OCTANE RATING OF GASOLINE

Scientists discovered that branched chain structure of hydrocarbon produced a very high performance..A compound known as iso--octane was discovered to be the best performance and was assigned a value of 100octane..
an unbranched compound known as heptane was found to cause a bad luck in engines and was given an octane rating of 0[zero].. A gasoline rated 90 was the one that performed the same way as 90percent iso--octane and 10 heptane..
it was also discovered that the octane rating can be improved by heating gasoline in the presence of catalyst such as sulphuric acid and ALCL3..the greater in the increase is attributed to conversion of some part of the unbranched to a highly branched.

octane boosters
To boost the ocatne rating of gasoline..substances
known as octane boosters are employed e.g pb--tetra ethyl..they increased the anti knocking properties of fuel even when added in small quantities.but pb is said to cause great hazzards to the body and to the environment in general.. it also fowls tha catalytic converter used in modern automobiles..that is why it is phased out as an ocatne booster..petroleum industry now use catalytic reformation to convert octane alkane to a high ocatne aromatic compound..

hexane with an octane no of 25 is converted to benzene with an ocatne no of 106,so many ocatne boosters have been dicovered but none is as effective as pb--tetra ethyl therefore they rae used in large quantities..they are also associated with solubility problems..