HYPOPHOSPHOROUS ACID

Hypophosphorous acid, or Phosphinic acid, is a phosphorus oxyacid and a powerful reducing agent with molecular formula H3PO2.

Hypophosphorous acid is a colorless low-melting compound, which is soluble in water, dioxane, and alcohols.

Hypophosphorous acid is used in articles, in formulation or re-packing, at industrial sites and in manufacturing.

CAS Number: 6303-21-5

EC Number: 228-601-5

Chemical Frmula: H3PO2

Molar Mass: 66.00 g/mol

Synonyms: 12164-97-5 [RN], 228-601-5 [EINECS], hydroxyphosphanone, MFCD02183592 [MDL number], Phosphenous acid [ACD/Index Name], Phosphinic acid [ACD/Index Name] [ACD/IUPAC Name], phosphinic-acid, phosphorus dioxide, Phosphorus oxide (PO2), 10039-56-2 [RN], 15460-68-1 [RN], 60062-19-3 [RN], 68412-68-0 [RN], 68412-69-1 [RN], 7789-79-9 [RN], HOPO, HPA, HPH2O2, hydrophosphorous acid, hydroxidooxidophosphorus, hydroxyl phosphine oxide, Hydroxyphosphine oxide, hypophosphite [Wiki], HYPOPHOSPHITE ION, Hypophosphoric acid [ACD/Index Name], Phosphine oxide, hydroxy-, PHOSPHINYLOXY, phosphorus(IV) oxide, Hypophosphorous acid [NF] [Wiki], 6303-21-5 [RN], Acide phosphinique [French] [ACD/IUPAC Name], H2PO(OH) [Formula], Hypophosphorous acid (VAN), PH2(OH)O [Formula], PH2O(OH) [Formula], Phosphinic acid [ACD/Index Name] [ACD/IUPAC Name], Phosphinsäure [German] [ACD/IUPAC Name], [PH2(OH)O], [PH2O(OH)], dihydridodioxophosphoric acid, dihydridohydroxidooxidophosphorus, dihydroxyphosphanium, dihydroxyphosphonium, H3PO2, HPA, hydrophosphorous acid, Hypophosphorous acidmissing, MFCD02183592 [MDL number], UNII-8B1RL9B4ZJ, 次磷酸 [Chinese]

Hypophosphorous acid is an ingredient to many etching solutions, such as solutions for etching of Al (Aluminum), GaAs (gallium arsenide), InP (indium phosphide), Ag (silver) or ZnO (zinc oxide).

Very hot concentrated phosphoric acid can also be used for etching of SiNx (silicon nitride).

Hypophosphorous acid is a phosphorus oxoacid and a powerful reducing agent.

Inorganic chemists refer to the free acid by this name (also as “HPA”) although Hypophosphorous acid official IUPAC name is Hypophosphorous acid.

Hypophosphorous acid is a colorless low-melting compound, which is soluble in water, dioxane, and alcohols.

The formula for Hypophosphorous acid is generally written H3PO2, but a more descriptive presentation is HOP(O)H2 which highlights Hypophosphorous acid monoprotic character.

Salts derived from this acid are called hypophosphites.

HOP(O)H2 exists in equilibrium with the minor tautomer HP(OH)2. 

Sometimes the minor tautomer is called Hypophosphorous acid and the major tautomer is called Hypophosphorous acid.

Hypophosphorous acid derivatives exhibit diverse biological activities and a high degree of structural diversity, rendering them a versatile tool in the development of new medicinal agents.

Hypophosphorous acid is an oxoacid of phosphorus.

Hypophosphorous acid chemical formula is H3PO2.

Hypophosphorous acid also known as Phosphinic acid is a phosphorous oxoacid and also acts as a good reducing agent.

Hypophosphorous acid is basically a colourless aqueous solution that is soluble in water, dioxin as well as in alcohol.

Hypophosphorous acid formula is H3PO2 is a neutral molecule with no spare charge on it.

Thus the oxidation number of the central atom phosphorus is +1 which can be described as follows.

As the whole charge on the H3PO2 molecule is zero.

Charge on a single hydrogen atom is one and there are three atoms present in the molecules that make Hypophosphorous acid 3.

Similarly, the valency of a single oxygen atom is (-2) and there are 2 oxygen atoms present in the molecule.

Thus the formula would be considering the oxidation state of the phosphorus atom as unknown as therefore represented as X.

1x31x3 + X +(−2)x2 (−2)x2 = 3 – 4 + X = -1 + X or, X = 1.

Hypophosphorous acid formula that has a more precise and descriptive presentation as HOP(O)H2 which is the actual Hypophosphorous acid chemical formula that actually represents the monoprotic characteristics by the later molecular formula.

HOP(O)H2 is in equilibrium with the minor structural formula of Hypophosphorous acid that is interconvertible like HP(OH)2.

The minor tautomers are referred to as Hypophosphorous acid and the major monomers are called Hypophosphorous acid.

Hypophosphorous acid compounds (phosphinates) are derivatives of Hypophosphorous acid H 2 P(O)(OH). 

Hypophosphorous acid peptides (phosphinic pseudopeptides) are peptide isosteres where one peptide bond is substituted by the nonhydrolysable phosphinate moiety -P(O)(OH)-CH 2 – or -P(O)(OH)-. 

This substitution represents a very convenient mimic of a substrate in the transition state for at least two distinct classes of hydrolytic enzymes, Zn-metalloproteinases and aspartic acid proteinases. 

These proteins are mainly proteinases, however other types of proteins such as transferases, synthetases, ligases or even receptors are also discussed. 

Genome sequencing projects have been identifying protein sequences faster than Hypophosphorous acid is possible to discover their functions. 

The development of combinatorial chemistry in the past few years has boosted up the interest in the use of chemistry to address biological problems. 

Phosphinates, especially in conjunction with combinatorial chemistry approaches, represent an extremely versatile tool in the search for proteome and Hypophosphorous acid function.

Hypophosphorous acid is registered under the REACH Regulation and is manufactured in and / or imported to the European Economic Area, at ≥ 100 to < 1 000 tonnes per annum. Hypophosphorous acid is used in articles, in formulation or re-packing, at industrial sites and in manufacturing. Hypophosphorous acid (HPA), or Hypophosphorous acid, is a phosphorus oxyacid and a powerful reducing agent with molecular formula H3PO2. Hypophosphorous acid is a colorless low-melting compound, which is soluble in water, dioxane, and alcohols. Hypophosphorous acid, or Hypophosphorous acid, is a phosphorus oxyacid and a powerful reducing agent with molecular formula H3PO2. Hypophosphorous acid is a colorless low-melting compound, which is soluble in water, dioxane and alcohols. The formula for this acid is generally written H3PO2, but a more descriptive presentation is HOP(O)H2, which highlights Hypophosphorous acid monoprotic character. Salts derived from this acid are called hypophosphites. HOP(O)H2 exists in equilibrium with the minor tautomer HP(OH)2. Sometimes the minor tautomer is called Hypophosphorous acid and the major tautomer is called Hypophosphorous acid. The formula for Hypophosphorous acid is generally written H3PO2, but a more descriptive presentation is HOP(O)H2, which highlights Hypophosphorous acid monoprotic character. Salts derived from Hypophosphorous acid are called hypophosphites. HOP(O)H2 exists in equilibrium with the minor tautomer HP(OH)2. Sometimes the minor tautomer is called Hypophosphorous acid and the major tautomer is called Hypophosphorous acid. Hypophosphorous acid is a phosphorus oxoacid that consists of a single pentavalent phosphorus covalently bound via single bonds to two hydrogens and a hydroxy group and via a double bond to an oxygen.J Hypophosphorous acid has role antioxidant. Hypophosphorous acid is a phosphorus oxoacid. Hypophosphorous acid is conjugate acid of phosphinate. Hypophosphorous acid is a powerful reducing agent with a molecular formula of H3PO2. Inorganic chemists refer to the free acid by this name although Hypophosphorous acid IUPAC name is dihydridohydroxidooxidophosphorus, or the acceptable name of Hypophosphorous acid. Hypophosphorous acid is a colorless low-melting compound, which is soluble in water, dioxane, and alcohols. The formula for Hypophosphorous acid is generally written H3PO2, but a more descriptive presentation is HOP(O)H2 which highlights Hypophosphorous acid monoprotic character. Salts derived from this acid are called phosphinates (hypophosphites). In organic chemistry, H3PO2 best known for their use in the reduction of arenediazonium salts, converting ArN2+ to Ar-H. When diazotized in a concentrated solution of Hypophosphorous acid, an amine substituent can be removed from arenes, selectively over alkyl amines. Hypophosphorous acid (HPA) is also known as Hypophosphorous acid, hydroxy(oxo)-λ5-phosphane, oxo-λ5-phosphinous acid and oxo-λ5-phosphanol. Hypophosphorous acid molecular formula is H3PO2 or HOP(O)H2. Hypophosphorous acid is a hydroxy phosphine oxide or phosphorus oxyacid having a monobasic character. Hypophosphorous acid is a low-melting colorless compound, which is highly soluble in alcohols, dioxane and water. Hypophosphoric acid is a mineral acid with the formula H4P2O6, with phosphorus in a formal oxidation state of +4. In the solid state Hypophosphorous acid is present as the dihydrate, H4P2O6·2H2O. In hypophosphoric acid the phosphorus atoms are identical and joined directly with a P−P bond. Isohypophosphoric acid is a structural isomer of hypophosphoric acid in which one phosphorus has a hydrogen directedly bonded to Hypophosphorous acid and that phosphorus atom is linked to the other one by an oxygen bridge to give a phosphorous acid/phosphoric acid mixed anhydride. The two phosphorus atoms are in the +3 and +5 oxidation states, respectively. Hypophosphorous acid is a phosphorus oxoacid that consists of a single pentavalent phosphorus covalently bound via single bonds to two hydrogens and a hydroxy group and via a double bond to an oxygen. Hypophosphorous acid has a role as an antioxidant. Hypophosphorous acid is a phosphorus oxoacid and a member of Hypophosphorous acids. Hypophosphorous acid is a conjugate acid of a phosphinate. Hypophosphorous acid is an important chemical product with wide applications in pharmaceuticals and electroless plating. Free Hypophosphorous acid is prepared by acidifying aqueous solutions of hypophosphite ions, H2PO2−.  For example, the solution remaining when phosphine is prepared from the reaction of white phosphorus and a base contains the H2PO2− ion.  If barium hydroxide (BaOH) is used as the base and the solution is acidified with sulfuric acid, barium sulfate, BaSO4, precipitates, and an aqueous solution of Hypophosphorous acid results. Ba2+ + 2H2PO2− + 2H3O+ + SO42− → BaSO4 + 2H3PO2 + 2H2O The pure acid cannot be isolated merely by evaporating the water, however, because of the easy oxidation of the phosphoric acids (and elemental phosphorus) and Hypophosphorous acid disproportionation to phosphine and phosphorous acid.  The pure acid can be obtained by extraction of Hypophosphorous acid aqueous solution by diethyl ether, (C2H5)2O. Pure Hypophosphorous acid forms white crystals that melt at 26.5 °C (79.7 °F). The electronic structure of Hypophosphorous acid is such that Hypophosphorous acid has only one hydrogen atom bound to oxygen, and Hypophosphorous acid is thus a monoprotic oxyacid.  Hypophosphorous acid is a weak acid and forms only one series of salts, the hypophosphites.  Hydrated sodium hypophosphite, NaH2PO2 · H2O, is used as an industrial reducing agent, particularly for the electroless plating of nickel onto metals and nonmetals. Applications of Hypophosphorous acid: Hypophosphorous acid (and Hypophosphorous acid salts) are used to reduce metal salts back into bulk metals. Hypophosphorous acid is effective for various transition metals ions (i.e. those of: Co, Cu, Ag, Mn, Pt) but is most commonly used to reduce nickel. This forms the basis of electroless nickel plating (Ni–P), which is the single largest industrial application of hypophosphites. For this application Hypophosphorous acid is principally used as a salt (sodium hypophosphite). Hypophosphorous acid is primarily used for electroless nickel plating. Hypophosphorous acid is involved in the reduction of arenediazonium salts. Hypophosphorous acid acts as an additive in Fischer esterification reactions. Also, Hypophosphorous acid serves as a neutralizing agent, antioxidant, catalyst in polymerization and poly condensation, and wetting agent. Further, Hypophosphorous acid is used in the formulation of pharmaceuticals, discoloration of polymers, water treatment and retrieval of precious or non-ferrous metals. In addition to this, Hypophosphorous acid is used as bleaching agents for plastics, synthetic fibers, decolorizing agent and for color stabilization during the manufacture of chemicals and several plastics. Hypophosphorous acid is used as a pharmaceutical additive as antioxidant, as an ingredient of electroless plating solutions, for the retrieval of precious or non-ferrous metals as a water treatment agent, as a meat preservative to prevent the discoloration of polymers and for the production of chemicals Uses of Hypophosphorous acid: Hypophosphorous acid is used as a chain transfer agent in aqueous polymerizations. Hypophosphorous acid has color stabilizer function, antioxydant property and Hypophosphorous acid is also used as reducer or catalyst in multiple industries. Hypophosphorous acid is used in the formulation of pharmaceuticals, discoloration of polymers, water treatment, retrieval of precious or non-ferrous metals. Hypophosphorous acid main use is for electroless plating, i.e. deposition of metal films from solution. Hypophosphorous acid is majorly manufactured from Sodium Hypophosphite. Hypophosphorous acid is widely used as a reducing agent to reduce Cu, Hg and Ag etc. to verify impurities, such as Nb, As and Ta, etc. Hypophosphorous acid is also used as a catalyst during esterification and in medicines, Hypophosphorous acid is used to detect tellurium and arsenic, etc Hypophosphorous acid is used as a decolorizing or bleaching agent in plastics, chemicals and synthetic fibers. Hypophosphorous acid is also used as a color stabilizer during the manufacturing of chemicals and plastics, including polyamides, nylon fibers, polyacrilonitrile, polyester fiber, epoxies, glycerols, fatty acid esters and alkyd resins. Hypophosphorous acid is also used as a polycondensation and polymerization agent, reducing agent, an antioxidant and stimulant in pharmaceuticals, etc. Thus, due to the wide areas of application of Hypophosphorous acid, Hypophosphorous acid consumption is expected to grow at a significant rate during the forecast period. Hypophosphorous acid is used in various end use industries, such as building and construction, electronics and electrical, chemical and plastics, etc. Thus, owing to the growing use of Hypophosphorous acid in various industries, Hypophosphorous acid sales is expected to increase, thereby propelling the growth of the global Hypophosphorous acid market during the forecast period. Hypophosphorous acid is used as reducing agent for electroless plating. Hypophosphorous acid can be used to prevent discoloration of phosphoric acid resin. Hypophosphorous acid is used as esterification catalyst, the refrigerant. Hypophosphorous acid is used to produce hypophosphite, sodium salts, manganese salts, iron salts are generally used as nourishing substances. Hypophosphorous acid is used in medicine and as reducing agent, the determination of arsenic, tellurium and separation of tantalum, niobium and other reagents. Hypophosphorous acid is strong reducing agent, Hypophosphorous acid can be used for the preparation of sodium hypophosphite, calcium phosphate and other hypophosphite. Hypophosphorous acid can be used for the plating bath, pharmaceuticals, reducing agent, general reagents. Hypophosphorous acid is strong reducing agent, Hypophosphorous acid can be used in making sodium hypophosphite, calcium phosphate and other hypophosphite. Hypophosphorous acid is widely used as reducing agent, Ag, Cu, Ni, Hg and other metals are reduced to the corresponding metal, for the verification of As, Nb, Ta and other reagents, Hypophosphorous acid can be used for the preparation of Na, K, Ca, Mn, Fe and other types of hypophosphite. Bleaching Agent: Hypophosphorous acid is used as a bleaching or decolorizing agent for plastics, synthetic fibers, and chemicals Color Stabilizer: Hypophosphorous acid is used as a decolorizing agent and for color stabilization during the manufacture of chemicals and several plastics including: nylon fibers, polyamides, polyester fiber, polyacrilonitrile, alkyd rsins, epoxies, fatty acid esters, and glycerols. Hypophosphite Salts: Hypophosphorous acid is used in the production of Hypophosphite Salts (i.e., Calcium, Magnesium, Manganese, Potassium, Iron, and Ammonium) which are in turn used in synthetic fibers as wetting dispersing, emulsifying, and anti-static agents. Chemical Intermediate: Hypophosphorous acid is used in organic synthesis and organo Hypophosphorous acid production. Neturalizing Agent: Hypophosphorous acid is used as a moderately strong monobasic acid. Catalyst: Hypophosphorous acid is a polymerization and polycondensation catalyst. Wetting Agent: Hypophosphorous acid is a as a wetting, dispersing, or emulsifying agent in electroplating. Reducing Agent: Hypophosphorous acid may be used for Hypophosphorous acid strong but slow reducing action. Antioxidant: Hypophosphorous acid may be used as an antioxidant. Pharmaceutical: Hypophosphorous acid may be used as a stimulant in pharmaceuticals. Uses at industrial sites: Hypophosphorous acid is used in the following products: pH regulators and water treatment products, coating products, fillers, putties, plasters, modelling clay, finger paints, metal surface treatment products, non-metal-surface treatment products, laboratory chemicals, polymers, washing & cleaning products, water treatment chemicals and welding & soldering products. Hypophosphorous acid has an industrial use resulting in manufacture of another substance (use of intermediates). Hypophosphorous acid is used in the following areas: formulation of mixtures and/or re-packaging. Hypophosphorous acid is used for the manufacture of: chemicals and plastic products. Release to the environment of Hypophosphorous acid can occur from industrial use: in processing aids at industrial sites, as processing aid, as an intermediate step in further manufacturing of another substance (use of intermediates) and in the production of articles. Preparation and Availability of Hypophosphorous acid: Hypophosphorous acid was first prepared in 1816 by the French chemist Pierre Louis Dulong (1785–1838). The acid is prepared industrially via a two step process: Firstly, elemental white phosphorus reacts with alkali and alkaline earth hydroxides to give an aqueous solution of hypophosphites: P4 + 4 OH− + 4 H2O → 4 H2PO−2 + 2 H2 Any phosphites produced in this step can be selectively precipitated out by treatment with calcium salts. The purified material is then treated with a strong, non-oxidizing acid (often sulfuric acid) to give the free Hypophosphorous acid: H2PO−2 + H+ → H3PO2 Hypophosphorous acid is usually supplied as a 50% aqueous solution. Anhydrous acid cannot be obtained by simple evaporation of the water, as the acid readily oxidises to phosphorous acid and phosphoric acid and also disproportionates to phosphorous acid and phosphine. Pure anhydrous Hypophosphorous acid can be formed by the continuous extraction of aqueous solutions with diethyl ether. Preparation method of Hypophosphorous acid: 1. Phosphorus and barium hydroxide solution is heated,  barium salt Ba (H2PO2) 2 • 2H2O can generate, sulfuric acid is added into Hypophosphorous acid barium solution, Ba2+ can precipitate: Ba(H2PO2)2+H2SO4=BaSO4+2H3PO2 Hypophosphorous acid can be obtained by evaporating under reduced pressure and low temperature crystallization.  Due to in this process, the solubility of the barium salt is small, so the concentration of obtained Hypophosphorous acid is not high, industrial product should be purified by recrystallization. 2. the barium oxide (or lime) and solution of white phosphorus is heated together to form secondary barium phosphate (or calcium), and then reacts with sulfuric acid, Hypophosphorous acid is filtered, concentrated to obtain product, or sodium hypophosphite solution proceeds H-type ion exchange resin can derive product. This method requires a large amount of resin, and resin regeneration and washing step is cumbersome, Hypophosphorous acid generally costs more than $ 7 per pound, Hypophosphorous acid is only suitable for small batch production, and not suitable for large-scale industrial applications. 3. Hypophosphorous acid is prepared by electrodialysis method, wherein the electrodialysis cell divides into three parts, they are anode chamber, raw material chamber and cathode chamber, the intermediate is separated by anionic membrane and cationic membrane, between two membranes sodium hypophosphite solution is placed (concentration of 100g/L~500g/L), anode chamber is dilute solution of Hypophosphorous acid 5g/L, anode chamber is dilute sodium hydroxide solution ( 5g /L), between the poles DC (3V~36V) is passed, anode releases oxygen, and generates secondary product of Hypophosphorous acid; cathode emits hydrogen, and generates secondary product of sodium hydroxide, the reaction time is 3~21h.  The reactions of anode chamber and cathode chamber are as follows: Anode chamber: H2O==H++OH- 2OH-==O2+2H2O+4e H++H2PO2-==H3PO2 Cathode chamber: H2O==H++OH- 2H++2e==H2 Na++OH-==NaOH Electrodialysis method of preparation Hypophosphorous acid is simple and equipment investment is small, Hypophosphorous acid is suitable for mass production. 4. Starting from the industrial grade sodium hypophosphite, Cl-, SO42-anions which affect the quality indicators of Hypophosphorous acid are removed by precipitation, heavy metal ions are removed from the solution by forming sulfide, and then using strong acid cation exchange resin to obtain sodium secondary phosphate, high purity grade product can obtain. The process can produce high-grade secondary phosphate, technically is feasible, the process is simple, easy operation, good product quality, Hypophosphorous acid can meet the needs of the electronics industry, defense industry and other high-tech fields. 5. Ion exchange resin method: about 70g of cation exchange resin wetted with water is packed into a glass tube with 5 mol/L hydrochloric acid circulating about 15min, after thoroughly washed with water, high purity aqueous sodium hypophosphite aqueous solution (15 g/60 ml H2O) flows through it, the resin column is first washed with 50 ml, then with 25 rnl distilled water.  The effluent acid and washing is combined, Hypophosphorous acid is concentrated by evaporation in water bath.  The concentrated acid is placed in high vacuum with P205 dryer for dehydration, cooling and crystallization, filtration, recrystallization, to obtain Hypophosphorous acid product. Hypophosphate salts: Many hypophosphate salts are known, for example, K4P2O6·8H2O, Ca2P2O6·2H2O, K3HP2O6·3H2O, K2H2P2O6·2H2O, KH3P2O6. On standing in air, hypophosphates tend to oxidise to pyrophosphates containing the P2O4−7 ion where P has a formal oxidation state of +5. Hypophosphates are stable to alkali hydroxides. In fused sodium hydroxide they convert rapidly to the orthophosphate containing PO3−4. Structure of Hypophosphorous acid: Hypophosphorus acid contains oxonium ions and is best formulated [H3O+]2 [H2P2O6]2−. The acid is isostructural with the diammonium salt which contains the [HOPO2PO2OH]2− anion with a P−P bond length of 219 pm. The HOPO2PO2OH2− anion in Na2H2P2O6·6H2O has a symmetric, staggered ethane-like structure with a P−P bond of length 219 pm. Each phosphorus atom has two P−O bonds with length 151 pm, and a P−OH bond length of 159 pm. Chemical Structure of Hypophosphorous acid: A chemical structure of a molecule includes the arrangement of atoms and the chemical bonds that hold the atoms together. The Hypophosphorous acid molecule contains a total of 5 bond(s). There are 2 non-H bond(s), 1 multiple bond(s), 1 double bond(s), and 1 hydroxyl group(s). Formula of Hypophosphorous acid: Hypophosphoric acid is a mineral acid with phosphorus in an oxidation state of +4. Hypophosphorous acid has a chemical formula H4P2O6. In the solid-state, Hypophosphorous acid exists as a dihydrate, H4P2O6.2H2O. Hypophosphorous acid can be manufactured by reacting red phosphorus with sodium chlorite at room temperature. In this short piece of article, let us discuss the hypophosphoric acid formula along with Hypophosphorous acid chemical structure, properties and uses. Properties of Hypophosphorous acid: The molecule displays P(═O)H to P–OH tautomerism similar to that of phosphorous acid; the P(═O) form is strongly favoured. Hypophosphorous acid is usually supplied as a 50% aqueous solution and heating at low temperatures (up to about 90°C) prompts Hypophosphorous acid to react with water to form phosphorous acid and hydrogen gas. H3PO2 + H2O → H3PO3 + H2 Heating above 110°C causes Hypophosphorous acid to undergo disproportionation to give phosphorous acid and phosphine. 3 H3PO2 → 2 H3PO3 + PH3 Chemical properties: Hypophosphorous acid is deliquescent crystals or colorless oil.  Hypophosphorous acid is soluble in water, ethanol and ether, and Hypophosphorous acid can be mixed in any proportion with water, ethanol, acetone. In the air, Hypophosphorous acid easily deliquesce to syrupy liquid, and the aqueous solution is acidic. Hypophosphorous acid is monobasic acid, in aqueous solution, Hypophosphorous acid is strong acid, Ka = 10-2 (25℃). Hypophosphorous acid is relatively stable at room temperature. Disproportionation reaction can proceed at 130℃, decompose into phosphine and phosphorous acid: 2H3PO2=H3PO4+PH3 Hypophosphorous acid has strong reduction, heavy metal salt solution can be restored to metals such as Cu2 +, Hg2 +, Ag +, such as: 4Ag+H3PO2+2H2)=4Ag+H3PO4+4H+ Hypophosphorous acid is weak oxidizer, Hypophosphorous acid can be reduced to phosphine, phosphine when encounters strong reducing agent. Reactions of Hypophosphorous acid: Inorganic: Hypophosphorous acid can reduce chromium(III) oxide to chromium(II) oxide: H3PO2 + 2 Cr2O3 → 4 CrO + H3PO4 Inorganic derivatives: Most metal-hypophosphite complexes are unstable, owing to the tendency of hypophosphites to reduce metal cations back into the bulk metal. Some examples have been characterised, including the important nickel salt [Ni(H2O)6](H2PO2)2. DEA List I chemical status: Because Hypophosphorous acid can reduce elemental iodine to form hydroiodic acid, which is a reagent effective for reducing ephedrine or pseudoephedrine to methamphetamine, the United States Drug Enforcement Administration designated Hypophosphorous acid (and Hypophosphorous acid salts) as a List I precursor chemical effective November 16, 2001. Accordingly, handlers of Hypophosphorous acid or Hypophosphorous acid salts in the United States are subject to stringent regulatory controls including registration, recordkeeping, reporting, and import/export requirements pursuant to the Controlled Substances Act and 21 CFR §§ 1309 and 1310. Organic: In organic chemistry, H3PO2 can be used for the reduction of arenediazonium salts, converting ArN+2 to Ar–H. When diazotized in a concentrated solution of Hypophosphorous acid, an amine substituent can be removed from arenes. Owing to Hypophosphorous acid ability to function as a mild reducing agent and oxygen scavenger Hypophosphorous acid is sometimes used as an additive in Fischer esterification reactions, where Hypophosphorous acid prevents the formation of colored impurities. Hypophosphorous acid is used to prepare Hypophosphorous acid derivatives. Production method of Hypophosphorous acid: Ion exchange resin method: put about 70 g water-soluble cation exchange resins to fill into a glass tube.  Circulate with 5 mol/L hydrochloric acid for about 15 min and wash sufficiently with water.  Have a high aqueous sodium hypophosphite solution (15 g/60 ml H2O) to flow through the resin column, followed by being washed first with 50 ml water, and then rinsing with 25 rnl distilled water.  The effluent acid and the washings were combined and concentrated by evaporation on a water bath.  The concentrated acid is send to the highly vacuum, P205 dryer for dehydration, followed by cooling crystallization, filtration and recrystallization to obtain the finished product of Hypophosphorous acid. Handling and storage of Hypophosphorous acid: Precautions for safe handling: Handling in a well ventilated place. Wear suitable protective clothing. Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Use non-sparking tools. Prevent fire caused by electrostatic discharge steam. Conditions for safe storage, including any incompatibilities: Store the container tightly closed in a dry, cool and well-ventilated place. Store apart from foodstuff containers or incompatible materials. Stability and reactivity of Hypophosphorous acid: Reactivity: Deliquescent. Water soluble. Possibility of hazardous reactions: Hypophosphorous acid decomposes when heated into phosphoric acid and spontaneously flammable phosphine. Hypophosphorous acid is oxidized by sulfuric acid with release of sulfur dioxide and sulfur. Reacts explosively with mercury(II) oxide. Reacts violently with mercury(II) nitrate. Neutralizes bases in exothermic reactions. First-aid measures of Hypophosphorous acid: If inhaled: Move the victim into fresh air. If breathing is difficult, give oxygen. If not breathing, give artificial respiration and consult a doctor immediately. Do not use mouth to mouth resuscitation if the victim ingested or inhaled the chemical. Following skin contact: Take off contaminated clothing immediately. Wash off with soap and plenty of water. Consult a doctor. Following eye contact: Rinse with pure water for at least 15 minutes. Consult a doctor. Following ingestion: Rinse mouth with water. Do not induce vomiting. Never give anything by mouth to an unconscious person. Call a doctor or Poison Control Center immediately. Most important symptoms/effects, acute and delayed: 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. Indication of immediate medical attention and special treatment needed, if necessary: no data available Fire-fighting measures of Hypophosphorous acid: SMALL FIRE: Dry chemical, CO2 or water spray. LARGE FIRE: Dry chemical, CO2, alcohol-resistant foam or water spray. Move containers from fire area if you can do Hypophosphorous acid without risk. Dike fire-control water for later disposal; do not scatter Hypophosphorous acid. FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Do not get water inside containers. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. Specific hazards arising from the chemical: 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. Special protective actions for fire-fighters: Wear self-contained breathing apparatus for firefighting if necessary. Accidental release measures of Hypophosphorous acid: Personal precautions, protective equipment and emergency procedures: Avoid dust formation. Avoid breathing mist, gas or vapours. Avoid contacting with skin and eye. Use personal protective equipment. Wear chemical impermeable gloves. Ensure adequate ventilation. Remove all sources of ignition. Evacuate personnel to safe areas. Keep people away from and upwind of spill/leak. Environmental precautions: Prevent further spillage or leakage if Hypophosphorous acid is safe to do so. Do not let the chemical enter drains. Discharge into the environment must be avoided. Methods and materials for containment and cleaning up: Collect and arrange disposal. Keep the chemical in suitable and closed containers for disposal. Remove all sources of ignition. Use spark-proof tools and explosion-proof equipment. Adhered or collected material should be promptly disposed of, in accordance with appropriate laws and regulations. Identifiers of Hypophosphorous acid: CAS Number: 6303-21-5 ChEBI: CHEBI:29031 ChEMBL: ChEMBL2105054 ChemSpider:  10449263 10459437 (17O2)k 2342086 (2H3) ECHA InfoCard: 100.026.001 KEGG: D02334 PubChem CID: 3085127 (2H3) UNII: 8B1RL9B4ZJ UN number: UN 3264 CompTox Dashboard (EPA): DTXSID90206211 InChI: InChI=1S/H3O2P/c1-3-2/h3H2,(H,1,2) Key: ACVYVLVWPXVTIT-UHFFFAOYSA-N InChI=1/H3O2P/c1-3-2/h3H2,(H,1,2) Key: ACVYVLVWPXVTIT-UHFFFAOYAQ SMILES: O[PH2]=O CAS Numbers (All): 6303-21-5 EC Number: 228-601-5 Linear Formula: H3PO2 MDL Number: MFCD02183592 Molar Mass: 66.0 g/mol Synonyms: Hypophosphorous acid Synonym(s): Hypophosphorous acid Linear Formula: H3PO2 CAS Number: 6303-21-5 Molecular Weight: 66.00 MDL number: MFCD02183592 PubChem Substance ID: 329752159 NACRES: NA.21 Properties of Hypophosphorous acid: Chemical formula: H3PO2 Molar mass: 66.00 g/mol Appearance: colorless, deliquescent crystals or oily liquid Density: 1.493 g/cm3[2] 1.22 g/cm3 (50 wt% aq. solution) Melting point: 26.5 °C (79.7 °F; 299.6 K) Boiling point: 130 °C (266 °F; 403 K) decomposes Solubility in water: miscible Solubility: very soluble in alcohol, ether Acidity (pKa): 1.2 Conjugate base: Phosphinate Boiling point: 108 °C (1013 hPa) (decomposition) Density: 1.21 g/cm3 (20 °C) Melting Point: <-25 °C pH value: 1 (H₂O, 20 °C) Vapor pressure: 30 hPa (20 °C) vapor pressure: <17 mmHg ( 20 °C) Quality Level: 200 form: liquid concentration: 48-52% in NaOH (titration) 50 wt. % in H2O pH: 1 (20 °C, 500 g/L) density: 1.206 g/mL at 25 °C SMILES string: O[PH2]=O InChI: 1S/H3O2P/c1-3-2/h3H2,(H,1,2) InChI key: ACVYVLVWPXVTIT-UHFFFAOYSA-N Boiling Point/Range: 108 °C.Decomposes on heating. Color: Colorless Concentration: 50.00% Corrosivity: Corrosive to metals Density: 1.210 - 1.260 g/cm3 (20 °C) Flashpoint: Not applicable Form: Liquid Grade: Reagent Grade Incompatible Materials: Oxidizing agents. Bases. Corrosive in contact with metals. Decomposes by reaction with alkaline solutions. Lower Explosion Limit: Not applicable Melting Point/Range: < -25 °C Partition Coefficient: no data available Purity Percentage: 50.00 Purity Details: ~50.00% Solubility in Water: completely miscible Upper Explosion Limit: Not applicable Vapor Pressure: 30 hPa (20 °C) Viscosity: no data available pH-Value: 1.0 (20 °C) Product Line: Puriss. p.a. Storage Temperature: Ambient Molecular Weight: 65.996 g/mol XLogP3-AA: -1.1 Hydrogen Bond Donor Count: 1 Hydrogen Bond Acceptor Count: 2 Rotatable Bond Count: 0 Exact Mass: 65.98706633 g/mol Monoisotopic Mass: 65.98706633 g/mol Topological Polar Surface Area: 37.3Ų Heavy Atom Count: 3 Complexity: 10.3 Isotope Atom Count: 0 Defined Atom Stereocenter Count: 0 Undefined Atom Stereocenter Count: 0 Defined Bond Stereocenter Count: 0 Undefined Bond Stereocenter Count: 0 Covalently-Bonded Unit Count: 1 Compound Is Canonicalized: Yes Specifications of Hypophosphorous acid: Property: Value Assay: 48.5 - 51.4 % Density (D 20/4): 1.208 - 1.220 Arsenic (As): Max. 0.5 ppm Barium (Ba): Max. 50 ppm Calcium (Ca): Max. 50 ppm Cadmium (Cd): Max. 1 ppm Cobalt (Co): Max. 1 ppm Chromium (Cr): Max. 1 ppm Copper (Cu): Max. 1 ppm Iron (Fe): Max. 10 ppm Potassium (K): Max. 10 ppm Magnesium (Mg): Max. 10 ppm Manganese (Mn): Max. 1 ppm Sodium (Na): Max. 2000 ppm Nickel (Ni): Max. 1 ppm Lead (Pb): Max. 1 ppm Zinc (Zn): Max. 1 ppm Chloride (Cl): Max. 200 ppm Total S (as SO4): Max. 200 ppm Phosphate, phosphite (as H3PO4): Max. 1 % Assay (alkalimetric): ≥ 49.5 % Phosphorous acid and phosphoric acid (as H₃PO₃): ≤ 2 Chloride (Cl): ≤ 0.015 % Total sulfur (as SO₄): ≤ 0.02 % As (Arsenic): ≤ 0.0005 % Ba (Barium): ≤ 0.005 % Ca (Calcium): ≤ 0.005 % Cd (Cadmium): ≤ 0.0001 % Cu (Copper): ≤ 0.0005 % Fe (Iron): ≤ 0.005 % K (Potassium): ≤ 0.001 % Mn (Manganese): ≤ 0.0005 % Na (Sodium): ≤ 0.10 % Ni (Nickel): ≤ 0.0005 % Pb (Lead): ≤ 0.0005 % Zn (Zinc): ≤ 0.0001 % Structure of Hypophosphorous acid: Molecular shape: pseudo-tetrahedral Related compounds of Hypophosphorous acid: Sodium hypophosphite Barium hypophosphite Related phosphorus oxoacids: Phosphorous acid Phosphoric acid Names of Hypophosphorous acid: Regulatory process names: Hypophosphorous acid hypophosphorous acid Hypophosphorous acid (VAN) Hypophosphorus acid Phosphine oxide, hydroxy- Phosphinic acid Phosphinic acid phosphinic acid Phosphonous acid (VAN) IUPAC names: hydroxy-oxophosphanium HYPOPHOSPHOROUS ACID Hypophosphorous acid hypophosphorous acid Hypophosphorous acid Hypophosphorus Acid phosphenous acid Phosphinic acid phosphinic acid Phospinic Acid Unterphosphorige Säure Phosphinic acid Trade names: Hypophosphorous acid Hypophosphorous acid 50 % Other names: Hydroxy(oxo)-λ5-phosphane Hydroxy-λ5-phosphanone Oxo-λ5-phosphanol Oxo-λ5-phosphinous acid Phosphonous acid (for minor tautomer) Other identifiers: 60062-19-3 6303-21-5