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Phosphorous acid

Description References
Phosphorous acid
Phosphorous acid structure
Chemical Name:
Phosphorous acid
Phosphonsure;AURORA KA-1076;PHOSPHORUS ACID;PHOSPHONIC ACID;orthophosphorus;ORTHOPHOSPHOROUS;Phosphorous acid;Phospohorous acid;O-PHOSPHOROUS ACID;PhosphorousAcid>98%
Molecular Formula:
Formula Weight:
MOL File:

Phosphorous acid Properties

Melting point:
73 °C
Boiling point:
200 °C
1.651 g/mL at 25 °C(lit.)
Flash point:
storage temp. 
pK1 1.29; pK2 6.74(at 25℃)
Specific Gravity
Water Solubility 
Air Sensitive & Hygroscopic
Stable. Incompatible with strong bases. Hygroscopic.
CAS DataBase Reference
13598-36-2(CAS DataBase Reference)
NIST Chemistry Reference
EPA Substance Registry System
Phosphonic acid(13598-36-2)
  • Risk and Safety Statements
Signal word  Danger
Hazard statements  H318-H290-H314-H302
Precautionary statements  P280-P305+P351+P338-P310-P260h-P301+P330+P331-P303+P361+P353-P405-P501a
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
HazardClass  8
PackingGroup  III
HS Code  28092019

Phosphorous acid price More Price(10)

Manufacturer Product number Product description CAS number Packaging Price Updated Buy
Sigma-Aldrich 04115 Phosphorous acid solution ≥50% 13598-36-2 1l $85.5 2018-11-13 Buy
Sigma-Aldrich 215112 Phosphorous acid 99% 13598-36-2 4x2kg $689 2018-11-13 Buy
Alfa Aesar 089407 Phosphorous acid, 97% 13598-36-2 2kg $133 2018-11-16 Buy
Alfa Aesar 089407 Phosphorous acid, 97% 13598-36-2 500g $36.9 2018-11-16 Buy
Sigma-Aldrich 215112 Phosphorous acid 99% 13598-36-2 100g $40 2018-11-13 Buy

Phosphorous acid Chemical Properties,Uses,Production


Phosphorous acid is an intermediate in the preparation of other phosphorous compounds. It is a raw material to prepare phosphonates for water treatment such as iron and manganese control, scale inhibition and removal, corrosion control and chlorine stabilization. The alkali metal salts (phosphites) of phosphorous acid are being widely marketed either as an agricultural fungicide (e.g. Downy Mildew) or as a superior source of plant phosphorous nutrition. Phosphorous acid is used in stabilizing mixtures for plastic materials. Phosphorous acid is used for inhibiting high-temperature of corrosion-prone metal surfaces and to produce lubricants and lubricant additives.


[1] Allison E. McDonald, Bruce R. Grant and William C. Plaxton, Phosphite (Phosphorous Acid): Its Relevance in The Environment and Agriculture and Influence on Plant Phosphate Starvation Response, Journal of Plant Nutrition, 2001, vol. 24, 1505-1519
[2] Sai-Shek Young, Stabilizers for plastic materials, Patent, 1993
[3] Guido Sartori, Method for inhibiting corrosion using phosphorous acid, Patent,2004
[4] John R Morris, Lubricant containing a phosphorous acid ester-aldehyde condensation product, Patent, 1956


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.

Chemical Properties

white crystalline solid


A colorless deliquescent solid that can be prepared by the action of water on phosphorus( III) oxide or phosphorus(III) chloride. It is a dibasic acid producing the anions H2PO3- and HPO3 2- in water. The acid and its salts are slow reducing agents. On warming, phosphonic acid decomposes to phosphine and phosphoric(V) acid.

General Description

A white or yellow crystalline solid (melting point 70.1 deg C) or a solution of the solid. Density 1.651 g /cm3 . Contact may severely irritate skin, eyes, and mucous membranes. Toxic by ingestion, inhalation and skin absorption.

Air & Water Reactions

Deliquescent. Absorbs oxygen from the air very readily to form phosphoric acid [Hawley]. Soluble in water.

Reactivity Profile

Phosphorous acid decomposes when heated to form phosphine, a gas that usually ignites spontaneously in air. Absorbs oxygen from the air to form phosphoric acid [Hawley]. Forms yellow deposits in aqueous solution that are spontaneously flammable upon drying. Reacts exothermically with chemical bases (for example: amines and inorganic hydroxides) to form salts. These reactions can generate dangerously large amounts of heat in small spaces. Dissolution in water or dilution of a concentrated solution with additional water may generate significant heat. Reacts in the presence of moisture with active metals, including such structural metals as aluminum and iron, to release hydrogen, a flammable gas. Can initiate the polymerization of certain alkenes. Reacts with cyanide compounds to release gaseous hydrogen cyanide. May generate flammable and/or toxic gases in contact with dithiocarbamates, isocyanates, mercaptans, nitrides, nitriles, sulfides, and strong reducing agents. Additional gas-generating reactions occur with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (to give SO2), and carbonates (to give CO2).

Health Hazard

TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Industrial uses

This collector was developed recently and was used primarily as specific collector for cassiterite from ores with complex gangue composition.On the basis of the phosphonic acid, Albright and Wilson had developed a range of collectors mainly for flotation of oxidic minerals (i.e. cassiterite, ilmenite and pyrochlore). Very little is known about the performance of these collectors. Limited studies conducted with cassiterite and rutile ores showed that some of these collectors produce voluminous froth but were very selective.

Safety Profile

Moderately toxic by ingestion. When heated to decomposition at 200℃ it emits toxic fumes of POx and phosphme whch may ignite. See also PHOSPHINE.

Phosphorous acid Preparation Products And Raw materials

Raw materials

Preparation Products

Phosphorous acid Suppliers

Global( 220)Suppliers
Supplier Tel Fax Email Country ProdList Advantage
Henan DaKen Chemical CO.,LTD.
+86-371-55531817 CHINA 21676 58
Hangzhou Bayee Chemical Co., Ltd.
0086-571-86990109; 0086-18605816692
0086-571-85775919 China 98 55
Henan Tianfu Chemical Co.,Ltd.
0371-55170693 CHINA 20672 55
Mainchem Co., Ltd.
+86-0592-6210733 CHINA 32447 55
Hefei TNJ Chemical Industry Co.,Ltd.
86-0551-65418684 18949823763
86-0551-65418684 China 1861 55
Chemwill Asia Co.,Ltd.
86-21-51861608;;; CHINA 23980 58
Hubei Jusheng Technology Co.,Ltd.
027-59599243 CHINA 28236 58
Haihang Industry Co.,Ltd
+86 531 8582 1093 CHINA 8921 58
Xiamen AmoyChem Co., Ltd
+86 592-605 1114 CHINA 6372 58
Hubei xin bonus chemical co. LTD
027-59338440 CHINA 23049 58

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