MTBE (Methyl Tertiary Butyl Ether)


CH3 - O - C (CH3)3


Methyl Tertiary Butyl Ether (MTBE) is a colorless liquid with a characteristic mild odor. Its principal characteristics are miscibility with gasoline, low blending vapor pressure and distillation properties. MTBE is slightly soluble in water without phase separation problems. Compared to other oxygenated fuels, it has lower blending density, lower blending vapor pressure and no corrosion problems.


Specific gravity°C at 20°C/20°C0.74
IBP°C at 1.0 atm50.5 min
FBP°C at 1.0 atm74.5 max
CAS number1634-04-4
IUPAC name2-Methoxy-2-methylpropane


ParameterUnitQuantityTest Method
Puritywt %98 minASTM D-5441
C4-hydrocarbonswt %0.5 maxASTM D-5441
C5-hydrocarbonswt %1 maxASTM D-5441
Methanolwt %0.7 maxASTM D-5441
Ter-butyl alcoholwt %0.6 maxASTM D-5441
Di-isobutenewt %0.6 maxASTM D-5441
Waterppm500 maxASTM D-1364

ASTM : American Society for Testing and Materials

Hazards and safety

MTBE’s toxicological effect is largely similar to that of lead-free gasoline. It has no special toxic effects, symptoms or hygienic requirements.

Flash point°C-26
Flammable limitsvol % in air1.6-84
Ignition temperature°C430
UN or ID No.2398


MTBE is used mainly as a high octane gasoline blending component. It replaces lead compounds and provides good anti-knock characteristics.

Storage and handling

MTBE can be shipped or stored in conventional fuel tanks. Nitrogen purging is strongly recommended in case of loading vessels in hot weather. Acid or iron rust contamination should be avoided. MTBE does not form peroxide compounds on long period storage.

MTBE is shipped in fuel tanks (similar to those used for gasoline). Each shipping tank or container must bear the label “Flammable Liquid”.