Fact sheet: 2-methylnaphthalene

General information

CAS number

91-57-6

Molecular formula

C₁₁H₁₀

Formula weight

142.2 g/mol

Family

Monocyclic aromatic hdrocarbons (MAH)

Properties (at room temperature where applicable)

Environmental behaviour

At 20 ⁰C, 2-methylnaphthalene is a solid with a relative density at the limits of floating or sinking in water. It is characterized by low volatility, low solubility, and once dissolved, it volatilizes moderately while adsorbing strongly to organic matter. When present in soil, it volatizes partially and dissolves slowly. Once dissolved, 2-methylnaphthalene can reach the water table or migrate into a waterway, where it will be diluted before partially volatilizing. Fragments of 2-methylnaphthalene can also be carried into a waterway, where they will either disperse on the surface or be deposited at the bottom, and then slowly dissolve. Once the source has been removed, the adsorbed phase will take a very long time to disappear, liberating contamination in either the gaseous or dissolved state.

Health and safety

2-Methylnaphthalene should be handled with care as it is toxic.

Principal resources

2-Methylnaphthalene is a polycyclic aromatic hydrocarbon (PAH). PAHs are a group of organic compounds that contain two or more benzene rings in their structure. There are more than 100 different PAHs that generally occur as complex mixtures (example, combustion by-products such as soot). Incomplete combustion of fuels in engines, during coal coking, or when wood is burning (forest fires, wood stoves) produces PAHs. PAHs are also constituents of petroleum and coal, and they are more present in some of their derivatives like tars and asphalt. The wood preservative industry (example, creosote), aluminum smelters using Soderberg electrodes, and hazardous waste disposal sites are further contributors of anthropogenic PAHs to the environment.

2-Methylnaphthalene may be obtained from coal tar. It is used in vitamin K production, in the preparation of some insecticides and brightnening agents, and as a chemical in biochemical or cancer research. It can also be chlorinated and oxidized to form dyes, and small amounts in sulfonated form are used as textile aids, wetting agents and emulsifiers. 2-Methylnaphthalene is most likely to be found mixed with other PAHs in commercial products like coal tar, coal tar pitch, creosote, bitumen and asphalt. Coal tar is used as a fuel in the steel industry, distilled to give coal tar pitch and creosote, and has been used in the clinical treatment of skin disorders such as eczema and dermatitis. Coal tar pitch is used primarily as a binder for aluminum smelting electrodes, but is also used in roofing, surface coatings and a variety of other applications. Creosote is used to preserve wood for railroad ties, marine pilings and telephone poles. Some creosote products are also used as a fuel by steel production. Bitumen and asphalt are used for paving roads, for sound- and water-proofing, and coating pipes.

References

Agency for Toxic Substances and Disease Registry (ATSDR). 2005. Toxicological Profile for Naphthalene, 1-Methylnaphthalene, and 2-Methylnaphthalene. U.S. Department of Health and Human Services, Public Health Service, Georgia, USA. (Viewed December 2013)

Canadian Council of Ministers of the Environment. 1999. Canadian Water Quality Guidelines for the Protection of Aquatic Life: Polycyclic Aromatic Hydrocarbons (PAHs). In: Canadian Environmental Quality Guidelines. Canadian Council of Ministers of the Environment, Manitoba, Canada. (Viewed December 2013)

Montgomery, John H. 2007. Groundwater Chemicals, Desk Reference, Fourth Edition, CRC Press, Taylor and Francis Group, Florida, USA.

National Toxicology Program. 2005. Report on Carcinogens, Twelfth Edition: Substance Profile of Polycyclic Aromatic Hydrocarbons. U.S. Department of Health and Human Services, Public Health Services, USA.(PDF, 142KB) (Viewed December 2013)