Phosphorous acid

Phosphorous acid (CAS:13598-36-2) contains two ionizable hydroxyl groups in its molecular structure, so it is a dibasic acid and exists as both ortho and acid salts. Common ortho salts include potassium phosphite (K2HPO3), sodium phosphite (Na2HPO3), calcium phosphite (CaHPO3), aluminum phosphite [Al2(HPO3)3], ammonium phosphite [(NH4)2HPO3], and the corresponding acid salts include potassium dihydrogen phosphite (KH2PO3), calcium hydrogen phosphite [Ca(H2PO3)2] and so on. The raw materials used by different manufacturers, the production process is completely different, the export grade is generally prepared by hydrolysis of phosphorus trichloride PCl3.

Basic information

English name: Phosphorous acid

CAS No.: 13598-36-2

UN No.: 2834

EINECS No.: 237-066-7

Molecular formula: H3PO3

Molecular weight: 82

Melting point: 73.6℃

Decomposition temperature: 200℃

Solubility(20℃): 230g/100ml water

Density: 1.65g/cm³

Hazard Code: 81502

Hazardous category: 8

Hazardous Characteristics: Corrosive, heat decomposition produces harmful gas PH3.

Appearance: white crystal

Execution standard: HG/T2520-2006

Export tax rebate rate: 0%

Hazardous grade: Phosphorous acid exported in accordance with the transportation of dangerous goods of category 8

Nature of Waste: Hazardous Waste

Quantity of 20-foot small container: 20 tons with pallet; 25 tons without pallet; fumigation-free pallet or CP1-3 pallet; LCL is prohibited in most ports.

Product index

Content(Phosphorous acid)≥99.0%

Phosphate(PO4)≤0.2％

Chloride(Cl)≤0.01％

Sulphate(SO4)≤0.008%

Heavy metal(Pb)≤0.001%

Iron(Fe)≤0.001%

The principle of production and preparation

Phosphorous acid production of different raw materials, the principle of its production process is also different, by-products of phosphorous acid and phosphorus trichloride hydrolysis reaction principle has a big difference. PCl3 hydrolysis preparation principle is as follows: PCl3 + 3H2O → H3PO3 + 3HCl, the reaction can generate a large number of hydrochloric acid, with a very good benefit.

Product characteristics

1、High purity, good appearance, low odor

Phosphorous acid prepared by phosphorus trichloride PCl3 has good water solubility, almost no insoluble matter, low odor or even odorless, and its appearance is better than that of phosphite prepared by propionyl chloride, pivaloyl chloride, and by-product of dimethyl ester residue.

2, low iron ion content

Phosphorous acid prepared by hydrolysis of phosphorus trichloride PCl3 has iron ions ≤ 10ppm, which has little interference with the synthesis of chemicals. It is suitable for pharmaceutical intermediates, surface treatment, plastic flame retardants and other industries with high precision requirements.

3、Strong acidity, good stability

It is not easy to decompose and oxidize at room temperature, and its acidity is moderately strong among inorganic acids, and it is a relatively stable solid inorganic binary acid.

4, easy to absorb moisture

Easy to absorb moisture in humid air conditions, absorption of water dissolved corrosive greatly enhanced, the storage room needs to keep ventilated and dry. Avoid storing with oxidizing agents, alkaline chemicals and metal salts.

The main purpose

1, Phosphorous acid used in the production of new fertilizers, including potassium phosphite, potassium dihydrogen phosphite, ammonium phosphite and so on. Its +3-valent phosphorus and potassium dihydrogen phosphate have completely different mechanisms, with a certain sterilization, antiretroviral, and control the effect of exuberance. After later oxidized into phosphorus pentoxide P2O5, it can be used as effective phosphorus and potassium fertilizer for crop plants.

2, Phosphorous acid can be used for the production of aluminum phosphite halogen-free flame retardant, in nylon, PBT / PET and other materials and aluminum diethyl phosphonate complex can significantly improve the precipitation of flame retardants, the phenomenon of insufficient temperature resistance.

3, the acidity of phosphite is strong, the residue after decomposition and oxidation is generally phosphate, which is harmless to the environment, so it can also be used as a highly efficient corrosion inhibitor and scale inhibitor.

4, in chemical plating, electroplating industry can partially replace hypophosphorous acid, sodium hypophosphite, etc., and its reducibility and thermal stability is more advantageous than hypophosphite.

Phosphorous acid content of phosphorous acid is 37.8%, it can react with potassium hydroxide, sodium hydroxide, potassium carbonate and so on to generate salt, it can also have redox reaction with oxidizer, the product is phosphate. It has a wide range of applications in plastic stabilizers, pesticides, petrochemicals, fertilizer production, flame retardant synthesis, water treatment and other fields.