Tributyl phosphate

Tributyl phosphate

Tributyl phosphate

Chemical formula C12H27)3P
Names tri-n-butyl phosphate
Appearance colorless (yellowish when impure)
CAS number 126-73-8 (anhydrous)
6131-90-4 (trihydrate)
Molar mass 266.32 g/mol
Melting point 193K
(-80 °C; -112 °F)
Boiling point 562K
(289 °C; 552 °F)
Density 0.9727 g/cm3
Crystal structure FIXME orthorhombic
Solubility 1 mL /165 mL of water
ΔfH0gas -1380 kJ/mol
ΔfH0liquid -1454 kJ/mol
ΔfH0solid ?
S0gas, 1 bar ?
S0liquid, 1 bar ?
S0solid ?
Ingestion "May cause abdominal pain, vomiting. Other symptoms parallel inhalation." [1]
Inhalation "Causes irritation to the respiratory tract. Symptoms may include coughing, shortness of breath. May cause headache. May also mildly affect blood cholinesterase levels, which will affect central nervous system operation." [1]
Skin "Causes irritation to skin. Symptoms include redness, itching, and pain. May be absorbed through the skin with possible systemic effects." [1]
Eyes "Causes irritation, redness, and pain." [1]
Firefighting Data
Flash point 120C (248°F)
Extingushing Media "Water spray, dry chemical, alcohol foam, or carbon dioxide. Water or foam may cause frothing."[1]
SI units and standard conditions used unless otherwise stated.
Chemical infoboxes

Tributyl phosphate, known commonly as TBP, is an organophosphorus compound with the formula (CH3CH2CH2CH2O)3PO. This colourless, odorless liquid finds some applications as an extractant and a plasticizer. It is an ester of orthophosphoric acid with n-butanol.


Tributyl phosphate is manufactured by esterification of orthophosphoric acid with butyl alcohol. A laboratory synthesis proceeds with phosphorus oxychloride:
POCl3 + 3 C4H9OH → PO(OC4H9)3 + 3 HCl
Production is estimated at 3,000 – 5,000 tonnes worldwide.


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.

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 antifreze solutions. 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. TBP is used in some consumer products such as herbicides and water thinned paints and tinting bases.

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.


Consult MSDS In contact with concentrated nitric acid the TBP-kerosene solution forms hazardous and explosive red oil.


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