Toluene aromatic hydrocarbon industrial applications - WorldOfChemicals

Toluene - additive for racing fuels, fuel octane booster

Category : General Chemicals
Published by : Data Research Analyst,

Toluene is an aromatic hydrocarbon solvent often referred as methylbenzene. Toluene is widely used in industry, often served as a substitute for benzene. Methyl side groups present in toluene makes toluene metabolized differently than benzene.


Toluene is well absorbed through the lung, with an alveolar retention of 40 to 80 per cent of an inhaled dose. Air-borne exposure to toluene vapor represents a significant concern to both industrial workers and consumers. Current standards for a permissible exposure limit for toluene at 100 ppm.


Toluene is produced during the process of making gasoline and other fuels from crude oil, in making coke from coal, and as a by-product in the manufacture of styrene. Toluene has numerous commercial and industrial applications and is a solvent in paints, lacquers, thinners, glues, correction fluid and nail polish remover, and is used in the printing and leather tanning processes. Due to its easy accessibility, low cost and ease of concealment, some U.S. states have placed restrictions on the sale of these products to minors.


Toluene is used as a solvent, especially for paints, coatings, gums, oils and resins, and as raw material in the production of benzene, phenol and other organic solvents and in the production of polymers and rubbers. Most amounts of toluene (in the form of benzene-toluene-xylene mixtures) are used in the blending of petrol and it also occurs as a by-product of styrene manufacture.


Toluene is a pure hydrocarbon (C7H8) contains only hydrogen and carbon atoms. It belongs to a particular category of hydrocarbons called aromatic hydrocarbons. Complete combustion of toluene yields two different types of products like carbon dioxide (CO2) and water (H2O). There are no metallic compounds (lead, magnesium etc), no nitro compounds and no oxygen atoms in toluene. Toluene is made up of exactly the same ingredients as ordinary gasoline.


Octane rating/octane number

Octane rating or octane number is a standard measure of the performance of a motor fuel or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating. In broad terms, fuels with a higher octane rating are used in high-compression engines that generally have higher performance. In contrast, fuels with lower octane numbers are ideal for diesel engines.

The octane number in vehicles mentioned as Anti-Knock Index (AKI). It’s an average of two octane ratings using the same test equipment but using different operating conditions. The methods produce a Research Octane number (RON) and a Motor Octane Number (MON). With modern engines and fuels systems, recent studies have shown that RON is more important than MON. So in these cars, the higher the RON the better these cars perform. This difference is called sensitivity.


Toluene applications in vehicle additives

Toluene has a RON octane rating of 121 and a MON rating of 107, leading to a (R+M)/2 rating of 114. (R+M)/2 are how ordinary fuels are rated in the US. Toluene has a sensitivity rating of 14 (RON: 121-107 MON). This compares favorably with alcohols, which have sensitivities in the 20 to 30 range. The more sensitive a fuel is the more its performance degrades under load. Toluene's low sensitivity means that it is an excellent fuel for a heavily loaded engine.


Toluene is denser than ordinary gasoline and contains more energy per unit volume. Thus combustion of toluene leads to more energy being liberated and thus more power generated. This is in contrast to oxygenated octane boosters like ethanol or Methyl Tertiary Butyl Ether (MTBE), which contain less energy per unit volume compared to gasoline. The higher heating value of toluene also means that the exhaust gases contain more kinetic energy, which in turn means that there is more energy to drive turbocharger vanes.


Toluene is such an effective anti knock fuel that it takes a smaller quantity to achieve the same octane boost compared to 100 octane racing gas.


Toluene is such an effective anti knock fuel it also means that it is more difficult to ignite at low temperatures. The Formula 1 cars that ran on 84 per cent toluene needed to have hot radiator air diverted to heat its fuel tank to 70oC to assist its vaporization. Thus too strong a concentration of toluene will lead to poor cold start and running characteristics. It’s recommended that the concentration of toluene used not to exceed 30 per cent or what the engine is capable of utilizing.



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