What is "methyl tert-butyl ether"

n. (context organic compound automotive English) C₅H₁₂O ; an organic compound used to increase octane numbers of gasoline, through added oxygen, as an anti-knock additive

Methyl tert-butyl ether (also known as MTBE, tert-butyl methyl ether, tertiary butyl methyl ether and ''' tBME''') is an organic compound with molecular formula (CH)COCH. MTBE is a volatile, flammable, and colorless liquid that is sparingly soluble in water. It has a minty odor vaguely reminiscent of diethyl ether, leading to unpleasant taste and odor in water. MTBE is a gasoline additive, used as an oxygenate to raise the octane number. Its use is controversial in the US and declining in use in part because of its occurrence in groundwater and legislation favoring ethanol. However, worldwide production of MTBE has been constant at about 18 million tons/y (2005) owing to growth in Asian markets.