenzene and durene. A reaction of C60 with an equimolar amount of anthracene in refluxing naphthalene gives the 1:1 Diels-Alder adduct in 67% yield.[20]

  • Reaction of C60 with anthracene.tif

A procedure developed for aromatization of porphyrins includes heating with DDQ in naphthalene melt. It was shown that naphthalene not only provides sufficient solubility of reactants but has an influence on a selectivity of the process.[21]

  • Aromatization of porphyrin in naphthalene melt.tif

About|Product|Service|Contact|Map|Micro-blog|WeChat
CopyRight 2014-2018,All Rights Reserved Hangzhou Chuyuan Chemical Limited company 娴橧CP澶05005622鍙