Methyl tert-Butyl Ether (MTBE)

About This Product

Methyl tert-butyl ether (MTBE, tert-butyl methyl ether; formula C5H12O; CAS 1634-04-4) is a clear, colourless and volatile liquid with a characteristic odour. It boils at about 55 °C, dissolves only slightly in water and mixes with most organic solvents.

The bulk of MTBE output is made from isobutylene and methanol for gasoline blending, where high octane and oxygen content aid combustion. High-purity material serves another set of buyers. As a solvent it is safer to store than diethyl ether: the carbon adjacent to the ether oxygen carries no hydrogen, so peroxide formation is far slower than in diethyl or diisopropyl ether, and the ICH Q3C guideline on residual solvents places MTBE in its lowest-concern class, which suits pharmaceutical extraction. Cracking MTBE also regenerates very pure isobutylene, the monomer for butyl rubber and polyisobutylene. Because these uses are sensitive to co-products, methanol is limited to 0.05 wt% and each related ether carries its own limit: sec-butyl methyl ether max 0.5 wt%, ethyl tert-butyl ether max 0.1 wt% and tert-amyl methyl ether max 0.2 wt%.

Applications include extraction and reaction solvent work in pharmaceutical and fine chemical plants, feedstock for high-purity isobutylene, octane and oxygenate blending in gasoline, and dissolving resins, waxes and oils.

BG Petro Chemicals supplies MTBE at 99.0 wt% minimum, specified for methanol, the related ethers, C4 hydrocarbons (max 0.05 wt%), Pt-Co colour (max 5) and sulphur (max 5 mg/L). Tert-butyl alcohol, C5 to C7 hydrocarbons and water are reported rather than limited. Packs are 150 kg drums or ISO tanks, shipped as UN 2398, Class 3, PG II. MTBE is highly flammable and irritates the skin; follow the safety data sheet when handling it.