C10H8, melting point 80°C. A white, waxy solid, containing two fused benzene rings; obtained from the distillation of coal tar. It forms many derivatives, and is important as a starting material in the synthesis of dyestuffs and plastics. It is familiar as the main ingredient of mothballs.
| Naphthalene | |
|---|---|
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| General | |
| Chemical name | Naphthalene |
| Other names |
Tar Camphor, White Tar, Moth Flakes |
| Chemical formula | C10H8 |
| SMILES | C1(C=CC=C2)=C2C=CC=C1 |
| Molar mass | 128.17052 g/mol |
| Appearance |
White solid crystals/flakes, strong odor of coal tar |
| CAS number | 91-20-3 |
| Properties | |
| Density | 1.14 g/cm³ |
| Solubility in water | Insoluble in water |
| Melting point | 80.5 °C |
| Boiling point | 218 °C |
| Hazards | |
| MSDS | External MSDS |
| Main hazards |
Flammable, sensitizer, possible carcinogen. Dust can form explosive mixtures with air |
| NFPA 704 | 2 2 0 |
| Flash point | 79 - 87 °C |
| Autoignition temperature | 525 °C |
| R/S statement |
R: 20, 21, 22, 36, 37, 38, 43, 45 S: 16, 26, 36, 37, 39, 45 |
| RTECS number | QJ0525000 |
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Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references |
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Naphthalene (not to be confused with naphtha) (also known as naphthalin, naphthaline, tar camphor, white tar, albocarbon, or naphthene), is a crystalline, aromatic, white, solid hydrocarbon, best known as the primary ingredient of mothballs.
Structure and reactivity
A naphthalene molecule is composed of two fused benzene rings. For example, while both benzene and naphthalene react with chlorine in the presenece of a ferric chloride or aluminium chloride catalyst, naphthalene and chlorine can react to form 1-chloronaphthalene even without a catalyst. Similarly, while both benzene and naphthalene can be alkylated using Friedel-Crafts reactions, naphthalene can also be alkylated by reaction with alkenes or alcohols, with sulfuric or phosphoric acid as the catalyst.
Mono-substitution of naphthalene has two possible isomeric products, corresponding to substitution at an alpha or beta position, respectively.
Production
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. While the composition of coal tar varies with the coal from which it is produced, typical coal tar is about 10% naphthalene by weight. The crude naphthalene resulting from this process is about 95% naphthalene by weight. Where purer naphthalene is required, crude naphthalene can be further purified by recrystallizing it from any of a variety of solvents.
Incidence in nature
Trace amounts of naphthalene are produced by magnolias and specific types of deer.
Uses
Naphthalene's most familiar use is as a household fumigant, such as in mothballs. In a sealed container containing naphthalene pellets, naphthalene vapors build up to levels toxic to both the adult and larval forms of many moths that are destructive to textiles. The single largest use of naphthalene is the industrial production of phthalic anhydride, although more phthalic anhydride is made from o-xylene than from naphthalene.
Health effects
In humans, exposure to large amounts of naphthalene may damage or destroy red blood cells.
When the U.S. National Toxicology Program exposed male and female rats and mice to naphthalene vapors on weekdays for two years (1), 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.
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