What Is Triphenyl Phosphite (TPPi)?
Triphenyl phosphite (TPPi) is an important organophosphorus compound with the molecular formula C18H15O3P, a molecular weight of 310.28 and the CAS number 101-02-0. In its structure, a central phosphorus atom is bonded to three phenoxy groups. Industrial products with a purity of 97% are usually colorless to light yellow transparent liquids with a slight phenolic odor. The compound is poorly soluble in water, with water solubility below 0.1 g/100 mL, and is readily soluble in organic solvents such as ethanol, ether and benzene.
Physical and Chemical Properties
The following table lists the typical properties of triphenyl phosphite.
| Property | Value |
| Chemical Name | Triphenyl Phosphite |
| CAS Number | 101-02-0 |
| Molecular Formula | C18H15O3P |
| Molecular Weight | 310.28 g/mol |
| Appearance | Colorless to light yellow liquid |
| Odor | Slight phenolic odor |
| Water Solubility | Below 0.1 g/100 mL |
| Solubility in Organic Solvents | Soluble in ethanol, ether, benzene |
Chemically, the TPPi molecule contains a phosphorus-oxygen bond system and phenoxy groups, and it is easily hydrolyzed in the presence of moisture to form phenol and phosphorous acid. It may react violently when it encounters strong acids or strong oxidants, so contact with such materials should be strictly avoided.
Applications as a Polymer Material Stabilizer
Triphenyl phosphite is widely used as an auxiliary antioxidant and stabilizer for plastics such as PVC, polyethylene and polypropylene. As a secondary antioxidant, it decomposes hydroperoxides formed during polymer degradation, helping to inhibit thermal oxidative aging and improve processing stability. It is often used in pipes, films, artificial leather and cable compounds, where it contributes to color retention, long-term heat stability and reduced gel formation during processing.
Role in Organic Synthesis and Catalysis
In the pesticide industry, TPPi is used to synthesize organophosphorus insecticides, including intermediates for products such as chlorpyrifos. In the pharmaceutical field, it participates in phosphorylation reactions of drug molecules. As a reagent in the Wittig reaction, it is used in olefin synthesis for carbon-carbon double bond construction. In catalysis, TPPi combines with metal salts to form homogeneous catalyst systems used for olefin polymerization, carbonylation and hydroformylation reactions, where the phosphite ligand helps tune the activity and selectivity of the metal center.
Applications in Coatings and Adhesives
In coatings and adhesives, triphenyl phosphite improves the weather resistance and flexibility of systems such as epoxy resins and polyurethanes. It helps reduce oxidative discoloration during the curing process and stabilizes the polymer network against heat and light aging, extending the service life of finished coatings, sealants and adhesive films.
Storage, Handling and Safety Guidance
Triphenyl phosphite should be sealed and stored in a cool, dry place at a temperature at or below 30 °C, away from direct sunlight, moisture, strong acids and strong oxidants. Containers must be kept tightly closed after use, because moisture can cause hydrolysis and the gradual formation of phenol and phosphorous acid, which may darken the product and reduce its effectiveness. Operators should wear chemical-resistant gloves, safety goggles and protective clothing, and use local ventilation to avoid inhalation of vapors. Spills should be contained and absorbed with inert material, and waste should be disposed of in accordance with applicable environmental regulations.
Frequently Asked Questions
What is the CAS number of triphenyl phosphite?
The CAS number of triphenyl phosphite is 101-02-0, and its molecular formula is C18H15O3P with a molecular weight of 310.28.
Why is triphenyl phosphite used in plastics?
It acts as a secondary antioxidant and heat stabilizer that decomposes hydroperoxides and inhibits thermal oxidative aging, improving processing stability and long-term performance of PVC, PE and PP products.
Is triphenyl phosphite soluble in water?
No. Triphenyl phosphite has very low water solubility, below 0.1 g/100 mL, and is soluble in organic solvents such as ethanol, ether and benzene.
What happens if triphenyl phosphite contacts water?
It slowly hydrolyzes to form phenol and phosphorous acid, which can cause discoloration and reduce stabilizer performance, so containers must be kept tightly sealed and dry.
Can triphenyl phosphite be used as a catalyst ligand?
Yes. TPPi combines with metal salts to form homogeneous catalysts used in olefin polymerization, carbonylation and related reactions, where the phosphite ligand modulates activity and selectivity.
How should triphenyl phosphite be stored?
Store it sealed in a cool, dry place at or below 30 °C, away from sunlight, moisture, strong acids and strong oxidants, and keep containers closed after each use.