TRIS(2-ETHYLHEXYL)PHOSPHATE

Tris(2-ethylhexyl) phosphate is an organophosphate ester produced by the esterification of phosphoric acid with 2-ethylhexanol, resulting in a high-boiling, hydrophobic, and oily liquid with strong plasticizing properties.
Tris(2-ethylhexyl) phosphates branched alkyl chains provide excellent flexibility and compatibility with many polymer systems, allowing it to effectively reduce brittleness and improve low-temperature performance in finished materials.
Tris(2-ethylhexyl) phosphate is chemically stable under normal processing conditions and exhibits relatively low volatility compared to many conventional organic solvents.

CAS Number: 78-42-2
Molecular Formula: C24H51O4P
Molecular Weight: 434.63
EINECS Number: 201-116-6

Synonyms: Tris(2-ethylhexyl) phosphate, Tris(2-ethylhexyl)phosphate, Phosphoric acid, tris(2-ethylhexyl) ester, Phosphoric acid tris(2-ethylhexyl) ester, Phosphoric Acid Tris(2-ethylhexyl) Ester, Tri(2-ethylhexyl) phosphate, Tri(ethylhexyl) phosphate, Tri(ethylhexyl) phosphate, Tris-(2-ethylhexyl)phosphate, tris-(2-ethylhexyl)phosphate, Tris(2-ethylhexy)phosphate, Tris(2-ethylhexl)phosphate, Tris(2-ethylhexyl) phosphate, 97%, Tris(2-ethylhexyl) phosphate, Selectophore(TM), >=99.0%, Tris-(2-ethylhexyl)fosfat, Tris-(2-ethylhexyl)fosfat [Czech], Tris-2(2-ethylhexyl)fosfat [Czech], Trioctyl phosphate, Trioctyl Phosphate (TOP), Phosphoric Acid Trioctyl Ester, Trioctyl' phosphate, 2-Ethyl-1-hexanol phosphate, 1-Hexanol, phosphate, 2-Ethylhexanol phosphate (3:1), TOF, Amgard TOF, NSC-407921, NSC 407921, NSC407921, CCRIS 615, HSDB 2562, TRIS(2-ETHYLHEXYL) PHOSPHATE [HSDB], EINECS 201-116-6, EC 201-116-6, UNII-BQC0BKB72S, CHEBI:181994, CHEMBL1562290, BRN 1715839, RefChem:191857, MFCD00009491, DTXSID0021414, DTXCID801414, SCHEMBL35485, MLS002415769, AKOS015843194, AI3-07852, BQC0BKB72S, HMS3039O17, Tox21_201369, Tox21_300321, CS-W009670, HY-W008954, NCGC00091821-01, NCGC00091821-02, NCGC00091821-03, NCGC00254160-01, NCGC00258921-01, SMR001370923, SY048150, NS00002729, P1022, F544773, Q2454094, WLN: 4Y2&1OPO&O1Y4&2&O1Y4&2, PHOSPHORIC ACID TRIS(2-ETHYLHEXYL) ESTER;PHOSPHORIC ACID TRIOCTYL ESTER;TRIS(2-ETHYLHEXYL) PHOSPHATE;TRI(2-ETHYLHEXYL)PHOSPHATE;TRIOCTYL PHOSPHATE;'TRIOCTYL' PHOSPHATE;1-Hexanol, 2-Ethyl-, phosphate;2-ethyl-1-hexanophosphate

Tris(2-ethylhexyl) phosphate is widely used as a plasticizer and functional additive in plastics such as polyvinyl chloride, synthetic rubbers, and cellulose-based polymers, where it enhances elasticity, durability, and mechanical stability.
Due to the presence of the phosphate group, Tris(2-ethylhexyl) phosphate also contributes flame-retardant and anti-wear characteristics, which makes it suitable for use in hydraulic fluids, lubricants, and metalworking fluids.
In coatings, adhesives, and sealants, it improves flow behavior, film formation, and long-term resistance to mechanical stress.

Tris(2-ethylhexyl) phosphate, a clear, viscous liquid, is used as a component of vinyl stabilizers, grease additives, and flame-proofing compositions; however, it is used primarily as a plasticizer for vinyl plastic and synthetic rubber compounds.
Tris(2-ethylhexyl) phosphate has been employed as a specialty flameretardant plasticizer for vinyl compositions where low temperature flexibility is critical, eg, in military tarpaulins. It can be included in blends with general purpose plasticizers such as phthalate esters to improve low temperature flexibility.

Tris(2-ethylhexyl) phosphate is an organic chemical compound in the organophosphate group. 
Tris(2-ethylhexyl) phosphate is a triakylphosphate.
Tris(2-ethylhexyl) phosphate is easily separated from polymers if present as a plasticizer, it is often found in house dust.

Tris(2-ethylhexyl) phosphate is a colourless, viscous liquid with a faint, piercing smell. It has a viscosity of 15 mPas at 20 °C.
Tris(2-ethylhexyl) phosphate is valued in industrial formulations because it maintains performance over a wide temperature range and does not easily crystallize under cold conditions.
Its molecular structure allows it to remain evenly dispersed within polymer matrices without significant migration to the surface during long-term use.

This stability contributes to extended service life and consistent mechanical properties in finished products.
In fluid applications, Tris(2-ethylhexyl) phosphate acts as an effective anti-wear and load-bearing additive by forming protective boundary films on metal surfaces.
It helps reduce friction and component wear in hydraulic systems and machinery operating under high pressure or elevated temperatures.

These properties make it particularly useful in fire-resistant hydraulic fluids and specialty industrial lubricants.
From a chemical behavior perspective, Tris(2-ethylhexyl) phosphate shows low water solubility and strong affinity for organic phases, which influences its environmental distribution.

Tris(2-ethylhexyl) phosphate can persist in soils and sediments if released, although it generally exhibits low volatility into the atmosphere.
Careful handling and controlled disposal are therefore important to minimize environmental impact and occupational exposure.

Melting point: −70 °C
Boiling point: 215 °C at 4 mm Hg (lit.)
Density: 0.92 g/mL at 20 °C (lit.)
Vapor pressure: 2.1 mm Hg at 20 °C
Refractive index: n²⁰/D 1.444 (lit.)
Flash point: >230 °F
Storage temp.: Store below +30 °C
Solubility: <0.001 g/L
Form: Liquid
Specific gravity: 0.93
Color: Colourless
pH: 7 (H₂O, 20 °C)
Water solubility: <0.1 g/100 mL at 18 °C
BRN: 1715839

Tris(2-ethylhexyl) phosphate is also used as a processing aid because it improves melt flow and reduces internal friction during polymer compounding and shaping operations.
This effect allows manufacturers to process materials at lower temperatures or with reduced mechanical stress, which can help prevent degradation of heat-sensitive polymers.
As a result, product quality, surface finish, and dimensional stability can be significantly improved.

In electrical and electronic materials, Tris(2-ethylhexyl) phosphate contributes to enhanced fire safety while maintaining flexibility and insulation performance.
Its low electrical conductivity and compatibility with polymeric insulating materials make it suitable for cable coatings, wire jacketing, and molded components.
The balance between flame resistance and mechanical softness is a key reason for its selection in such applications.

From a health and safety perspective, prolonged or repeated exposure to Tris(2-ethylhexyl) phosphate may cause irritation to the skin, eyes, or respiratory system.
Although it is not classified as a highly toxic organophosphate, chronic exposure at elevated levels may still pose potential risks that require industrial hygiene controls.
Proper ventilation, protective equipment, and adherence to handling guidelines are therefore important in occupational settings.

Tris(2-ethylhexyl) phosphate is incompatible with oxidizing materials. 
Tris(2-ethylhexyl) phosphate may soften or deteriorate certain plastics and elastomers. 
Tris(2-ethylhexyl) phosphate is incompatible with cellulose acetate and cellulose acetate butyrate.

Tris(2-ethylhexyl) phosphate, in an equal volume of diethyl ether, is shaken with aqueous 5% HCl, and the organic phase is filtered to remove traces of pyridine (used as a solvent during manufacture) as its hydrochloride. 
This layer is shaken with aqueous Na2CO3, then water, and the ether is distilled off at room temperature. 

The ester is then filtered, dried for 12hours at 100o/15mm, and again filtered, then shaken intermittently for 2days with activated alumina (100g/L). 
Tris(2-ethylhexyl) phosphate is decanted through a fine sintered-glass disc (with exclusion of moisture), and distilled under vacuum.

Uses:
Tris(2-ethylhexyl) Phosphate is used as a phosphorous flame retardant. Used as a plasticizer in the preparation of a new potentiometric membrane sensor.
Due to its properties (including that it is a mild biocide), tris(2-ethylhexyl)phosphate is used in a variety of applications: as a plasticizer in polymers (PVC, PU, NBR and others) giving good cold flexibility and flame retarding properties, as a carrier for pigments and dyes used in colouring polymers, as a component in cutting fluid, as a component in release agents, used in the metal casting industry, as a solvent in hydrogen peroxide synthesis.

Tris(2-ethylhexyl) phosphate is widely used as a plasticizer in polymers such as polyvinyl chloride, cellulose resins, and synthetic rubbers to improve flexibility, softness, and low-temperature performance.
Tris(2-ethylhexyl) phosphate enhances durability and reduces brittleness in finished plastic products that are exposed to mechanical stress or temperature fluctuations.
These properties make it suitable for use in flexible cables, films, sheets, and molded plastic components.

In industrial fluids, Tris(2-ethylhexyl) phosphate is applied as a flame-retardant, anti-wear, and extreme-pressure additive in hydraulic fluids, lubricants, and metalworking fluids.
It helps reduce friction and wear by forming protective films on metal surfaces under high load and high temperature conditions.
Its fire-resistant behavior makes it especially valuable in hydraulic systems used in mining, aviation, and heavy machinery.

Tris(2-ethylhexyl) phosphate is also used in coatings, adhesives, sealants, and inks to improve flow properties, film formation, and long-term mechanical stability.
It acts as a carrier or compatibility agent for hydrophobic additives, pigments, and functional chemicals in complex formulations.
In electrical and electronic applications, it is used in plasticized insulating materials where flexibility, flame resistance, and thermal stability are required simultaneously.

Tris(2-ethylhexyl) phosphate is used in polymer processing as a compounding aid to improve melt flow and processing efficiency during extrusion, calendaring, and injection molding operations.
It allows manufacturers to achieve uniform dispersion of fillers and additives while reducing processing temperatures and mechanical shear.
This contributes to improved surface quality and consistent physical properties in the final polymer products.

In specialty industrial applications, Tris(2-ethylhexyl) phosphate is incorporated into fire-resistant hydraulic fluids used in environments where ignition risk must be minimized.
It provides a balance between lubrication performance and flame retardancy in systems operating under high pressure.
Such fluids are commonly applied in steel plants, power generation facilities, and heavy-duty industrial equipment.

Tris(2-ethylhexyl) phosphate is also utilized in the formulation of elastomers and rubber compounds to enhance flexibility and resistance to aging.
It helps maintain elasticity over extended service periods and under repeated mechanical stress.
These characteristics support its use in hoses, seals, gaskets, and vibration-damping materials.

Tris(2-ethylhexyl) phosphate is used in the production of flexible foams and specialty plastics where long-term softness and resistance to compression set are required.
It helps maintain structural integrity while allowing repeated deformation without cracking or loss of performance.
These properties are beneficial in cushioning materials, protective components, and vibration-absorbing parts.

In ink and pigment formulations, Tris(2-ethylhexyl) phosphate functions as a dispersing and compatibility agent that improves uniformity and stability.
It assists in keeping pigments evenly distributed, preventing settling and improving print quality or coating appearance.
This role supports its use in industrial printing inks and protective coatings.

Tris(2-ethylhexyl) phosphate is also applied in adhesive and sealant systems to enhance flexibility and adhesion to various substrates.
It improves resistance to thermal cycling and mechanical movement at bonded interfaces.
Such performance makes it suitable for construction, automotive, and industrial assembly applications.

Safety Profile:
When heated above its flash point of 170 °C, Tris(2-ethylhexyl) phosphate can release vapours capable of forming explosive mixtures with air.
Tris(2-ethylhexyl) phosphate has a particularly high bioaccumulation factor amongst organophosphate flame retardants.
Tris(2-ethylhexyl) phosphate may cause irritation to the skin and eyes upon direct contact, especially with prolonged or repeated exposure.

Contact with liquid material can lead to redness, dryness, or discomfort, and splashes may cause temporary eye irritation.
Proper use of protective gloves and eye protection is recommended during handling.
Inhalation of mists or aerosols containing Tris(2-ethylhexyl) phosphate can irritate the respiratory tract.

Repeated or long-term inhalation exposure in occupational settings may contribute to respiratory discomfort or nonspecific systemic effects.
Adequate ventilation and control of airborne concentrations are important to reduce inhalation risk.

From an environmental perspective, Tris(2-ethylhexyl) phosphate is poorly soluble in water and can persist in soils and sediments if released.
Tris(2-ethylhexyl) phosphate may be harmful to aquatic organisms at elevated concentrations due to its tendency to accumulate in organic phases.
Spills should be contained and disposed of properly to prevent environmental contamination and long-term ecological effects.