Tributyl phosphate

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

The Uses of Tributyl phosphate

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

The Uses of Tributyl phosphate

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.

The Uses of Tributyl phosphate

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

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..

Fire Hazard

Special Hazards of Combustion Products: Toxic fumes of PO x

Industrial uses

1. As an antifoaming agent.
2. As a plasticizer for cellulose esters, lacquers, plastics, and vinyl resins.
3. As a complexing agent in the extraction of heavy metals, especially for the extraction of metal ions from solutions of reactor products in nuclear fuel reprocessing.
4. As an aircraft hydraulic fluid.
5. As a heat exchange medium and dielectric.
6. As a pigment-grinding agent.

Safety Profile

Poison by intraperitoneal and intravenous routes. Moderately toxic by ingestion, inhalation, and subcutaneous routes. Experimental reproductive effects. A skin, eye, and mucous membrane irritant. Combustible when exposed to heat or flame. To fight fire, use CO2, dry chemical, fog, mist. When heated to decomposition it emits toxic fumes of POx.

Carcinogenicity

TBP was not genotoxic in a variety of in vivo and in vitro assays.7 It has been suggested that the carcinogenic effects of TBP are species- and organ specific. The necrotic actions of TBP (or a metabolite) on rat urinary bladder epithelium may induce chronic repair processes that cause the normal epithelium to be transformed into its metaplastic and neoplastic forms.
TBP was not teratogenic when administered to rats and rabbits during gestation; fetotoxic effects (delayed ossification and reduced fetal body weights) occurred in rats at doses that caused severe maternal toxicity. There was no evidence of reproductive toxicity or reproductive organ pathology in twogeneration studies in rats fed TBP in the diet.

Environmental Fate

Biological. Indigenous microbes in Mississippi River water degraded tributyl phosphate to carbon dioxide. After 4 wk, 90.8% of the theoretical carbon dioxide had evolved (Saeger et al., 1979).
Chemical/Physical. Complete hydrolysis yields 1-butanol and phosphoric acid via the intermediates dibutyl phosphate and monobutyl phosphate (Thomas and Macaskie, 1996).

Purification Methods

The main contaminants in commercial samples are organic pyrophosphates, monoand dibutyl phosphates and butanol. It is purified by washing successively with 0.2M HNO3 (three times), 0.2M NaOH (three times) and water (three times), then fractionally distilled under vacuum. [Yoshida J Inorg Nucl Chem 24 1257 1962.] It has also been purified via its uranyl nitrate addition compound, obtained by saturating the crude phosphate with uranyl nitrate. This compound is crystallised three times from n-hexane by cooling to -40o, and then decomposed by washing with Na2CO3 and water. Hexane is removed by steam distillation; the water is then evaporated under reduced pressure, and the residue is distilled under reduced pressure. [Siddall & Dukes J Am Chem Soc 81 790 1959.] Alternatively, wash it with water, then with 1% NaOH or 5% Na2CO3 for several hours, then finally with water. Dry it under reduced pressure and fractionate it carefully under vacuum. It is a stable colourless oil, sparingly soluble in H2O (1mL dissolves in 165mL of H2O), but freely miscible in organic solvents. [Kuivila & Masterton J Am Chem Soc 74 4953 1952, Cox & Westheimer J Am Chem Soc 80 5441 1958, 31P NMR: Van Wazer J Am Chem Soc 78 5715 1956, Fertig et al. J Chem Soc 1488 1957, Beilstein 1 IV 1531.]

Waste Disposal

Tributyl phosphate is dissolved in a combustible solvent and is burned in a chemical incinerator equipped with an afterburner and scrubber.