Abstract

Hydrocarbons, compounds of carbon and hydrogen, are structurally classified as aromatic and aliphatic; the latter includes alkanes (paraffins), alkenes (olefins), alkynes (acetylenes), and cycloparaffins. Hydrocarbons are important sources for energy and chemicals and are directly related to the gross national product. The United States has led the world in developing refining and petrochemical processes for hydrocarbons from crude oil and natural gas.

Hydrocarbons are used in the production of lubricants, in agriculture and food, in coatings, and in polymers. Toxicity and regulatory issues, including U.S. Clean Air Acts, the Clean Water Act, the Resource Conservation and Recovery Act, and others are discussed.

The focus of this article is on the first three members of the alkane family, methane, ethane, and propane; the two isomeric butanes; the three isomeric pentanes; hexanes; and cyclohexane. Their properties, manufacture, and uses are described.Natural gas is the principal source of methanes, ethanes, and propane. Butanes are recovered from natural gas and petroleum refining streams. Pentanes occur in straight-run gasoline and certain refining streams. Hexane and cyclohexane can be obtained from crude oil. High purity cyclohexane is made by hydrogenation of benzene.Principal uses of the alkanes are as fuels and as raw materials for essential chemical intermediates, notably ethylene from ethane and propane and nylon precursors from cyclohexane.