Pentasodium Triphosphate is an inorganic compound, a type of salt polyphosphate, a compound consisting of sodium ions and triphosphate ions.

The name defines the structure of the molecule:

• Pentasodium refers to the presence of five sodium ions in the compound.
• Triphosphate is a type of polyphosphate, a chain of phosphate groups linked by oxygen atoms. In this case, "tri-" indicates that there are three phosphate groups in the chain.

The synthesis process takes place in several stages:

• Formation of phosphoric acid: The first step in the synthesis of pentasodium triphosphate is the production of phosphoric acid with a reaction between phosphate and sulfuric acid.
• Phosphorus pentoxide formation: Phosphoric acid is dehydrated to form phosphorus pentoxide.
• Formation of polyphosphoric acid: Phosphorus pentoxide is hydrated to form polyphosphoric acid.
• Formation of pentasodium triphosphate: Finally, polyphosphoric acid is neutralized with sodium hydroxide to form Pentasodium Triphosphate.

What it is for and where

Food

Ingredient on the European food additives list as E451 acting as stabilising agent, emulsifier and bulking agent.

• E451 (i) Penta sodium tri phosphate 
• E451(ii) Penta potassium tri phosphate

Cosmetics

Buffering agent. It is an iingredient that can bring an alkaline or acid solution to a certain pH level and prevent it from changing, in practice a pH stabiliser that can effectively resist instability and pH change.

Chelating agent. It has the function of preventing unstable reactions and improving the bioavailability of chemical components within a product, and removes calcium and magnesium cations that can cause cloudiness in clear liquids.

Commercial applications

Detergents. It's used as a builder in detergents to enhance their cleaning properties, binding calcium and magnesium ions in water.

Food Industry. Acts as a stabilizer and preservative in some food products, such as frozen seafood, to maintain their texture.

Water Treatment. Used to soften water in industrial applications, binding minerals like calcium.

Ceramics. Used in ceramics production to enhance the plasticity of clay.

Pentasodium Triphosphate studies

• Molecular Formula: Na₅P₃O₁₀  Na₅O₁₀P₃
• Molecular Weight: 367.86 g/mol
• UNII: 9SW4PFD2FZ
• CAS: 7758-29-4  
• EC Number: 231-838-7  618-452-8

Synonyms:

• Sodium tripolyphosphate
• Pentasodium triphosphate
• STPP
• Thermphos
• Armofos
• Polygon
• Tripoly
• Triphosphoric acid, sodium salt (1:5)
• Sodium tripolyphosphate, anhydrous
• Rhodiaphos LV
• Thermphos N
• Empiphos stp-D
• Thermphos SPR
• Thermphos L 50
• PENTASODIUM TRIPOLYPHOSPHATE
• Triphosphoric acid, pentasodium salt
• Caswell No. 799
• Poly