tert-Butyl methyl ether C5H12O CAS 1634-04-4

CAS No.: 1634-04-4
Synonyms: tert-Butyl methyl ether, 2-Methoxy-2-methylpropane
Molecular Formula:
C5H12​O
Molecular Weight: 88.15
EINECS: 216-653-1
UN Number: 2398

1. Basic Description
Methyl tert-butyl ether (MTBE) is a volatile, colorless transparent liquid with a mild terpene-like odor. It belongs to the aliphatic ether family. It is synthesized by acid-catalyzed addition reaction of methanol and isobutene. It is miscible with most organic solvents such as ethanol, acetone and hydrocarbons, and slightly soluble in water. MTBE is highly flammable and widely produced in the petrochemical industry worldwide.

2. Typical Physical & Chemical Properties

Item Specification
Appearance Colorless clear liquid
Density (20°C) 0.740 g/mL
Boiling Point 55.2 °C
Melting Point -109 °C
Flash Point (closed cup) -28 °C
Research Octane Number (RON) 118
Water Solubility ~4.2 g/100 mL at 20°C
Vapor Pressure (25°C) 32.59 kPa

3. Main Applications
Gasoline oxygenate & octane booster (major use)
MTBE has excellent anti-knock performance. It is blended into gasoline to raise octane value, replace leaded additives, reduce carbon monoxide and hydrocarbon exhaust emissions, and adjust fuel Reid vapor pressure. It is the most mainstream application of MTBE.
Petrochemical intermediate
MTBE can be cracked to produce high-purity isobutene, which is an important raw material for manufacturing butyl rubber, polyisobutene and other fine chemicals.
Industrial & laboratory solvent
It is a low-toxicity ether solvent, widely used in extraction, pharmaceutical synthesis, organic reaction, sample pretreatment, replacing diethyl ether in many cases for safer operation.

4. Safety & Handling Notes
Hazard Class: Highly flammable liquid. Vapors may form explosive mixtures with air. Keep away from open flame, static electricity and heat sources.
Health hazard: Inhalation of high concentration vapor causes dizziness, nausea and respiratory irritation. Skin or eye contact leads to irritation.
Environmental note: MTBE has relatively high mobility in groundwater. Leakage should be strictly prevented.
Storage: Store in sealed containers in cool, well-ventilated warehouse, separated from oxidants.

5. Quality Specification (Industrial Grade, for reference)
Purity: ≥99.0%
Water content: ≤0.05%
Methanol: ≤0.5%
tert-Butyl alcohol: ≤0.5%