Isooctane: The Standard Reference Substance for Gasoline Octane Rating

What is Octane Rating?

Octane rating is a measure of a gasoline's anti-knock properties. Anti-knock property refers to the fuel's ability to resist explosive or knocking combustion under various operating conditions. Engine knock is an abnormal combustion phenomenon that can lead to reduced engine power, increased fuel consumption, and damage to engine parts. A higher octane rating indicates better anti-knock performance, allowing the engine to use a higher compression ratio, which in turn improves power output and fuel economy.

The Standard Reference Substance

Isooctane, also known as 2,2,4-trimethylpentane, is a standard reference substance for studying gasoline octane rating. It is a colorless, transparent liquid with the chemical formula C₈H₁₈ and a molecular weight of 114.23. It has high anti-knock performance and is used as the standard reference substance for studying gasoline octane ratings.

Physical and Chemical Properties

• Physical Properties: Isooctane is a liquid at room temperature and is highly volatile. Its density is 0.692 g/mL at 25°C , its boiling point is 98-99°C, and its melting point is -107°C.

• Chemical Properties: It is chemically stable. It does not react with 95% sulfuric acid. At 140°C, a nitration reaction occurs in a mixed acid of nitric and sulfuric acid. It is more susceptible to oxidation than octane due to the presence of a hydrogen atom on the tertiary carbon. It can undergo photochemical reactions with halogens and alkylation reactions with olefins.

• Solubility: It is insoluble in water and slightly soluble in alcohol. It is miscible with ethers, ketones, benzene, toluene, xylene, chloroform, carbon tetrachloride, carbon disulfide, and dimethylformamide.

Main Uses

• Standard Fuel: Isooctane is used as a standard fuel for determining the octane value of gasoline. Its octane value is 100.

• Fuel Additive: Isooctane can be used as an additive for high-grade gasoline and aviation gasoline. It improves the anti-knock properties of gasoline, enhances combustion performance, and reduces tailpipe emissions.

• Solvent: Isooctane can also be used as a solvent in organic synthesis reactions to dissolve various organic compounds.

Handling and Storage Precautions

Isooctane is classified as a Class 1 flammable liquid. Its hazardous regulation number is 61011. Keep away from all sources of ignition. In case of fire, use foam, carbon dioxide, or dry powder extinguishers.

It is not corrosive to metals and can be stored in containers made of mild steel, copper, or aluminum. Due to its swelling effect on natural rubber and some synthetic rubbers, suitable gaskets and seals must be selected. It is considered to have low toxicity.

Isooctane should be stored in a cool, dry, and well-ventilated area, away from fire and high temperatures. During transportation, prevent violent vibrations and collisions to avoid package damage and leaks. It should be stored away from oxidizing agents and acids/bases to ensure product quality and safety.

Conclusion

Overall, isooctane is an important fuel additive and solvent with a wide range of applications in the fuel and chemical industries. Understanding its properties, uses, and handling methods helps in better managing this compound and ensures smooth experimental and production processes.