Tributyl phosphate
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| Identifiers | |
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3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.004.365 |
| KEGG | |
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C12H27O4P | |
| Molar mass | 266.318 g·mol−1 |
| Appearance | Colorless to pale-yellow liquid[1] |
| Density | 0.9727 g/mL |
| Melting point | −80 °C (−112 °F; 193 K) |
| Boiling point | 289 °C (552 °F; 562 K) |
| 1 mL/165 mL water | |
| Vapor pressure | 0.004 mmHg (25°C)[1] |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Flash point | 146.1 °C (295.0 °F; 419.2 K) |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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1189 mg/kg (mouse, oral) 3000 mg/kg (rat, oral)[2] |
LC50 (median concentration)
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227 ppm (cat, 4-5 hr) 123 ppm (rat, 6 hr) 117 ppm (rat) 2529 ppm (rat, 1 hr)[2] |
LCLo (lowest published)
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2214 ppm (cat, 5 hr)[2] |
| NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 5 mg/m3[1] |
REL (Recommended)
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TWA 0.2 ppm (2.5 mg/m3)[1] |
IDLH (Immediate danger)
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30 ppm[1] |
| Safety data sheet (SDS) | External MSDS |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Tributyl phosphate, known commonly as TBP, is an organophosphorus compound with the chemical formula (CH3CH2CH2CH2O)3PO. This colourless, odorless liquid finds some applications as an extractant and a plasticizer. It is an ester of phosphoric acid with n-butanol.
Production
Tributyl phosphate is manufactured by esterification of phosphoric acid with n-butanol. A laboratory synthesis proceeds with phosphoryl chloride:[3]
- POCl3 + 3 C4H9OH → PO(OC4H9)3 + 3 HCl>
Production is estimated at 3,000–5,000 tonnes worldwide.[4]
Use
TBP is a solvent and plasticizer for cellulose esters such as nitrocellulose and cellulose acetate. It forms stable hydrophobic complexes with some metals; these complexes are soluble in organic solvents as well as supercritical CO2. The major uses of TBP in industry are as a component of aircraft hydraulic fluid and as a solvent for extraction and purification of rare earth metals from their ores.[4]
TBP finds its use as a solvent in inks, synthetic resins, gums, adhesives (namely for veneer plywood) and herbicide and fungicide concentrates.
As it has no odour, it finds use as anti-foaming agent in detergent solutions, and in various emulsions, paints, and adhesives. It is also found as a defoamer in ethylene glycol-borax antifreeze solutions.[citation needed] In oil-based lubricants addition of TBP increases the oil film strength. It is used also in mercerizing liquids, where it improves their wetting properties. It is also used as a heat exchange medium.[5] TBP is used in some consumer products such as herbicides and water thinned paints and tinting bases.[6]
Nuclear chemistry
A 15–40% (usually about 30%) solution of tributyl phosphate in kerosene or dodecane is used in the liquid–liquid extraction (solvent extraction) of uranium, plutonium, and thorium from spent uranium nuclear fuel rods dissolved in nitric acid, as part of a nuclear reprocessing process known as PUREX.
The shipment of 20 tons of tributyl phosphate to North Korea from China in 2002, coinciding with the resumption of activity at Yongbyon Nuclear Scientific Research Center, was seen by the United States and the International Atomic Energy Agency as cause for concern; that amount was considered sufficient to extract enough material for perhaps three to five potential nuclear weapons.[7]
Hazards
In contact with concentrated nitric acid the TBP-kerosene solution forms hazardous and explosive red oil.
References
- ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0625". National Institute for Occupational Safety and Health (NIOSH).
- ^ a b c "Tributyl phosphate". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ G. R. Dutton and C. R. Noller (1943). "n-Butyl phosphate". Organic Syntheses; Collected Volumes, vol. 2, p. 109.
- ^ a b "Tributyl Phosphate | SIDS Initial Assessment Profile" (PDF). Japan Chemical Industry Ecology-Toxicology & Information Center.
- ^ "Tributyl Phosphate Product Information". Great Vista Chemicals.
- ^ "Tributyl Phosphate". Scorecard.
- ^ "Yongbyon - North Korean Special Weapons Facilities". GlobalSecurity.org.