1-Methoxy-2-propanol

Chemical Properties

Propylene glycol monomethyl ether is a colorless liquid with a sweet ether-like odor and bitter taste. It is soluble in water, ether, acetone, and benzene.

Uses

1-Methoxy-2-propanol is primarily used in the manufacture of lacquers and paints, as an anti-freeze in industrial engines, a tailing agent for inks used on very high-speed presses, a coupling agent for resins and dyes in waterbased inks, and a solvent for celluloses, acrylics, dyes, inks, and stains. It is also used in cleaning products such as glass and rug cleaners, carbon and grease removers, and paint and varnish removers; and in pesticide formulations as a solvent for applications to crops and animals.

Air & Water Reactions

Highly flammable. Soluble in water. Oxidizes readily in air to form unstable peroxides that may explode spontaneously [Bretherick 1979 p.151-154, 164].

Reactivity Profile

1-Methoxy-2-propanol is a methoxy alcohol derivative. The ether being relatively unreactive. Flammable and/or toxic gases are generated by the combination of alcohols with alkali metals, nitrides, and strong reducing agents. They react with oxoacids and carboxylic acids to form esters plus water. Oxidizing agents convert them to aldehydes or ketones. Alcohols exhibit both weak acid and weak base behavior. They may initiate the polymerization of isocyanates and epoxides.

Hazard

Flammable, moderate fire risk. TLV: 100 ppm; STEL 150 ppm.

Health Hazard

VAPOR: Irritating to eyes, nose, and throat. LIQUID: Irritating to skin and eyes.

Fire Hazard

FLAMMABLE. Flashback along vapor trail may occur. Vapor may explode if ignited in an enclosed area.

Safety Profile

Moderately toxic by intravenous route. Mildly toxic by ingestion, inhalation, and skin contact. Human systemic effects by inhalation: general anesthesia, nausea. A skin and eye irritant. An experimental teratogen. Many glycol ethers have dangerous human reproductive effects. Very dangerous fire hazard when exposed to heat or flame; can react with oxidizing materials. To fight fire, use foam, CO2, dry chemical. When heated to decomposition it emits acrid smoke and irritating fumes. Used as a solvent and in solvent-sealing of cellophane. See also GLYCOL ETHERS and ETHYLENE GLYCOL MONOMETHYL ETHER.

Synthesis

1-methoxy-2-propanol is prepared by reacting propylene oxide with methanol in the presence of a racemic catalyst which comprises an asymmetric polydentate (tetradentate) ligand complexed with a metal atom, where the complex has an approximately planar geometry.

Potential Exposure

Propylene glycol monomethyl ether is used as a solvent for coatings; cellulose esters and acrylics; acrylics dyes; inks, and stains. It may also be used as a heat-transfer fluid.

Shipping

UN3092 1-Methoxy-2-propanol, Hazard Class: 3; Labels: 3-Flammable liquid.

Toxicity evaluation

Contact irritates skin, eyes and mucous membranes. Prolonged exposure to vapors may cause coughing, shortness of breath, dizziness and intoxication. Vapors heavier than air. Used as a solvent and as an antifreeze agent. The oral LD50 of rats was 6.6g/kg. The skin irritation is not obvious, but the toxic dose can be absorbed through the skin. The main manifestations of animal poisoning were inhibition and incomplete anesthesia. Half of the rats died when they were exposed to steam concentration of 40.18g/m3 for 5 ~ 6 hours. the impact of 1-methoxypropanol-2 (MEP) for the stimulation of an inflammatory response in human respiratory mucosa, we exposed 22 primary cell cultures of nasal respiratory epithelia of healthy individuals to MEP concentrations at the level of the German MAK-value (100ppm) and to the 10-fold concentration (1000ppm).

Advantages

1-Methoxy-2-propanol has been used as an antifreeze material, principally in ebullient cooling systems and in some heavy-duty diesel engines. Because an azeotrope is formed between 1-methoxy-2-propanol and water, freeze protection also is provided in the vapor phase in ebullient cooling applications. On the other hand, it is more volatile and is more readily expelled along with water vapor through the crankcase vent system. It also maintains lower metal temperatures than comparative glycolbased coolants. This was an advantage in rotary engines.

Incompatibilities

Vapor may form explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, acid chlorides, acid anhydrides, isocya- nates, aluminum, and copper. Hygroscopic (i.e., absorbs moisture from the air). May slowly form reactive peroxides during prolonged storage or on exposure to air and light.

Waste Disposal

Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed.