Commercial petroleum products, such as gasoline, kerosene, airplane fuel, lubricating oils, and paraffin, are mixtures of hydrocarbons. Some hydrocarbons are found in coal tar and coal gas. Hydrocarbons are starting materials for the petrochemical industry. Petrochemical companies use hydrocarbons from crude oil and natural gas to manufacture solvents, plastics, and synthetic fibers and rubbers. Hydrocarbons can be divided into three large classes.
Aliphatic hydrocarbons have the principal carbon atoms arranged in chains.
They are further divided into the paraffin, olefin, and acetylenic series. Paraffins, or alkanes, include the greatest number of hydrocarbon compounds. Methane is the first member of the series. Others include ethane and propane. Paraffins react by substitution.