HYPOPHOSPHOROUS ACID

HYPOPHOSPHOROUS ACID = Hypophosphorous acid = hydroxy(oxo)phosphanium = Phosphinic acid

CAS-No: 6303-21-5
EC-No: 228-601-5
MDL: MFCD02183592
Molecular Formula : H3O2P, H3PO2

Hypophosphorous acid appears as colorless oily liquid or deliquescent crystals with a sour odor. 
Phosphinic 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. 
The parent of the class of phosphinic acids. 
Hypophosphorous acid has a role as an antioxidant. 

Hypophosphorous acid is a phosphorus oxoacid and a member of phosphinic acids. 
Hypophosphorous acid is a conjugate acid of a phosphinate.
Free hypophosphorous acid, H3PO2, 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.
The pure Hypophosphorous acid cannot be isolated merely by evaporating the water, however, because of the easy oxidation of the hypophosphorous acid to phosphoric acids (and elemental phosphorus) and Hypophosphorous acids disproportionation to phosphine and phosphorous acid. 
The pure Hypophosphorous acid acid can be obtained by extraction of Hypophosphorous acids 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. 
Hypophosphorous acid (HPA), 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. 
The formula for Hypophosphorous acid is generally written H3PO2, but a more descriptive presentation is HOP(O)H2, which highlights Hypophosphorous acids 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 phosphinic acid
Hypophosphorous Acid (HPA) is also known as phosphinic acid, hydroxy(oxo)-λ5-phosphane, oxo-λ5-phosphinous acid and oxo-λ5-phosphanol. 
Hypophosphorous acids 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. Hypophosphorous acid is majorly manufactured from Sodium Hypophosphite.
Hypophosphorous acid (HPA) also known as phosphonic 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. 

The hypophosphorous acid formula which is the same for phosphinic acid formula is H3PO2 is a neutral molecule with no spare charge on Hypophosphorous acid. 
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. 
The parent of the class of phosphinic acids.

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 its official IUPAC name is phosphinic 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 its 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 phosphinic acid.
Hypophosphorous acid (H3PO2) is a colorless low-melting compound (m.p. 26.5 °C), which is a commercially available inorganic acid, and is usually supplied as a 50% aqueous solution. 

H3PO2 is a powerful reducing agent, and Hypophosphorous acids aqueous solution can be used under moderate conditions in contrast to some other strong reducing agents, which are normally applied in the absence of water (e.g., LiAlH4, DIBAL). 
Furthermore, Hypophosphorous acid is also an important hydrogen donor.
Hypophosphorous acid is a phosphorus oxoacid and a powerful reducing agent with molecular formula H3PO2. 
Inorganic chemists refer to the free acid by this name (also as "HPA"), or the acceptable name of phosphinic acid. 

Hypophosphorous acid is a colorless low-melting.
Hypophosphorous acid or phosphinic acid (H3PO2) is a monobasic acid having +1 oxidation state for phosphorus. 
Phosphorus is in +5 oxidation state in phosphoric acid, (H3PO4) which is a tribasic acid.
Hypophosphorous acid is a phosphorus oxoacid and a powerful reducing agent.

Uses and applications of Hypophosphorous acid:
-Hydrated sodium hypophosphite, NaH2PO2 · H2O, is used as an industrial reducing agent, particularly for the electroless plating of nickel onto metals and nonmetals.
-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. 
-Hypophosphorous Acid is used in various end use industries, such as building and construction, electronics and electrical, chemical and plastics, etc. 
-Hypophosphorous Acid is significantly used as a salt (sodium hypophosphite) and also in electroless nickel plating (Ni–P), as well as Hypophosphorous Acid is also used for reducing arenediazonium salts. 

-Pharmaceutical
-Reducing Agent
-Resin
-Ink
-Coating
-Bleaching agent
-Tetrabasic acid
-Wetting agent
-Stimulant in pharmaceutical agents
-Electroless Nickel Plating 
-Catalysts
-Cements
-Polymers
-Indirect food additives
-Adhesives and components of coatings

-H3PO2 participates as a reducing agent for the conversion of aromatic and aliphatic diselenides to the corresponding selenols.
-Hypophosphorous Acid is used to make hypophosphites and in electroplating baths.
-Hypophosphorous acid is used in the formulation of pharmaceuticals, discoloration of polymers, water treatment, retrieval of precious or non-ferrous metals. 
-Hypophosphorous Acids main use is for electroless plating; i.e. deposition of metal films from solution. 

-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.
-Beside the good reducing ability, e.g. in the reduction of diazonium salts, halide compounds, benzylic alcohols, etc., H3PO2 has been extensively used in a variety of functional group transformations.
-Hypophosphorous Acid 30% to 32% Resin Grade is primarily used as antioxidant, catalyst in polymerization and poly condensation, and wetting agent,discoloration of polymers, water treatment and retrieval of precious or non-ferrous metals. 

-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. 
-Phosphorus acid is used as a reducing agent and to produce phosphite salts.
-Hypophosphorous Acid is used in the formulation of pharmaceuticals, discoloration of polymers, water treatment, retrieval of precious or non-ferrous metals. 

-Hypophosphorous Acids main use is for electroless plating; i.e. deposition of select metal films from solution on a sensitized surface.
-Hypophosphorous Acid Resin Grade is used to reduce colour of Alkyd and Polyester resin.
-Hypophosphorous acid is used as a decolorizing or bleaching agent in plastics, chemicals and synthetic fibers. -Hypophosphorous acid is also used as a polycondensation and polymerization agent, reducing agent, an antioxidant and stimulant in pharmaceuticals, etc.

Why H3PO2 is called hypophosphorous acid?
Hypophosphorous acid (HPA), or phosphinic acid, is a phosphorus oxyacid and a powerful reducing agent with molecular formula H3PO2. 
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 phosphinic acid.

Why hypophosphorous acid is a good reducing agent?
Hypophosphorous acid as well as Hypophosphorous acids salts are strong reducing agents. 
Hypophosphorous acid has only one ionisable hydrogen atom i.e., the acid is monobasic. 
Hypophosphorous acid(H3PO2) has 1 acidic hydrogen(hydrogen attached to the electronegative atoms F,O,N), and hence has a tendency to release H+ ion making it reducing in nature.

How acidic is H3PO2?
If you see the structure of H3PO2 , then P is bonded to an oxygen with a double bond,2 hydrogens with single bonds and finally to a hydroxyl group. 
Acids are those compounds which can give free H+ ions . 
There are 3 hydrogens.

Physical and chemical properties of HYPOPHOSPHOROUS ACID:
Appearance Form: clear, liquid
Colour: colourless
Molecular Weight: 64.989 g/mol
Odour: No data available
Odour Threshold: No data available
pH: 1,0 at 500 g/l at 20 °C
Melting point: 26.5°C
Initial boiling point and boiling range: No data available
Flash point: No data available
Evaporation rate: No data available
Flammability (solid, gas): No data available
Upper/lower flammability or explosive limits: No data available
Vapour density: No data available
Relative density: 1,206 g/cm3 at 25 °C
Partition coefficient: n-octanol/water: No data available
Auto-ignition temperature: No data available
Decomposition temperature: No data available
Viscosity: 58.4 mN/m (60% aqueous solution)
Explosive properties: No data available
Oxidizing properties: No data available
Density: 1.439 g / cm3. 
Exact Mass: 64.97924130
Decomposes upon heating: >133 °C
Solubility: 
Miscible with water
Miscible with alcohol
Vapor Pressure: 0.00323 mmg Hg at 25 °C (effusion method: vapor pressure balance)
log Kow: -1.72 (est)
pKa: 2.27 at 22 °C
Boiling point: 108 °C (1013 hPa) (decomposition)

Phosphinic acid is prepared industrially via a two step process: 
Firstly, elemental phosphorus reacts with alkali and alkaline earth hydroxides to give an aqueous solution of hypophosphites.
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.
HPA is usually supplied as a 50% aqueous solution. 
Anhydrous acid cannot be obtained by simple evaporation of the water, as the acid ready 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.

Exposure controls/personal protection of HYPOPHOSPHOROUS ACID:
-Control parameters:
Components with workplace control parameters
-Exposure controls:
Personal protective equipment:
Skin protection:
Handle with gloves. 
Gloves must be inspected prior to use. 
Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact  with this product. 
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. 
Wash and dry hands.
Wear appropriate protective gloves to prevent skin exposure.
Full contact
Material: Nitrile rubber
Minimum layer thickness: 0,11 mm
Break through time: 480 min
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0,11 mm
Break through time: 480 min

Eyes protection: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166.

Clothing protection: 
Wear appropriate protective clothing to prevent skin exposure.
Face shield and splash goggles. 
Impervious neoprene or rubber gloves, apron, coveralls, and/or other resistant protective clothing. 
Sufficient to protect skin. 
A OSHA/MSHA jointly approved respirator is advised in the absence of proper environmental controls. 
For emergency situations, a self-contained respirator is recommended (NIOSH-approved). 
Do not wear contact lenses. 
Make eye bath and emergency shower available. 
Ensure that eyewash station and safety shower is proximal to the work-station location.

Engineering controls: 
Use in a chemical fume hood. 
Use adequate ventilation. 
Do not use in unventilated spaces.

First aid measures of HYPOPHOSPHOROUS ACID:
-Description of first aid measures: No data available
-Most important symptoms and effects, both acute and delayed:
-Indication of any immediate medical attention and special treatment needed: No data available

Eyes: 
Immediately flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. 
Immediate first aid is needed to prevent eye damage. 
Washing within 1 minute is essential to achieve maximum effectiveness. 
IMMEDIATELY flush eyes with copious quantities of water for at least 15 minutes holding lids apart to ensure flushing of the entire surface. 
Seek immediate medical attention.

Skin: 
Get medical aid immediately. 
Immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes.
Wash contaminated clothing before reusing. Discard contaminated leather articles such as shoes and belt.

Ingestion: 
Do not induce vomiting. 
Get medical aid immediately.
If conscious, wash out mouth with water. 
Have conscious person drink several glasses of water or milk. 
DO NOT induce vomiting. 
Seek immediate medical attention. 
Never give anything by mouth to an unconscious or convulsing person. 
If spontaneous vomiting occurs, have victim lean forward with head down to avoid breathing in of vomitus, rinse mouth and
administer more water. 

Inhalation: 
Get medical aid immediately. 
Remove from exposure and move to fresh air immediately. 
If breathing is difficult, give oxygen. 
Do not use mouth-to-mouth resuscitation if victim ingested or inhaled the substance; induce artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device.

Firefighting measures of Phosphinic acid:
-Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Unsuitable extinguishing media:
For this substance/mixture no limitations of extinguishing agents are given.
-Special hazards arising from the substance or mixture:
Oxides of phosphorus.
Not combustible.
-Advice for firefighters: No data available
-Further information: No data available

Accidental release measures of Phosphinic acid:
-Personal precautions, protective equipment and emergency procedures:
-Environmental precautions: No data available
-Methods and materials for containment and cleaning up: No data available

Handling and storage of Phosphinic acid:
-Precautions for safe handling:
-Conditions for safe storage, including any incompatibilities: No data available
Handling: 
Do not get in eyes, on skin, or on clothing. 
Do not ingest or inhale. 
Use only in a chemical fume hood.
Handle and open container with care.

Storage: 
Store in a cool, dry place. 
Store in a tightly closed container. 
Store in a cool place away from heated areas, sparks, and flame. 
Store in a well ventilated area. 
Store away from incompatible materials. 
Do not add any other material to the container. 
Do not wash down the drain. 
Do not breathe gas/fumes/vapor/spray. 
In case of insufficient ventilation, wear suitable respiratory equipment. 
Keep away from direct sunlight or strong incandescent light. 
Keep container tightly closed and dry. 
Manipulate under an adequate fume hood. 
Do not use pressure to dispense.  
Take off immediately all contaminated clothing. 
This product must be manipulated by qualified personnel. 
Do not get in eyes, on skin, or on clothing. 
Wash well after use. 
In accordance with good storage and handling practices. 
Do not allow smoking and food consumption while handling.

Stability and reactivity of Phosphinic acid:
Reactivity: No data available
Chemical stability: No data available
Possibility of hazardous reactions: No data available
Conditions to avoid: No data available
Incompatible materials: Strong oxidizing agents, Strong bases

Synonyms : 
Hydroxy(oxo)phosphanium
Acid, Phosphinic
Acids, Hypophosphorous
Acids, Phosphinic
Hypophosphorous Acids
Phosphinic Acid
Phosphinic Acids
Phosphine oxide, hydroxy-
Hydroxy-oxophosphanium
Hydroxy-oxo-phosphonium
Hydroxy-oxophosphonium
Hydroxy-keto-phosphonium
Hydroxy-oxo-phosphanium
Phosphinate