Toluene aromatic hydrocarbon solvent often served as a substitute for benzene find various industrial applications such as octane booster, fuel additive, coatings, rubber and polymers

1. Toluene as octane
booster, vehicle additive
Article written and published
By
www.worldofchemicals.com

2. Introduction
• 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.

3. Toluene Production
• 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.

4. Toluene Industrial applications
• 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.

5. Toluene as octane ratings
• 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.

6. 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: 121107 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.

7. Toluene applications in vehicle
additives
• 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.