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Phosphorous Acid Identification Synonyms:Orthophosphorous acid; phosphonic acid (IUPAC) De: Phosphonsäure ES: Ácido fosfónico Fr:Acide phosphonique CAS No.: 13598-36-2 EC No.: 233-663-1 RTECS No.: SZ6400000 Molecular Weight:81.996 Molecular Formula: H3PO3 Density: 1.6510 M.P.: 73.6°C B.P.: 200°C (decomposing at 180°C) Physical & Chemical Properties: Phosphorous acid is a white, solid, reducing, diprotic (not triprotic as its formula suggests) acid, hygroscopic and deliquescent. It exists in equilibrium with a minor tautomer P(OH)3. IUPAC recommendations, 2005, are that the latter is called phosphorous acid, whereas the dihydroxy form is called phosphonic acid. Preparation 1) Phosphorous acid is the product of the hydrolysis of its acid anhydride: P4O6 + 6 H2O → 4 HPO(OH)2 2) On an industrial scale, phosphorous acid is prepared by hydrolysis of phosphorus trichloride with water or steam: PCl3 + 3 H2O-> HPO(OH)2 + 3HCl 3) Potassium phosphite is also a convenient precursor to phosphorous acid: K2HPO3 + 2 HCl-> 2 KCl + H3PO3 In practice aqueous potassium phosphite is treated with excess hydrochloric acid. By concentrating the solution and precipitations with alcohols, the pure acid can be separated from the salt. Wanjie International adopts 2) to make quality product. For more information, please contact us. Application 1)The most important use of phosphorous acid is the production of phosphonates, for example ATMP, HEDP, PBTC which are used as scale inhabitor or corrosive inhabitor in water treatment, and PMIDA (CAS 5994-61-6) which is a very important intermediate of herbicide glyphosate. 2)Phosphorous acid is also used for preparing phosphite salts, such as potassium phosphite, ammonium phosphite and calcium phosphite. These salts, as well as aqueous solutions of pure phosphorous acid, have shown effectiveness in controlling a variety of microbial plant diseases, in particular, treatment using either trunk injection or foliar containing phosphorous acid salts is indicated in response to infections by phytophthora and pythium-type plant pathogens (both within class oomycetes, known as water molds), such as dieback/root rot and downy mildew. Anti-microbial products containing salts of phosphorous acid are marketed in Australia as 'Yates Anti-Rot'; and in the United States of America, for example, aluminum salts of phosphorous acid (known generically as 'Fosetyl-Al') are sold under the trade name 'Aliette'. Another important phosphite salt is lead phosphite dibasic which is used as PVC stabilizer. 3)Phosphorous acid is also used in chemical reactions as a reducing agent that is somewhat less vigorous than the related hypophosphorous acid. 4)Upon heating to around 200 °C, it is a convenient precursor to phosphine: 4H3PO3 ->PH3 + 3H3PO4 Specification Parameters Specification Grade I Grade II Grade III 70% Solution Phosphorous acid content99.0% min. 98.5% min. 98.5% min. 70% min. Chloride (Cl-) 20ppm max. 50ppm max. 0.01% max. 50ppm max. Iron (Fe) 10ppm max. 20ppm max. 50 ppm max. 10ppm max. Sulfate (SO42-) 10ppm max. 20ppm max. 60 ppm max. 60ppm max. Phosphate (PO43-) 0.1% max. 0.2% max. 0.3% max. 0.1% max. Color, 70% solution APHA<20 APHA<30 APHA<50 APHA<20 Odor odorless odorless odorless odorless Appearance white crystals white crystals white crystals clear colorless liquid Standard Packing 1) 25kgs/PP woven bag with double PE inner bags, 20 25mt/20’ FCL 2) 500, 1000kgs/jumbo bag, 20mt/20’ FCL 3) Iron drum or Plastic drum 4) For 70% solution, packing is 25kg/plastic drum, 250kg/plastic drum or 1300kg/IBC Risks and Safety Info Class 8; UN2834; PG III R 22 Harmful if swallowed. R 35 Causes severe burns. S 26 In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S 36/37/39 Wear suitable protective clothing, gloves and eye/face protection. S 45 In case of accident or if you feel unwell, seek medical advice immediately (show the label where possible).