Tetraethyl lead is an organometallic compound with the chemical formula (C₂H₅)₄Pb. In 1922, automotive engineers found that the addition of a small amount of this compound to gasoline improves engine performance and reduces knocking. Knocking is a physical phenomenon that results when low-octane gasoline is burned in an internal combustion engine. Until 1975, tetraethyl lead was the most common additive used to reduce knocking in motor fuels. This additive presents an environmental hazard, however, since lead is expelled into the environment during operation of automobile engines using leaded fuels. Given the growing concern about the health effects of lead, the compound has now been banned for use in gasolines in the United States.

See Also

Air Pollution; Air Pollution Index; Emission; Gasohol