Disodium phosphate dodecahydrate
[CAS# 10039-32-4]

Identification

• Classification: API >> Water, electrolyte and acid-base balance regulator >> Acid-base balance regulator
• Name: Disodium phosphate dodecahydrate
• Synonyms: Disodium hydrogen phosphate dodecahydrate; Sodium phosphate dibasic dodecahydrate
• Molecular Formula: Na₂HPO₄^.12(H₂O)
• Molecular Weight: 358.14
• CAS Registry Number: 10039-32-4
• EC Number: 600-088-6
• SMILES: O.O.O.O.O.O.O.O.O.O.O.O.OP(=O)([O-])[O-].[Na+].[Na+]

Properties

• Melting point: 35 ºC
• Water solubility: 218 g/L (20 ºC)

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H319
• Precautionary Statements: P264+P265-P280-P305+P351+P338-P337+P317

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319

Discovory and Applicatios

Disodium phosphate dodecahydrate, a hydrate form of disodium phosphate (Na2HPO4�12H2O), was first synthesized in the early 19th century. Chemists observed that by combining phosphoric acid with sodium hydroxide and allowing the solution to crystallize under controlled conditions, a stable hydrate form could be obtained. This compound, characterized by its twelve water molecules, provides unique stability and solubility properties compared to anhydrous forms. Its discovery facilitated various industrial and food applications due to its buffering capacity, making it an important compound in both chemical and food sciences.

Disodium phosphate dodecahydrate is extensively used as an additive in the food industry. It serves multiple functions such as an emulsifier, buffer, and sequestrant. In processed cheese production, it helps prevent separation of fats and proteins, maintaining a smooth texture. It also stabilizes and controls the pH in powdered and condensed milk, cream, and pudding mixes. Additionally, disodium phosphate enhances the performance of leavening agents in baking, improving dough texture and volume. Its ability to bind water makes it valuable in preventing crystallization and maintaining moisture in various food products, contributing to their shelf stability and quality.

In water treatment processes, disodium phosphate dodecahydrate is used as a corrosion inhibitor and a water softener. It helps control the formation of scale by binding with calcium and magnesium ions, preventing their precipitation as insoluble salts. This is particularly useful in industrial boilers and cooling systems, where scale can reduce efficiency and increase maintenance costs. By maintaining the solubility of these minerals, disodium phosphate enhances the longevity and efficiency of water-handling equipment, reducing downtime and operational costs.

Disodium phosphate dodecahydrate is used in the pharmaceutical industry for its buffering and osmotic properties. It serves as a pH adjuster in oral and injectable medications, ensuring drug stability and effectiveness. It is also employed in intravenous fluids to maintain electrolyte balance and in some laxative formulations to promote bowel movements. Additionally, it acts as a component in certain diagnostic reagents and laboratory buffers, playing a critical role in biochemical assays and research.

The compound is utilized in the formulation of detergents and cleaning agents due to its ability to sequester hard water ions and enhance the cleaning efficiency. In detergents, it improves soil removal by preventing the redeposition of dirt on fabrics and surfaces. Its buffering capacity helps maintain an optimal pH in cleaning solutions, enhancing the performance of surfactants and enzymes. Disodium phosphate is also used in industrial cleaning processes where its chelating properties aid in removing metal ions and preventing scale build-up on machinery and equipment.

In the chemical industry, disodium phosphate dodecahydrate is used as a reagent and intermediate in the production of various phosphate compounds. It is involved in the manufacture of water treatment chemicals, metal finishing solutions, and textile processing agents. Its buffering and sequestering properties are crucial in controlling reaction environments and improving product quality.