Hypophosphorous acid
CAS 6303-21-5
EC 228-601-5
Formula H3O2P
MW 66 g/mol
Inorganic Acids ElectronicsPharmaceuticals & HealthcareWater TreatmentTextile, Leather & Paper Antioxidant & StabilizerpH Regulation & Buffering
Description
Hypophosphorous acid (CAS 6303-21-5), also known as phosphinic acid, is an inorganic phosphorus-based acid supplied as a colourless oily liquid or hygroscopic crystalline solid. It carries no assigned E-code and is catalogued under EC 228-601-5 with the molecular formula H3O2P.
In electroless nickel plating, it acts as the primary reducing agent, donating electrons to deposit nickel onto non-conductive substrates without an external current. In pharmaceutical synthesis and water treatment, it functions as an antioxidant and pH buffer, inhibiting oxidative degradation and controlling process chemistry in sensitive formulations.
Hypophosphorous acid is available in technical and high-purity grades, with concentrations typically ranging from 50% to 100%. It is subject to REACH registration requirements within the EU. Standard packaging includes IBC containers and drums; procurement teams should confirm grade specifications against applicable pharmacopoeial or process standards before ordering.
In electroless nickel plating, it acts as the primary reducing agent, donating electrons to deposit nickel onto non-conductive substrates without an external current. In pharmaceutical synthesis and water treatment, it functions as an antioxidant and pH buffer, inhibiting oxidative degradation and controlling process chemistry in sensitive formulations.
Hypophosphorous acid is available in technical and high-purity grades, with concentrations typically ranging from 50% to 100%. It is subject to REACH registration requirements within the EU. Standard packaging includes IBC containers and drums; procurement teams should confirm grade specifications against applicable pharmacopoeial or process standards before ordering.
Physical Properties
| Melting Point | 26.5 °C |
| Boiling Point | 108 °C (759.8513 mmHg) |
| Density | 1.479 g/cm³ @ Temp: 20 °C |
| Appearance | colourless liquid |
| Color | Colorless |
| Form | hygroscopic crystals or colorless oily liquid |
| Water Solubility | SOLUBLE |
| Vapor Pressure | <17 mmHg ( 20 °C) |
| pH | pKa1= 1.00(25℃) |
Safety & Handling (Learn More)
Danger GHS05
H
H290H314H318
P
P234P260P264P280P316P317P321P363P390P405P406P501P264+P265P304+P340P301+P330+P331P302+P361+P354P305+P354+P338
Trade & Regulatory
| HS Code | 28111990 |
| UN Number | 3264 |
| ADR Class | 8 |
| Packing Group | III |
| Storage Class | 8B - Non-combustible corrosive hazardous materials |
| WGK (Germany) | 1 |
Other Names
phosphinic acidHPAhypophosphorousPhosphonous acidDihydroxyphosphineHYPOPHOSPHORUS ACID
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Raw Materials
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