Phosphorous acid serves as an important intermediate for synthesizing various phosphorus compounds. It is a key raw material for producing phosphonates used in water treatment, including iron and manganese control, scale prevention and removal, corrosion inhibition, and chlorine stabilization. Its alkali metal salts (phosphites) are widely applied as agricultural fungicides (e.g., for Downy Mildew) and as an excellent source of plant phosphorus nutrition. Additionally, phosphorous acid is employed to stabilize plastic mixtures, protect corrosion-prone metal surfaces at high temperatures, and manufacture lubricants and lubricant additives.
Phosphorous acid CAS#13598-36-2
Serves as a key intermediate for the preparation of various phosphorus compounds.
Used to produce phosphonates for water treatment, including scale inhibition, corrosion control, and chlorine stabilization.
Alkali metal salts (phosphites) act as effective agricultural fungicides and high-quality sources of plant phosphorus nutrition.
Functions in stabilizing plastic mixtures, protecting corrosion-prone metal surfaces at high temperatures, and producing lubricants and lubricant additives.
Product Details
Phosphorous Acid CAS#13598-36-2
Phosphorous acid Chemical Properties
| Melting point | 73 °C |
| Boiling point | 200 °C |
| density | 1.651 g/mL at 25 °C(lit.) |
| vapor pressure | 0.001Pa at 20℃ |
| Fp | 200°C |
| storage temp. | 0-6°C |
| solubility | DMSO (Slightly), Methanol (Slightly), Water (Sparingly) |
| pka | pK1 1.29; pK2 6.74(at 25℃) |
| form | Crystals |
| color | White |
| Specific Gravity | 1.651 |
| PH | pKa1= 1.10, pKa2 = 6.33(25℃) |
| Water Solubility | SOLUBLE |
| Sensitive | Air Sensitive & Hygroscopic |
| Merck | 147346 |
| Stability: | Stable. Incompatible with strong bases. Hygroscopic. |
| InChI | 1S/H3O3P/c1-4(2)3/h4H,(H2,1,2,3) |
| InChIKey | ABLZXFCXXLZCGV-UHFFFAOYSA-N |
| SMILES | [H]P(O)(O)=O |
| CAS DataBase Reference | 13598-36-2(CAS DataBase Reference) |
| NIST Chemistry Reference | (HO)2HPO(13598-36-2) |
| EPA Substance Registry System | Phosphonic acid (13598-36-2) |
Safety Information
| Hazard Codes | C |
| Risk Statements | 22-35 |
| Safety Statements | 26-36/37/39-45 |
| RIDADR | UN 2834 8/PG 3 |
| WGK Germany | 1 |
| RTECS | SZ6400000 |
| F | 3 |
| TSCA | TSCA listed |
| HazardClass | 8 |
| PackingGroup | III |
| HS Code | 28092019 |
| Storage Class | 8A - Combustible corrosive hazardous materials |
| Hazard Classifications | Acute Tox. 4 Oral |
| Eye Dam. 1 | |
| Met. Corr. 1 | |
| Skin Corr. 1A |
Product Application of Phosphorous Acid CAS#13598-36-2
Phosphorous acid (H₃PO₃, orthophosphorous acid) can serve as a key reactant in the synthesis of:
α-aminomethylphosphonic acids through Mannich-type multicomponent reactions
1-aminoalkanephosphonic acids via amidoalkylation followed by hydrolysis
N-protected α-aminophosphonic acids (phospho-isosteres of natural amino acids) through amidoalkylation reactions
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