This page creation was supported with funds from the Wilson Education Grant Award from the College of Earth and Mineral Sciences. The intention is to provide students a better understanding of chemical structures related to Fuel and Energy issues. If you have suggestions for other structures please email them to me and please fill out the evaluation form.

Gasoline is known as Petrol in the England, and Benzene in France.

Iso-Octane


The octane that we know from filling our tanks is actually 2,2,4 trimethyl pentane. The octane number relates to the knocking (premature ignition) of the fuel, specifically an 87 octane gasoline has the same knocking properties as a mixture of 87% octane and 13% heptane (octane number of zero). The (R+M/2) indicates that the knocking is averaged over two engine conditions. It does not imply that the composition of the gasoline is 87% "octane".


Heptane


This has an octane number of zero and is used in comparing actual fuels with an octane/heptane mixture to calculate the octane number. It is an normal (meaning straight chain) alkane. Long chain alkanes are undesirable in gasoline because of their knocking properties. They can be cracked either thermally or with a catalyst to increase the gasoline yield.

MTBE


In the process of being removed from gasoline because of contamination of ground water (it imparts a foul taste and odor at very low levels of contamination). It was put in to oxygenate the fuel (greater than 2.7% oxygen by weight) to reduce carbon monoxide production in the winter months and reduce ozone forming compounds in the non-attainment areas in the summer months.

CETANE


The diesel equivalent to an octane number is the cetane number (16 carbon atom straight chain alkane). Longer chain alkanes freeze at a lower temperature than shorter chains and this can be a problem in very cold climates.

1-Methyl-Naphthalene


This has a cetane number of zero.

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