Home Categories Inorganic chemistry Phosphorous acid
A6637912

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

Update time: 2022-07-08

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.
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)

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
3
TSCA  Yes
HazardClass  8
PackingGroup  III
HS Code  28092019

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