21.09.2022

Phosphoric acid tributyl ester


Phosphoric acid tributyl ester, also known as tributyl phosphate or TBP, is an industrial chemical.


TBP is used mainly in industrial settings in aviation hydraulic fluids as a flame retardant, as an extraction solvent for rare earth metals from ores, in the manufacture of uranium trioxide, as a defoaming agent, as a plasticizer and in hydraulic fluid and coatings. It is also found in some paints and brake fluids.


TBP is not manufactured in Canada, but is imported into Canada.


Prior to the assessment, TBP was identified as a potential concern to human health based on its classification by international organizations as a substance which was found to cause cancer in laboratory animals, and based on a moderate potential for exposure to Canadians.


TBP may be found in indoor air and drinking water in Canada.


Canadians may be exposed to TBP during use of certain consumer products containing TBP such as paints and brake fluid.


Exposure of the general population in Canada to TBP is expected to be low.


The Government of Canada has conducted a science-based evaluation of TBP, called a screening assessment.


The Government of Canada has concluded that TBP is not harmful to human health at current levels of exposure.


Based on the conclusion of the final screening assessment, no further action will be taken on TBP.


The final screening assessment report was published on August 22, 2009.


Because Canadians' exposure to TBP is expected to be low, the Government of Canada is not currently recommending specific actions by Canadians to reduce their exposure.


As a general precaution, Canadians are reminded to carefully follow safety warnings and directions when using products containing TBP.


Tributyl phosphate


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, brake 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 is used as an anti-foaming agent in detergent solutions, and in various emulsions, paints, and adhesives. It is also found as a de-foamer 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 can be 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[edit]


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.


Tributyl phosphate Chemical Properties,Uses,Production



Tributyl phosphate (TBP) is an organophosphorus compound widely used as a solvent in nuclear fuel reprocessing for the extraction of uranium and plutonium from other radionuclides.
The major uses of tributyl phosphate (TBP) in industry are as a flame retardant component of aircraft hydraulic fluid and as a solvent for rare earth extraction and purification. Minor uses of TBP include use as a defoamer additive in cement casings for oil wells, as an anti-air entrainment additive for coatings and floor finishes, as a solvent in nuclear fuel processing, and as a carrier for fluorescent dyes.
The microbial degradation of tributyl phosphate was carried out using Klebsiella pneumoniae S3 isolated from the soil. The solubilization behavior of TBP in aqueous solutions of L64-Pluronics was studied using light and small angle neutron scattering (SANS).


UsesTributyl phosphate (TBP) is a trialkyl phosphate that is the tributyl ester of phosphoric acid. TBP is a toxic organophosphorous compound widely used in many industrial applications, including significant usage in nuclear processing. TBP is a solvent and plasticizer for cellulose esters such as nitrocellulose and cellulose acetate. 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, such as uranium and plutonium. TBP is used also in mercerizing liquids, where it improves their wetting properties. TBP 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.Preparation




Tributyl phosphate is manufactured by reaction of phosphoryl chloride with n-butanol.
A 1-liter four-necked flask is fitted with an efficient condenser, an air-tight stirrer, a short-stemmed dropping funnel and a thermometer. Calcium chloride tubes are attached to the top of dropping funnel and the reflux condenser. 137 ml (111 g) of dry n-butyl alcohol, 132.5 ml (130 g) of dry pyridine and 140 ml of dry benzene are placed in the flask, which is stirred and cooled in an ice-salt mixture until the temperature falls to – 5° C. 40.5 ml (76.5 g) of freshly redistilled (b.p. 106-107° C) phosphorus oxychloride are dropwise added from the funnel at such a rate that the temperature does not rise above 10° C. When all phosphorus oxychloride has been added the reaction mixture is gently refluxed for 2 hours and cooled to room temperature. 250 ml of water are added in order to dissolve the pyridine hydrochloride, the benzene layer is separated, washed several times with water until the washings are neutral, and dried over anhydrous sodium or magnesium sulfate. The benzene is removed by evaporation and crude tributyl phosphate is purified by distillation in a vacuum. The fraction boiling at 160-162°/15 mm or 138-140°/6 mm is collected yielding 95 g of pure tributyl phosphate.



99%TBP



Potential Exposure


The industrial application of this chemical is responsible for occupational exposure and environmental pollution. Exposure to TBP can be from ingestion, inhalation, or skin or eye contact. This exposure will most often happen from occupational use of hydraulic fluid. If TBP is released to the environment, it will bind tightly to dust particles in the air. Unbound TBP will break down in air. It will move slowly through soil because it will bind with soil particles. It may volatilize slowly from moist soil and water surfaces. It may build up in aquatic organisms. It will be broken down in water by microbes.




Description


On decomposition, TBP releases COx, toxic fumes of phosphoric acid, phosphorus oxides, and/or phosphine. TBP is incompatible with strong oxidising agents and alkalis. The major uses of TBP in industry are as a component of aircraft hydraulic fluid and as a solvent for rare earth extraction and purification. Minor uses of TBP include use as a defoamer additive in cement casings for oil wells, an anti-air entrainment additive for coatings and floor finishes, as well as a carrier for fluorescent dyes. The major uses of TBP comprise over 80% of the volume produced.



Chemical Properties



Stable, colorless liquid; odorless. Miscible with most solvents and diluents; soluble in water. Combustible.




Physical properties


Clear, colorless to pale yellow, odorless, slightly flammable, oily liquid




Uses


Plasticizer for cellulose esters, lacquers, plastics, and vinyl resins.




Uses


Tributyl phosphate is used as a plasticizer for cellulose esters, vinyl resins, and lacquers; and in making fireretardants, biocides, defoamers, and catalysts.




Uses


Tributyl phosphate is used as an antifoaming agent; plasticizer for cellulose esters, lacquers, plastic, and vinyl resins; component in hydraulic fluids for aircraft control systems.




Definition


ChEBI: A trialkyl phosphate that is the tributyl ester of phosphoric acid.




Production Methods


Prepared by the reaction of phosphorus oxychloride with butyl alcohol.



General Description


Tributyl phosphate is an organophosphorus compound, which is widely used as a flame retardant and plasticizer in a variety of industrial products.



Air & Water Reactions


Water insoluble. Reacts slowly with water under basic conditions.




Reactivity Profile


Tributyl phosphate is incompatible with strong oxidizing agents and strong bases. Attacks some forms of plastics and rubber .




Health Hazard


Tributyl phosphate is a neurotoxic compound and an irritant. The toxic effects are characteristic of organic phosphates. It inhibits cholinesterase activity and causes paralysis. Inaddition,itcancausedepressionofthecentralnervoussystem,aswellasirritationofthe skin,eyes,andrespiratorypassage.Inhalation toxicity data in the literature are inconsistent.
The oral toxicity in rats was low; the LD50 value was reported as 1189 mg/kg (NIOSH 1986).
The pure liquid instilled into rabbits’ eyes caused severe irritation but no permanent damage. The irritation effect on the skin is mild.
Tributyl phosphate exhibited teratogenic effects in rats. There is no report on its carcinogenicity..

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