Ethers
DETAIL
Production and properties
MTBE is manufactured via the chemical reaction of methanol and isobutylene. Methanol is primarily derived from natural gas, where steam reforming converts the various light hydrocarbons in natural gas (primarily methane) into carbon monoxide and hydrogen. The resulting gases then further react in the presence of a catalyst to form methanol. Isobutylene can be produced through a variety of methods. One such method is via the isomerization of n-butane into isobutane, which then undergoes dehydrogenation to form the desired product.
Uses
MTBE is used as a fuel component in fuel for gasoline engines. It is one of a group of chemicals commonly known as oxygenates because they raise the oxygen content of gasoline.
As anti-knocking agent
MTBE has been used in gasoline at low levels, replacing tetraethyllead (TEL) as an antiknock (octane rating) additive to prevent engine knocking. Oxygenates also help gasoline burn more completely, reducing tailpipe emissions and dilute or displace gasoline components such as aromatics (e.g., benzene). Before the introduction of other oxygenates and octane enhancers, refiners chose MTBE for its blending characteristics and low cost.
Alternatives to MTBE as an anti-knock agent
Other oxygenates are available as additives for gasoline including ethanol and other ethers such as ETBE.
As a solvent
MTBE is extensively used in industry as a safer alternative to diethyl ether (which is commonly used in academic research) as the tert-butyl group prevents MTBE from forming potentially explosive peroxides. It also is used as a solvent in academic research, although it is used less commonly than diethyl ether. Although an ether, MTBE is a poor Lewis base and does not support formation of Grignard reagents. It is also unstable toward strong acids. It reacts dangerously with bromine.