Tetraethyl lead

Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula Pb(C2H5)4. It was widely used as a fuel additive for much of the 20th century, first being mixed with gasoline beginning in the 1920s. This "leaded gasoline" had an increased octane rating that allowed engine compression to be raised substantially and in turn increased vehicle performance and fuel economy. TEL was first synthesized by German chemist Carl Jacob Löwig in 1853. American chemical engineer Thomas Midgley Jr., who was working for the U.S. corporation General Motors, was the first to discover its effectiveness as a knock inhibitor on 9 December 1921, after spending six years attempting to find an additive that was both highly effective and inexpensive. Of the some 33,000 substances in total screened, lead was found to be the most effective antiknock agent, in that it necessitated the smallest concentrations necessary; a treatment of 1 part TEL to 1300 parts gasoline by weight is sufficient to suppress detonation. The four ethyl groups in the compound served to dissolve the active lead atom within the fuel. When injected into the combustion chamber, tetraethyllead