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Phenyl butyl phosphate is an organophosphorus compound that functions as both a flame-retardant and plasticizer, widely used in polymers, resins, textiles, coatings, and rubber materials.
Phenyl butyl phosphate's high thermal stability, hydrolysis resistance, and ability to promote char formation during combustion make it an effective additive for enhancing fire safety while preserving mechanical performance.
In addition to flame-retardant and plasticizing roles, Phenyl butyl phosphate also serves as an anti-wear additive in lubricants and hydraulic fluids, and as an intermediate in the synthesis of other organophosphorus compounds.
CAS Number: 56803-37-3
EC Number: 260-391-0
Molecular Formula: C₁₀H₁₅O₄P
Molecular Weight: ~230.20 g/mol
Synonyms: arylphosphates, tert-Butylphenyl diphenyl phosphate, T-BUTYLPHENYL DIPHENYL PHOSPHATE, phosphoric acid (1,1-dimethylethyl)phenyl diphenyl ester, Tetrabutylphenyl diphenylphosphate, BPDP, PARA-TERT-BUTYLPHENYLDIPHENYLPHOSPHATE, tert.-Butylphenyldiphenylphosphat
Phenyl butyl phosphate is an organophosphorus compound that consists of a phosphate ester group bonded to a phenyl ring and a butyl chain.
Phenyl butyl phosphate typically appears as a colorless to pale yellow liquid with low volatility and is only slightly soluble in water but readily miscible with most organic solvents.
Like other phosphate esters, Phenyl butyl phosphate exhibits flame-retardant, plasticizing, and anti-wear properties, which makes it valuable in industrial applications.
Phenyl butyl phosphate is commonly used as a plasticizer in polymers and resins, as an additive in lubricants and hydraulic fluids, and as a flame-retardant component in coatings and plastics due to its ability to reduce flammability by promoting char formation and suppressing ignition.
In chemical research, Phenyl butyl phosphate may also serve as an intermediate in the synthesis of other organophosphate derivatives.
Phenyl butyl phosphate should be handled with care, as phosphate esters can hydrolyze under acidic or alkaline conditions, potentially releasing corrosive or toxic by-products.
Phenyl butyl phosphate is an organophosphorus compound that has been used as a flame retardant additive in plastics and textiles.
Phenyl butyl phosphate has been detected at median concentrations of 0.2 ng/g in human urine, suggesting that it may be present in the general population.
A recent transcriptomic study revealed that Phenyl butyl phosphate inhibits the transcriptional activity of polymerase chain reaction (PCR) by binding to the DNA polymerase enzyme.
Phenyl butyl phosphate also binds to the liver microsomes of rats, demonstrating its toxicological properties.
Phenyl butyl phosphate is structurally related to other phosphates such as carbon disulphide, which has been studied extensively for its carcinogenic effects on humans and animals.
Phenyl butyl phosphate is a highly effective flame retardant plasticizer, with good compatibility with PVC and other alloys such as PPO, PC/ABS.
When Phenyl butyl phosphate is considered as a conventional plasticizer, it can balance the flame retardancy and plasticizing efficiency of the system.
Phenyl butyl phosphate's high thermal stability allows it to be used as a flame retardant for engineering plastics and also improves the melting performance of plastics.
Phenyl butyl phosphate is a new generation of halogen-free organophosphorus flame retardants, which have excellent thermal stability and excellent hydrolysis resistance.
Phenyl butyl phosphate's high thermal stability allows it to be used as a flame retardant for engineering plastics, as well as to improve the melting properties of plastics.
Phenyl butyl phosphate has superior performance over TPP.
Phenyl butyl phosphate is a liquid, which has better durability and hydrolytic stability in resin, and is not easy to produce surface stress cracking, and is widely used in flame retardant PVC, cellulose resin, synthetic rubber, resin, epoxy resin, polyester fiber, etc.
Phenyl butyl phosphate is an organophosphorus ester that belongs to the class of phosphate esters, compounds widely recognized for their flame-retardant and plasticizing properties.
Structurally, Phenyl butyl phosphate contains a phosphate group (–OPO₃) bonded to a phenyl ring and a butyl chain, giving it both aromatic stability and aliphatic flexibility.
Phenyl butyl phosphate is generally encountered as a colorless to light yellow, oily liquid, with low volatility, a relatively high boiling point, and a tendency to hydrolyze slowly under acidic or alkaline conditions.
Phenyl butyl phosphate is sparingly soluble in water but demonstrates good solubility in most organic solvents such as alcohols, ketones, and hydrocarbons, making it highly compatible with industrial formulations.
From an industrial perspective, Phenyl butyl phosphate is widely used as a plasticizer in polymer production, where it improves flexibility, durability, and processability of plastics and resins.
Phenyl butyl phosphate's flame-retardant capability makes it valuable in coatings, plastics, and textiles, as the phosphate group helps suppress ignition and promotes the formation of char, thereby reducing flammability.
In addition, Phenyl butyl phosphate finds use in lubricants, greases, and hydraulic fluids, where it provides anti-wear, extreme-pressure resistance, and thermal stability under demanding mechanical conditions.
In chemical research and synthesis, Phenyl butyl phosphate serves as an intermediate in the preparation of other organophosphate derivatives and can be used as a reagent in reactions involving phosphorylation.
Safety considerations are important when handling Phenyl butyl phosphate, since organophosphates may produce toxic by-products upon hydrolysis or thermal decomposition, including phosphoric acid derivatives.
For this reason, Phenyl butyl phosphate should be stored in airtight containers, in a cool, dry, and well-ventilated environment, away from strong acids, bases, or oxidizing agents.
Overall, Phenyl butyl phosphate is a versatile specialty chemical, valued for its ability to combine plasticizing, flame-retardant, and lubrication-enhancing properties, which makes it useful across plastics, coatings, textiles, lubricants, and advanced materials industries.
Phenyl butyl phosphate's balanced chemical structure provides both stability and reactivity, ensuring a wide range of industrial applications.
Market Overview of Phenyl Butyl Phosphate:
The market for Phenyl butyl phosphate is shaped by its demand as a plasticizer, flame retardant, and lubricant additive across various industrial sectors.
Growth in the polymer, coatings, and textile industries has been a significant driver, as manufacturers increasingly seek additives that can improve material flexibility and processability while also enhancing fire safety.
Phenyl butyl phosphate's role in flame-retardant coatings and building materials has gained attention due to stricter fire safety regulations and the rising need for safer construction and consumer products.
In the lubricants and hydraulic fluids market, Phenyl butyl phosphate is valued as an anti-wear and extreme-pressure additive, supporting high-performance mechanical systems in automotive, aerospace, and industrial machinery.
Geographically, Asia-Pacific is expected to remain the largest consumer, driven by rapid industrialization, strong polymer production, and infrastructure growth in countries such as China and India.
Meanwhile, North America and Europe show stable demand, supported by advanced automotive, aerospace, and specialty chemical sectors, though environmental regulations on certain organophosphates may influence usage patterns.
Overall, the market outlook is moderately positive, with demand driven by fire safety compliance, performance-enhancing lubricants, and the need for multifunctional additives in modern materials and industrial processes.
Uses of Phenyl Butyl Phosphate:
Phenyl butyl phosphate is primarily used as a plasticizer and flame retardant in polymer and resin systems, where it improves flexibility, durability, and resistance to ignition.
In the plastics and coatings industry, Phenyl butyl phosphate is incorporated into formulations to enhance processability and to suppress flammability by promoting char formation during combustion.
Phenyl butyl phosphate is also applied in textiles and surface treatments, where its flame-retardant properties provide added safety in fabrics and coatings.
In the lubricant and hydraulic fluid sector, Phenyl butyl phosphate functions as an anti-wear and extreme-pressure additive, improving the thermal stability and performance of oils, greases, and specialty fluids used in high-stress mechanical systems.
Additionally, in chemical research and manufacturing, Phenyl butyl phosphate serves as an intermediate in the synthesis of other organophosphorus compounds and can be used as a reagent in phosphorylation reactions.
Phenyl butyl phosphate's combination of plasticizing, flame-retardant, and lubricating properties makes Phenyl butyl phosphate a valuable compound across a range of industrial, engineering, and chemical applications.
Phenyl butyl phosphate, as an important chemical substance, has a wide range of applications in many fields.
Phenyl butyl phosphate can also be used to prepare other chemicals as raw materials or intermediates for synthesizing other organophosphorus compounds.
In summary, Phenyl butyl phosphate, as an important organophosphorus flame retardant, has a wide range of applications in many fields such as plastics, rubber, coatings, adhesives and textiles.
Phenyl butyl phosphate's excellent thermal stability and hydrolysis resistance make it an ideal choice for improving the flame retardancy of materials.
Applications of Phenyl Butyl Phosphate:
Phenyl butyl phosphate finds application across multiple industries due to its dual role as a plasticizer and a flame-retardant additive.
In the polymer and resin industry, Phenyl butyl phosphate is used to improve flexibility, processability, and mechanical strength of plastics, films, and coatings while simultaneously reducing their flammability.
Phenyl butyl phosphate's ability to promote char formation during combustion makes it particularly useful in fire-resistant coatings, textiles, and building materials.
In the lubricants and hydraulic fluids sector, Phenyl butyl phosphate functions as an anti-wear and extreme-pressure additive, enhancing thermal stability, oxidation resistance, and lubrication properties in high-performance oils, greases, and specialty fluids.
Beyond industrial formulations, Phenyl butyl phosphate also serves as a chemical intermediate in the synthesis of other phosphate esters and organophosphorus derivatives, and it can be employed as a reagent in phosphorylation reactions within chemical research.
These diverse applications highlight Phenyl butyl phosphate's importance as a multifunctional specialty chemical that combines plasticizing, flame-retardant, and lubrication-enhancing properties in one molecule.
Main Applications:
Phenyl butyl phosphate is an organophosphorus flame retardant with excellent thermal stability and excellent hydrolysis resistance.
Phenyl butyl phosphate's main uses include:
Flame retardant:
Phenyl butyl phosphate is widely used in various plastics, resins and rubber materials, such as PVC, cellulose-based resins, synthetic rubbers, phenolic resins, epoxy resins, etc., to improve the flame retardancy of these materials.
Compared with other flame retardants, Phenyl butyl phosphate has better durability and hydrolytic stability, and is less likely to produce surface stress cracking.
Plasticizer:
In some applications, Phenyl butyl phosphate is also used as a plasticizer, which can improve the flexibility and processing performance of materials.
Specific application areas:
Engineering plastics:
As a flame retardant for engineering plastics, Phenyl butyl phosphate can significantly improve the flame retardant rating of the plastic while maintaining the mechanical and processing properties of the material.
Rubber Industry:
As a flame retardant or plasticizer in rubber products, Phenyl butyl phosphate can improve the flame retardant performance and flexibility of rubber, which is widely used in tires, seals and other rubber products.
Coatings and Adhesives:
In some coatings and adhesives, Phenyl butyl phosphate is used as an additive, which can improve the flame retardant properties and durability of the products.
Textile Industry:
In textile treatment, Phenyl butyl phosphate can be used to improve the flame retardant properties of textiles and protect people from the threat of fire.
Benefits of Phenyl Butyl Phosphate:
Phenyl butyl phosphate offers several important benefits that make it a valuable multifunctional additive in industrial and chemical applications.
Phenyl butyl phosphate's primary advantage lies in its ability to act as both a plasticizer and a flame retardant, improving the flexibility, durability, and processability of polymers while simultaneously lowering their flammability and enhancing fire safety.
In coatings, textiles, and building materials, this dual functionality reduces the need for multiple additives, lowering costs and simplifying formulations.
Another significant benefit is Phenyl butyl phosphate's role as an anti-wear and extreme-pressure agent in lubricants and hydraulic fluids, where it improves thermal stability, oxidation resistance, and mechanical performance under high-stress operating conditions.
From a chemical standpoint, Phenyl butyl phosphate provides versatility as an intermediate and reagent in the synthesis of other organophosphorus compounds, supporting innovation in specialty chemicals.
Additionally, Phenyl butyl phosphate's low volatility, good solvent compatibility, and resistance to thermal degradation make it reliable in demanding industrial environments.
Together, these benefits highlight Phenyl butyl phosphate as a cost-effective, multifunctional, and performance-enhancing compound across polymers, coatings, lubricants, and chemical synthesis.
Production of Phenyl Butyl Phosphate:
Phenyl butyl phosphate is typically produced by the esterification of phosphoric acid derivatives with phenol and butanol under controlled conditions.
The process generally begins with the preparation of a reactive phosphorus intermediate, such as phosphorus oxychloride (POCl₃) or phosphoric acid, which is then reacted sequentially or simultaneously with phenol and butanol in the presence of a catalyst (commonly strong acids or suitable metal-based catalysts).
The reaction proceeds through substitution at the phosphorus atom, forming the phosphate ester bond.
Careful control of reaction conditions—including temperature, pH, and molar ratios—is necessary to ensure selective formation of Phenyl butyl phosphate and to minimize by-products such as di- or tri-substituted phosphates.
Once the esterification is complete, the crude product undergoes neutralization, washing, and purification steps to remove unreacted raw materials, catalysts, and side products.
The final compound is obtained as a colorless to pale yellow liquid with low volatility and high thermal stability, suitable for use in plasticizers, flame retardants, and lubricants.
On an industrial scale, production is often carried out in continuous stirred-tank reactors or batch reactors, with purification involving distillation or solvent extraction to achieve the required chemical purity and performance specifications.
Synthesis of Phenyl Butyl Phosphate:
Phenyl butyl phosphate is synthesized through esterification of phosphoric acid or its derivatives with phenol and butanol, leading to the formation of a mixed aryl–alkyl phosphate ester. The process generally involves the following pathways:
Reaction with Phosphorus Oxychloride (POCl₃):
One of the most common industrial methods.
Phenol and butanol are reacted with phosphorus oxychloride in the presence of an acid catalyst (e.g., pyridine or tertiary amines may be used as HCl scavengers).
The reaction proceeds via nucleophilic substitution, where hydroxyl groups from phenol and butanol replace chlorine atoms on the phosphorus center.
The by-product is hydrogen chloride gas, which must be neutralized or removed.
General Reaction:
POCl3+C6H5OH+C4H9OH⟶(C6H5O)(C4H9O)PO2+2HCl
Reaction with Phosphoric Acid or Polyphosphoric Acid:
An alternative method uses phosphoric acid (H₃PO₄) as the phosphorus source.
Phenol and butanol are esterified with phosphoric acid under dehydrating conditions (often using heat and acid catalysts).
Water formed during the esterification must be continuously removed (e.g., azeotropic distillation) to drive the reaction forward.
General Reaction:
H3PO4+C6H5OH+C4H9OH⟶(C6H5O)(C4H9O)PO2H+2H2O
Catalytic and Controlled Synthesis:
Industrial synthesis requires strict control of molar ratios of phenol and butanol to phosphorus reagent in order to favor the mono-substituted phosphate ester (Phenyl butyl phosphate) rather than triaryl or trialkyl phosphate by-products.
Catalysts such as sulfuric acid, p-toluenesulfonic acid, or metal chlorides may be used to accelerate esterification.
Purification:
After the reaction, the crude mixture is purified by neutralization, washing, and distillation to remove unreacted phenol, butanol, or excess acid/chloride reagents.
The final product is an oily, colorless to pale yellow liquid with low volatility and high thermal stability.
History of Phenyl Butyl Phosphate:
The history of Phenyl butyl phosphate is closely linked to the development of organophosphorus chemistry in the early 20th century, when chemists began exploring phosphate esters as versatile compounds with flame-retardant, plasticizing, and lubricating properties.
The general class of aryl–alkyl phosphate esters, to which Phenyl butyl phosphate belongs, emerged as industrially significant during the 1930s and 1940s, at a time when safer and more effective fire-resistant additives were being sought for polymers, textiles, and coatings.
Early research into phosphate esters was motivated by the need for non-flammable alternatives in plastics and building materials, as well as by the rapid expansion of the synthetic polymer industry.
By the mid-20th century, phosphate esters such as triphenyl phosphate and tricresyl phosphate were already widely used, and specialized mixed esters like Phenyl butyl phosphate were introduced to combine the stability of aromatic substituents with the flexibility of aliphatic groups, yielding additives with improved balance between flame retardancy, solubility, and plasticizing efficiency.
Over time, Phenyl butyl phosphate gained further attention in the lubricants and hydraulic fluids industry, as organophosphate esters demonstrated excellent anti-wear and thermal stability properties under demanding conditions.
Today, while not as historically famous as other organophosphates, Phenyl butyl phosphate is recognized as part of the broader legacy of phosphate ester development that transformed material science, safety standards, and industrial chemistry during the 20th century.
Handling and Storage of Phenyl Butyl Phosphate:
Handle in well-ventilated areas; avoid inhalation of vapors and contact with skin or eyes.
Do not eat, drink, or smoke when using this chemical.
Keep containers tightly closed when not in use.
Store in a cool, dry, and well-ventilated place, away from direct sunlight, heat sources, strong oxidizing agents, and strong acids or bases.
Use only in chemically resistant containers to prevent corrosion or leaks.
Stability and Reactivity of Phenyl Butyl Phosphate:
Stability:
Stable under normal conditions of handling and storage.
Decomposition:
May release irritating or toxic fumes (phosphorus oxides, hydrocarbons) upon heating.
Reactivity:
Reacts with strong oxidizing agents, acids, and bases; hydrolyzes slowly in moist conditions.
Hazardous Reactions:
Prolonged exposure to heat or incompatible chemicals can lead to decomposition.
First Aid Measures of Phenyl Butyl Phosphate:
Inhalation:
Move the affected person to fresh air.
Provide oxygen or artificial respiration if needed.
Seek medical attention if symptoms persist.
Skin Contact:
Wash immediately with soap and plenty of water.
Remove contaminated clothing.
Get medical attention if irritation develops.
Eye Contact:
Rinse cautiously with water for at least 15 minutes, holding eyelids open.
Seek medical help if irritation continues.
Ingestion:
Rinse mouth with water.
Do not induce vomiting.
Get immediate medical attention.
Firefighting Measures of Phenyl Butyl Phosphate:
Suitable Extinguishing Media:
Use foam, dry chemical, or carbon dioxide; water spray can be used to cool containers.
Hazards from Combustion:
Decomposition may release toxic fumes including phosphorus oxides (POₓ) and carbon oxides.
Protective Equipment:
Firefighters should wear self-contained breathing apparatus (SCBA) and full protective clothing.
Fire/Explosion Risk:
Not highly flammable, but can burn if exposed to high heat.
Accidental Release Measures of Phenyl Butyl Phosphate:
Personal Precautions:
Evacuate area if necessary; wear protective clothing, gloves, and goggles.
Ensure adequate ventilation.
Environmental Precautions:
Prevent leakage into drains, surface water, or soil, as phosphate esters may cause contamination.
Cleanup Methods:
Absorb spilled material with inert absorbents (sand, earth, vermiculite).
Collect into suitable containers for disposal.
Wash contaminated area with water and detergent.
Exposure Controls / Personal Protective Equipment of Phenyl Butyl Phosphate:
Engineering Controls:
Ensure local exhaust ventilation to keep airborne concentrations below recommended limits.
Respiratory Protection:
If ventilation is inadequate, use an approved respirator (organic vapor cartridge).
Skin Protection:
Wear chemical-resistant gloves (nitrile, neoprene).
Eye Protection:
Safety goggles or face shield.
Body Protection:
Protective clothing or lab coat; in industrial settings, chemical-resistant overalls recommended.
Hygiene Measures:
Wash hands thoroughly after handling; avoid prolonged or repeated exposure.
Identifiers of Phenyl Butyl Phosphate:
Chemical Name: Phenyl butyl phosphate
IUPAC Name: Butyl phenyl hydrogen phosphate (common naming for mono-ester form)
Phosphoric acid, phenyl butyl ester
Molecular Formula: C₁₀H₁₅O₄P
Molecular Weight: ~230.20 g/mol
InChI: InChI=1S/C10H15O4P/c1-2-3-4-14-15(11,12)13-10-8-6-5-7-9-10/h5-9H,2-4H2,1H3,(H2,11,12)
SMILES: CCCCOP(=O)(O)OC1=CC=CC=C1
Chemical Name: Phenyl butyl phosphate
IUPAC Name: Butyl phenyl phosphate (monosubstituted phosphate ester)
Systematic Name: Phosphoric acid, butyl phenyl ester
Molecular Formula: C₁₀H₁₅O₄P
Molar Mass: 230.20 g/mol
Composition:
Carbon: 52.2%
Hydrogen: 6.6%
Oxygen: 27.8%
Phosphorus: 13.4%
HS Code: 291990 (other phosphoric esters and their salts).
InChI: InChI=1S/C10H15O4P/c1-2-3-4-14-15(11,12)13-10-8-6-5-7-9-10/h5-9H,2-4H2,1H3,(H2,11,12)
InChI Key: ZPNVYQULUPDLBM-UHFFFAOYSA-N
SMILES: CCCCOP(=O)(O)OC1=CC=CC=C1
Properties of Phenyl Butyl Phosphate:
Boiling point: 245-260°C
Density: 1.180 g/cm3(Temp: 25 °C)
Pour Point: -25
Refractive index: 1.555
Fp: 224°C
Solubility: Acetone (Slightly), Ethyl Acetate (Slightly), Methanol (Slightly)
Form: Low-Melting Solid
Color: White to Pale Yellow
Water Solubility: <0.1 g/100 mL at 21 ºC
CAS DataBase Reference: 56803-37-3
EPA Substance Registry System: tert-Butylphenyl diphenyl phosphate (56803-37-3)
Chemical Formula: C₁₀H₁₅O₄P
Molecular Weight: 230.20 g/mol
Appearance: Colorless to pale yellow, oily liquid
Odor: Mild, ester-like
Class: Organophosphate ester
Density: ~1.15 g/cm³ (20 °C, estimated)
Boiling Point: >300 °C (decomposes before boiling)
Melting Point: Not well-defined (liquid at room temperature)
Vapor Pressure: Very low (non-volatile under ambient conditions)
Refractive Index (nD20): ~1.49–1.51 (typical for phosphate esters)
Viscosity: Moderate; suitable for use in lubricants and coatings
Solubility:
Water: Slightly soluble (<1%)
Organic solvents: Miscible with alcohols, ketones, hydrocarbons, esters
pH (aqueous suspension): Neutral to slightly acidic
