SPECTRUM

Chemical Fact Sheet

Chemical Abstract Number (CAS #) 512561
CASRN 512-56-1
SynonymsTrimethylphosphate
Phosphoric acid, trimethyl ester
Molecular FormulaC3H9O4P

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use FOR CONTROLLING SPARK PLUG FOULING, SURFACE IGNITION & RUMBLE IN GASOLINE ENGINES Gasoline additive at 0.25 g/gal for controlling surface ignition and spark plug fouling; methylating agent, chemical intermediate in the production of polymethyl polyphosphates; flame retardant solvent for paints and polymers; catalyst in the preparation of polymers and resins. 481] Stabilizer; antioxidant
Apparent Color COLORLESS LIQUID
Boiling Point 197.2 DEG C AT 760 MM HG; 85 DEG C AT 26 MM HG
Melting Point ALPHA -46 DEG C (STABLE), BETA -62 DEG C
Molecular Weight 140.08
Density 1.2144 @ 20 DEG C/4 DEG C
Sensitivity Data STRONG IRRITANT TO SKIN & EYES.
Environmental Impact Trimethyl phosphate may be released to the atmosphere through evaporation of gasoline or through incompletely burned automobile exhaust fumes and it may be released to water via waste streams from manufacturing and use operations. If released to soil, trimethyl phosphate will be highly mobile in soil and will leach. Volatilization from moist soils will not be an important removal process. No biodegradation data for trimethyl phosphate in soil or water were located. If released to water, volatilization, bioconcentration in aquatic organisms and adsorption to sediment are not expected to be important fate processes for trimethyl phosphate. The hydrolysis half-life of trimethyl phosphate in aquatic systems under environmental conditions (pH 5-9) is expected to be less than or equal to 1 year and direct photolysis is not expected to be rapid. If released to the ambient atmosphere, vapor-phase trimethyl phosphate is estimated to degrade by reaction with photochemically formed hydroxyl radicals (half-life of 2.2 days). Vapor phase trimethyl phosphate may also degrade by reaction with ozone (half-life of 7.8 min). Trimethyl phosphate may be removed from the ambient atmosphere via wet deposition. The general population may be exposed to trimethyl phosphate by inhalation through evaporation of gasoline or through incompletely burned automobile exhaust fumes. Workers may also be exposed be dermal contact or inhalation during the production, storage, transport, use and waste disposal of trimethyl phosphate.
Environmental Fate TERRESTRIAL FATE: Trimethyl phosphate is not expected to volatilize from moist soils based on its low Henry's Law constant. An estimated Koc range of 3.2 to 12 suggests that trimethyl phosphate will be highly mobile in soil and will leach. No data were located to properly assess the importance of environmental biodegradation of trimethyl phosphate. AQUATIC FATE: Volatilization, bioconcentration in aquatic organisms and adsorption to sediment are not expected to be important fate processes of trimethyl phosphate in aquatic systems. Trimethyl phosphate is expected to be less volatile than water because of its low Henry's Law constant. An estimated Koc range of 3.2 to 12 suggests that trimethyl phosphate will be highly mobile in soil and sediment and will leach. An estimated BCF range of 0.24 to 0.4 suggests that bioaccumulation in aquatic organisms will not be an important fate process. The hydrolysis half-life of trimethyl phosphate in aquatic systems under environmental conditions is expected to be 1 year based on several aqueous hydrolysis studies(2-6). The absorption spectrum of trimethyl phosphate in aqueous solution shows weak absorptivity >290 nm(7) which suggests that direct photolysis is not rapid. No data were located to properly assess the importance of environmental aqueous biodegradation. ATMOSPHERIC FATE: Based on the experimentally determined vapor pressures ranging from .91-1 mm Hg at 25-26 deg C(1-3), trimethyl phosphate is expected to exist almost entirely in the vapor phase in the ambient atmosphere . The rate constant for the vapor-phase reaction of trimethyl phosphate with photochemically produced hydroxyl radicals was measured to be 7.4X10-12 cu cm/molecule-sec at 25 deg C which corresponds to an atmospheric half-life of about 2.2 days at an atmospheric concentration of 5X10 5 hydroxyl radicals per cu cm. The rate constant for the reaction of trimethyl phosphate with ozone (O3) has been experimentally determined to be <6X10-10 cu cm/molecule-sec at 25 deg C(6) which corresponds to a half-life of about 7.8 min at an average atmospheric O3 concentration of 7X10 11 molecules per cu cm(7). Based on a reported water solubility of 500,000 mg/L at 25 deg C(8), trimethyl phosphate may be removed via wet deposition.
Drinking Water Impact SURFACE WATER: Trimethyl phosphate was qualitatively detected in Japanese river water and seawater . EFFL: Trimethyl phosphate was qualitatively identified in effluents discharged into the upper reaches of the River Lee in the United Kingdom from 2 sewage treatment facilities . Trimethyl phosphate was qualitatively identified as a reaction product during the chlorination of terrestrial humic acid commonly used in the production of drinking water .

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