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Category: Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons are a group of chemicals that occur naturally in coal, crude oil, and gasoline. PAHs are also present in products made from fossil fuels, such as coal-tar pitch, creosote, and asphalt. When coal is converted to natural gas, PAHs can be released. Therefore, some coal-gasification sites may have elevated levels of PAHs. PAHs also can be released into the air during the burning of fossil fuels, garbage, or other organic substances. The less efficient the burning process, the more PAHs are given off. Forest fires and volcanoes produce PAHs naturally.


Acenaphthylene is an ethylene containing polycyclic aromatic hydrocarbon. It is an ingredient used in preparing coal tar.

Chemical Properties of Acenaphthylene

Know all about the chemical properties of this substance:-

Chemical Formula

The chemical formula for this chemical is C12H8.

Boiling Point

The boiling point for this chemical is at 280 °C.

Melting Point

The melting point of this chemical is at 92-93 °C.

Molecular Weight

The molecular weight of this chemical is 152.20 g/mol.


The density of this chemical is 0.899 g/cm3.

Physical Properties of Acenaphthylene

This substance generally occurs as a yellow or colorless crystalline powder.


The substance is soluble in a wide variety of compounds including methanol, ethanol, ether, alcohol, benzene and petroleum ether. It is insoluble in water.


This is a stable compound, though it is not compatible with oxidizing agents.


Acenaphthylene can react violently with other hydrocarbons and can even give rise to explosions. The chemical reacts exothermically with diazo compounds and bases. The benzene nucleus can be changed by a halogenation reaction and acid catalysts. Other factors contributing to this effect are the Friedel-Crafts reaction, sulfonation and nitration. The substance can have a direct photolysis reaction in water under the influence of sunlight. A reaction with carbon monoxide or carbon dioxide can produce a hazardous decomposition.


This chemical is inflammable and prone to causing fire accidents if not stored or handled carefully.


Even though this chemical compound is a polycyclic aromatic hydrocarbon, unlike most of its kind, it has got no fluorescent properties.


The molecule of the chemical has a three-ring structure. Two of the rings are hexagonal and one is pentagonal.

Molecular Structure of Acenaphthylene – C12H8

Picture 1 – Molecular Structure of Acenaphthylene

Synthesis of Acenaphthylene

The compound is produced during combustion of natural fibers. It can be produced from 1-Acetoxyacenaphthene (C14H12O2) and 4-Amino-1,8-Naphthalimide (C12H8N2O2). It is a common ingredient in coal tar and crude oil. It is also often produced as an industrial or municipal waste. Coal tar distillation is another way of producing this substance.

Uses of Acenaphthylene

The chemical compound is used in the production of materials like

  • Dyes
  • Pigments
  • Soaps
  • Pesticides (such as fungicides, herbicides and insecticides)

It is also used in manufacturing plastic.

Material Safety Data Sheet (MSDS)s of Acenaphthylene

The chemical is commonly released in the environment by disposal of factory and industrial sewage and waste byproducts. This substance is also produced by coal tar distillation.

Humans are generally infected by this compound by inhalation or dermal contact where the content of this chemical is high. The chemical exists as vapor in the air. Drinking water supplies can also get contaminated by this chemical and prove to be a health hazard for humans. People swimming or taking baths in water contaminated with this chemical can also get infected. This can lead to health disorders such as skin cancer.

Toxicology of Acenaphthylene

Toxicology data on this substance shows that it is harmful to health if it is swallowed or inhaled or absorbed by skin. Exposure to the eyes or the respiratory organs can cause subsequent irritation and health damage. A person might suffer from lung cancer if his or her respiratory organs are exposed to this chemical.

The compound goes through biodegradation in the surrounding environment.

Critical Areas of Acenaphthylene Infection

The areas that are most vulnerable to infection include

  • Lungs
  • Skin
  • Eyes
  • Nervous system
  • Mucous membranes

Safety Measures for Acenaphthylene

Human eyes, on direct contact with this substance, can suffer from irritation. In such cases, the eyes should be splashed with lots of water for at least fifteen minutes. A doctor should be consulted for a checkup.

If the skin gets in contact with this chemical, the clothes should be removed and the infected areas should be washed with water. Medical help should be taken for precaution. The clothes should be washed before wearing them again.

If the chemical is swallowed, a doctor should be consulted and unless recommended by the doctor, vomiting should not be induced.

If this chemical is inhaled, a person should immediately move to a place with fresh, pure air. If that does not help in proper breathing, artificial respiration should be used.

Fire Safety Measures

Toxic gases and irritants may be released during a combustion or thermal decomposition of this chemical compound. Carbon dioxide, dry chemical or foam should be used to put off the fire. A breathing apparatus, approved by MSHA/NIOSH, should be worn while dealing with a fire caused by this compound.

Exposure Safety Measures

Proper safety gear including eyewear, gloves and breathing gear should be used to dispose of any leakage of this material.

Degradation of Acenaphthylene

This chemical can be degraded by biodegrading agents. The bacterium Rhizobium special strain CU-A1 can be used for this purpose.

Oxidation is another process of degrading this chemical. Oxidizing agents such as Ozone and Hydrogen peroxide can be used to degrade this compound.

Thermal Dimerization of Acenaphthylene

The methods of obtaining E-heptacyclene or Z-heptacyclene under the influence of Acenaphthylene thermal dimerization were investigated in a recent study. The conclusions derived from the experiments inferred that acenaphthylene thermal dimerization at 298.15 K is exergonic and exothermic in gaseous and solid conditions.

This is an important chemical used for manufacturing insecticides that are required for domestic purposes. Hence, people are often found to live in close proximity to this chemical. It is thus important to take adequate care so as to avoid any contamination which could result in serious health issues.







Definition of Acenaphthene

Acenaphthene is a polycyclic aromatic hydrocarbon with an ethylene bridge linking 1 and 8 site.

Other Names for Acenaphthene

This hydrocarbon is also known by other names like

  • Acenaphthylene
  • 1,2-Dihydroacenaphthylene
  • 1,8-Ethylenenaphthalene
  • Peri-Ethylenenaphthalene
  • Aphthyleneethylene

Molecular Formula of Acenaphthene

Its molecular formula is C12H10.

Solubility of Acenaphthene

The solubility of this substance in water is 0.4 mg/100 ml.

Boiling Point of Acenaphthene

The boiling point for Acenaphthene is 279 °C (552 K, 534 °F).

Chemical Facts of Acenaphthene

Some key chemical statistics on Acenaphthene are:

  • Density: 1.222
  • Melting Point: 93.4 °C (367 K, 200 °F)
  • Vapor Pressure: 0.3 (Pa at 25°C)
  • Relative Vapor Density: 5.3 (air=1).
  • Flash Point: 135°C o.c.
  • Auto-Ignition Temperature: > 450 °C
  • Half Life: Biodegradation in Aerobic Soil Varies from less than 10 to 102 days
Structure of Acenaphthene – C12H10

Picture 1 – Structure of Acenaphthene
Source – needpix.com

Other Facts and Identification Features

Some of the other important facts and identification features of this substance are:

  • It appears as white beige in color.
  • This substance exists as a pure ingredient as well as constituent of polyaromatic hydrocarbon (PAH) mixture.
  • It is a component of coal tar.
  • Its alternative name 1, 2-Dihydroacenaphthylene underlines that it is a hydrogenated form of Acenaphthylene.
  • It does not have fluorescence, which is quite contrary to most polycyclic aromatic hydrocarbons.

Material Safety Data Sheet (MSDS) of Acenaphthene

It is a combustible substance. Its powdered particles can lead to dust explosions with air. There is a risk that on combustion, it could lead to formation of contaminated gases like Carbon Monoxide. This substance reacts with strong oxidants.

Sources of Human Exposure

Human beings are exposed to it by inhalation of its aerosol, skin contact or by ingestion. Its odor detection in air is 8.0X10-2 ppm (chemically pure). Threshold odor concentration in water at room temperature is 0.08 ppm (range 0.02 to 0.22 ppm) with odor low of 0.5048 mg/cu m, and odor high 0.5048 mg/cu m.

This substance has been found in drinking water. It is reported that two of five samples of Nordic tap water in US included Acenaphthene at a concentration of 7.4 – 14.0 ng/l. In an investigation of drinking water supplies in the UK, Acenaphthene was detected at 2 of 14 water facilities.

Health Implications on Exposure

On inhalation, a damaging absorption of airborne particles can be attained rapidly when scattered. Studies have shown exposure to this substance can lead to cancer and adverse effects on the cardiovascular system.

First Aid

In case of inhalation, shift to a place with abundant fresh air and take rest. If your skin has been exposed to this chemical, remove polluted clothes and wash skin thoroughly. For eyes, first rinse with plenty of fresh water (after removing lens) before consulting a doctor. In case of ingestion, rinse mouth thoroughly.

Precautions for Operators

Those working with it are advised to carry their operations under dust and explosion-proof electrical equipment and lighting. For preventing dispersion of dust, use of protective gloves and safety goggles is recommended. It is also important not to eat, drink or smoke while working with this substance. In case of a fire caused by this substance, the situation can be brought in control with the aid of

  • Water
  • Dry powder
  • Foam
  • Carbon Dioxide

Storage Precautions

This substance should be stored in a place away from strong oxidants. There should be adequate fire extinguishers to tackle any mishaps. Also, its inventory should be kept away from drain or sewer access.

Environmental Safeguards for Acenaphthene Toxicity

As this substance is toxic to aquatic organisms, it is important to make sure that Acenaphthene does not enter the aquatic environment as well as over-all environment. It is important for authorities to make sure that drinking water is free from this substance.






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