Phosphorous acid , AR,99% , 13598-36-2
CAS NO.：13598-36-2
Empirical Formula: H3O3P
Molecular Weight: 82
MDL number: MFCD00137258
EINECS: 237-066-7
PRODUCT Properties
| Melting point: | 73 °C |
| Boiling point: | 200 °C |
| Density | 1.651 g/mL at 25 °C(lit.) |
| vapor pressure | 0.001Pa at 20℃ |
| Flash point: | 200°C |
| storage temp. | 0-6°C |
| solubility | DMSO (Slightly), Methanol (Slightly), Water (Sparingly) |
| form | Crystals |
| pka | pK1 1.29; pK2 6.74(at 25℃) |
| Specific Gravity | 1.651 |
| color | White |
| PH | pKa1= 1.10, pKa2 = 6.33(25℃) |
| Water Solubility | SOLUBLE |
| Sensitive | Air Sensitive & Hygroscopic |
| Merck | 14,7346 |
| Stability: | Stable. Incompatible with strong bases. Hygroscopic. |
Description and Uses
Phosphorous acid, H3PO3, is diprotic (readily ionizes two protons), not triprotic as might be suggested by this formula. Phosphorous acid is as an intermediate in the preparation of other phosphorous compounds. Because preparation and uses of “phosphorous acid” actually pertain more to the major tautomer, phosphonic acid, it is more often referred to as “phosphorous acid”. Phosphorous acid has the chemical formula H3PO3, which is best expressed as HPO(OH)2 to show its diprotic character. P(OH)3 (IUPAC: phosphorous acid) has CAS number 10294-56-1. It has been shown to be a stable tautomer.
Phosphorous acid is used to produce the fertilizer phosphate salt like potassium phosphite, ammonium phosphite and calcium phosphite. It is actively involved in the preparation of phosphites like aminotris(methylenephosphonic acid) (ATMP), 1-hydroxyethane 1,1-diphosphonic acid (HEDP) and 2-phosphonobutane-1,2,4-tricarboxylic Acid (PBTC), which find application in water treatment as a scale or corrosive inhibitor. It is also used in chemical reactions as a reducing agent. Its salt, lead phosphite is used as PVC stabilizer. It is also used as a precursor in the preparation of phosphine and as an intermediate in the preparation of other phosphorus compounds.
Safety
| Symbol(GHS) |   GHS05,GHS07 |
| Signal word | Danger |
| Hazard statements | H290-H302-H314 |
| Precautionary statements | P234-P270-P280-P301+P312-P303+P361+P353-P305+P351+P338 |
| 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 | Yes |
| HazardClass | 8 |
| PackingGroup | III |
| HS Code | 28092019 |
