Methyl tert-Butyl Ether (MTBE)

About This Product

Methyl tert-butyl ether, MTBE, has the formula C5H12O and CAS number 1634-04-4. It is a clear, colourless, volatile liquid with a characteristic odour, boiling at about 55 °C, slightly soluble in water and miscible with most organic solvents. Most MTBE is made from isobutylene and methanol and blended into gasoline, where its high octane and oxygen content improve combustion. The high-purity grade is a different product with different buyers. As a solvent its advantage over diethyl ether is safety in storage: the tert-butyl group has no hydrogen on the carbon next to the oxygen, so MTBE forms peroxides far more slowly than diethyl or diisopropyl ether, and it is in the lowest-concern class of the ICH Q3C guideline for residual solvents, which suits pharmaceutical extraction. It is also cracked back to isobutylene of very high purity for butyl rubber and polyisobutylene. For those uses the co-products matter, so methanol is limited to 0.05 percent and the related ethers sec-butyl methyl ether, ethyl tert-butyl ether and tert-amyl methyl ether are individually specified. It is used as an extraction and reaction solvent in pharmaceutical and fine chemical manufacture, as feedstock for high-purity isobutylene, as a gasoline octane and oxygenate component, and as a solvent for resins, waxes and oils. Bio Green Chem supplies MTBE at 99 percent minimum to specification on methanol, related ethers, C4 hydrocarbons, colour and sulphur, with tert-butyl alcohol, C5 to C7 hydrocarbons and water reported, in 150 kg drums or ISO tanks. It is highly flammable and a skin irritant; handle to the safety data sheet.