Acenaphthylene, a

polycyclic aromatic hydrocarbon A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. ...

is an ortho- and peri-fused tricyclic hydrocarbon. The molecule resembles

naphthalene Naphthalene is an organic compound with formula . 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. As an aromat ...

with positions 1 and 8 connected by a -CH=CH- unit. It is a yellow solid. Unlike many

polycyclic aromatic hydrocarbons A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. P ...

, it has no

fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, ...

Occurrence

Acenaphthylene occurs as about 2% 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 psoria ...

. It is produced industrially by gas phase dehydrogenation of

acenaphthene Acenaphthene is a polycyclic aromatic hydrocarbon (PAH) consisting of naphthalene with an ethylene bridge connecting positions 1 and 8. It is a colourless solid. Coal tar consists of about 0.3% of this compound. Production and reactions Acena ...

Reactions

Hydrogenation 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 org ...

gives the more saturated compound

. Chemical reduction affords the radical anion sodium or potassium acenaphthalenide, which is used as a strong reductant (E = -2.26 V vs FC).N. G. Connelly and W. E. Geiger, "Chemical Redox Agents for Organometallic Chemistry", Chem. Rev. 1996, 96, 877-910. It functions as a ligand for some organometallic compounds.

Uses

Polymerisation of acenaphthylene with acetylene in the presence of a Lewis acid catalyst gives electrically conductive polymers. Acenaphthylene possesses excellent properties as an antioxidant in cross-linked polyethylene and ethylene-propylene rubber. Thermal trimerization of acenaphthylene leads to decacyclene, which can be further processed to sulfur dyes.

Toxicity

The no-observed-effect-level of acenaphthylene after repeated 28-day oral administration to both male and female rats was found to be 4 mg/kg/day.

References

{{Authority control Polycyclic aromatic hydrocarbons Tricyclic compounds