PHOSPHONIC ACID (PHOSPHOROUS ACID)

Phosphonic Acid (Phosphorous Acid) is an inorganic phosphorus oxyacid commonly represented by the formula H3PO3 and known for its strong reducing behavior compared with phosphoric acid.
Phosphonic Acid (Phosphorous Acid) is widely used as a chemical intermediate, water-treatment ingredient, and formulation aid in industrial processes where metal control, scale inhibition support, and redox performance are needed.
Phosphonic Acid (Phosphorous Acid) is valued for high water solubility, reliable acidity, and utility in producing phosphonate-based additives and specialty salts.

CAS Number: 13598-36-2
EC Number: 237-066-7
Molecular Formula: H3PO3
Molecular Weight: 82.00 g/mol

Synonyms: Phosphonic Acid, Phosphorous Acid, Phosphorous(III) Acid, Orthophosphorous Acid, Phosphorous Acid Solution, Phosphonic Acid (H3PO3), Phosphite Acid, Trihydrogen Phosphite, Hydrogen Phosphite, Phosphite (Acid Form), Phosphonic Acid Reagent Grade, Phosphorous Acid Technical Grade, Phosphonic Acid, Phosphorous Acid, H₃PO₃, Orthophosphorous Acid, Hydroxyphosphinic Acid, Hydrogen Phosphonate, Phosphonate Acid, Phosphonous Acid, Phosphinic Acid (context), Phosphorus(III) Acid, Phosphorus Acid, Phosphorous Acid Reagent, Phosphonic Acid Technical Grade, Phosphonic Acid Industrial Grade, Phosphonic Acid Chemical Grade, Phosphonic Acid Specialty Grade, Phosphorous Acid Reducing Agent, Phosphonic Acid Reducing Agent, Phosphorous Acid Water Treatment Intermediate, Phosphonic Acid Water Treatment Intermediate, Phosphorous Acid Metal Treatment Agent, Phosphonic Acid Metal Treatment Agent, Phosphorous Acid Metal Surface Agent, Phosphonic Acid Metal Surface Agent, Phosphorous Acid Corrosion Chemistry Precursor, Phosphonic Acid Corrosion Chemistry Precursor, Phosphorous Acid Catalysis Intermediate, Phosphonic Acid Catalysis Intermediate, Phosphorous Acid Chemical Intermediate, Phosphonic Acid Chemical Intermediate, Phosphorous Acid Agrochemical Intermediate, Phosphonic Acid Agrochemical Intermediate, Phosphorous Acid Fertilizer Intermediate, Phosphonic Acid Fertilizer Intermediate, Phosphorous Acid Chelating Precursor, Phosphonic Acid Chelating Precursor, Phosphorous Acid Complexing Precursor, Phosphonic Acid Complexing Precursor, Phosphorous Acid Organic Synthesis Intermediate, Phosphonic Acid Organic Synthesis Intermediate, Phosphorous Acid Polymer Processing Intermediate, Phosphonic Acid Polymer Processing Intermediate, Phosphorous Acid Surfactant Intermediate, Phosphonic Acid Surfactant Intermediate, Phosphorous Acid Detergent Intermediate, Phosphonic Acid Detergent Intermediate, Phosphorous Acid Water Treatment Additive, Phosphonic Acid Water Treatment Additive, Phosphorous Acid Antiscalant Precursor, Phosphonic Acid Antiscalant Precursor, Phosphorous Acid Industrial Reductant, Phosphonic Acid Industrial Reductant, Phosphorous Acid Stabilizing Agent (context), Phosphonic Acid Stabilizing Agent (context), Phosphorous Acid Functional Additive (context), Phosphonic Acid Functional Additive (context), Phosphorous Acid Fine Chemical, Phosphonic Acid Fine Chemical, Phosphorous Acid Specialty Chemical, Phosphonic Acid Specialty Chemical, Phosphorous Acid Raw Material, Phosphonic Acid Raw Material, Phosphorous Acid Feedstock, Phosphonic Acid Feedstock, Phosphorous Acid Bulk Chemical, Phosphonic Acid Bulk Chemical

APPLICATIONS

Phosphonic Acid (Phosphorous Acid) is used as a precursor for producing phosphonate-based scale inhibitors in water-treatment chemistry.
Phosphonic Acid (Phosphorous Acid) is applied in cooling-water programs as a building block for performance additives that manage hardness ions.
Phosphonic Acid (Phosphorous Acid) is incorporated into blends designed to reduce scale deposition on heat-exchanger surfaces.

Phosphonic Acid (Phosphorous Acid) is used in boiler-water formulations where controlled acidity and metal-ion management are important.
Phosphonic Acid (Phosphorous Acid) is applied to help reduce precipitation tendencies of calcium and magnesium salts in aqueous systems.
Phosphonic Acid (Phosphorous Acid) is used in industrial water circuits to support corrosion and deposit control strategies.

Phosphonic Acid (Phosphorous Acid) is used as a chemical intermediate in manufacturing phosphite salts such as sodium phosphite and potassium phosphite.
Phosphonic Acid (Phosphorous Acid) is used to produce metal phosphites that serve as specialty additives in multiple industries.
Phosphonic Acid (Phosphorous Acid) is used to synthesize organophosphonates via downstream chemical conversion routes.

Phosphonic Acid (Phosphorous Acid) is used in polymer processing as a reducing and stabilizing component in selected formulations.
Phosphonic Acid (Phosphorous Acid) is applied in resin systems where control of oxidation state can improve product consistency.
Phosphonic Acid (Phosphorous Acid) is used in specialty plastics formulations to support long-term stability under processing conditions.

Phosphonic Acid (Phosphorous Acid) is used in electroplating and metal-finishing baths as a functional acid component in selected systems.
Phosphonic Acid (Phosphorous Acid) is applied to help control metal-ion behavior and bath stability in certain surface-treatment processes.
Phosphonic Acid (Phosphorous Acid) is used in metal cleaning and pickling formulations where reducing properties are beneficial.

Phosphonic Acid (Phosphorous Acid) is used as a reducing agent in chemical synthesis where mild, controllable reduction is required.
Phosphonic Acid (Phosphorous Acid) is used to reduce and stabilize reactive intermediates in industrial reaction sequences.
Phosphonic Acid (Phosphorous Acid) is applied in processes where oxidation suppression improves yield or color stability.

Phosphonic Acid (Phosphorous Acid) is used in textile and fiber processing to help stabilize certain dye and auxiliary systems.
Phosphonic Acid (Phosphorous Acid) is applied in process-water conditioning for textile operations with high mineral loads.
Phosphonic Acid (Phosphorous Acid) is incorporated into formulations to reduce scale-related defects in wet processing.

Phosphonic Acid (Phosphorous Acid) is used in paper and pulp operations to manage metal ions that can interfere with bleaching chemistry.
Phosphonic Acid (Phosphorous Acid) is applied in process-water circuits to reduce deposit formation on machine surfaces.
Phosphonic Acid (Phosphorous Acid) is used in cleaning-in-place systems to support removal of mineral residues.

Phosphonic Acid (Phosphorous Acid) is used in detergent and cleaning formulations as an acidic builder component in selected industrial cleaners.
Phosphonic Acid (Phosphorous Acid) is applied in descaling products to improve performance against carbonate and oxide deposits.
Phosphonic Acid (Phosphorous Acid) is incorporated into formulations intended for hard-water environments to improve cleaning reliability.

Phosphonic Acid (Phosphorous Acid) is used in agriculture chemistry as a precursor to phosphite salts used in certain nutrient and treatment products.
Phosphonic Acid (Phosphorous Acid) is used to manufacture potassium phosphite solutions for agricultural formulation markets.
Phosphonic Acid (Phosphorous Acid) is applied where phosphite chemistry is selected for its solubility and formulation flexibility.

Phosphonic Acid (Phosphorous Acid) is used in chemical manufacturing as a controlled-acidity reagent for pH adjustment in specialized processes.
Phosphonic Acid (Phosphorous Acid) is incorporated into formulations where buffering behavior and ionic strength control are required.
Phosphonic Acid (Phosphorous Acid) is used where strong water solubility supports uniform distribution in aqueous blends.

Phosphonic Acid (Phosphorous Acid) is used in cosmetics and personal care manufacturing primarily as a processing chemical in non-finished-product contexts.
Phosphonic Acid (Phosphorous Acid) is applied in equipment cleaning protocols to remove mineral build-up from stainless steel processing lines.
Phosphonic Acid (Phosphorous Acid) is used in industrial hygiene programs where scale control improves operational efficiency.

Phosphonic Acid (Phosphorous Acid) is used in chemical polishing and metal-surface preparation steps prior to coating.
Phosphonic Acid (Phosphorous Acid) is applied to improve surface uniformity in certain pretreatment sequences.
Phosphonic Acid (Phosphorous Acid) is used where controlled reduction helps limit undesirable oxide formation.

Phosphonic Acid (Phosphorous Acid) is used in laboratory settings as a reagent for inorganic and organophosphorus synthesis.
Phosphonic Acid (Phosphorous Acid) is used in analytical chemistry as a reducing acid in selected test methods.
Phosphonic Acid (Phosphorous Acid) is applied in research formulations requiring soluble phosphorus(III) chemistry.

Phosphonic Acid (Phosphorous Acid) is used in specialty catalyst preparation where reduction state influences catalyst behavior.
Phosphonic Acid (Phosphorous Acid) is used in catalyst regeneration processes where reduction of oxidized species is desired.
Phosphonic Acid (Phosphorous Acid) is applied in controlled redox environments to stabilize sensitive metal centers.

Phosphonic Acid (Phosphorous Acid) is used in water-treatment concentrate manufacturing due to compatibility with many inorganic salts.
Phosphonic Acid (Phosphorous Acid) is incorporated into multi-component blends where consistent acidity improves product reproducibility.
Phosphonic Acid (Phosphorous Acid) is used where deposit control programs require reliable performance across pH ranges.

Phosphonic Acid (Phosphorous Acid) is used in industrial formulations that require a non-volatile, water-soluble acid source.
Phosphonic Acid (Phosphorous Acid) is applied where low odor and strong solubility support safer handling compared with some alternatives.
Phosphonic Acid (Phosphorous Acid) is selected when a reducing acid is preferred over purely non-reducing mineral acids.

Phosphonic Acid (Phosphorous Acid) is used to produce phosphite esters that serve as stabilizers in polymer and lubricant markets.
Phosphonic Acid (Phosphorous Acid) is used in intermediate production where phosphorus-containing performance additives are required.
Phosphonic Acid (Phosphorous Acid) is applied in value chains that supply corrosion inhibitors, antiscalants, and process aids.

Phosphonic Acid (Phosphorous Acid) is used in specialty metalworking-fluid packages where deposit control improves tool-life consistency.
Phosphonic Acid (Phosphorous Acid) is incorporated into formulations that must manage hardness ions in recirculating systems.
Phosphonic Acid (Phosphorous Acid) is used where controlled acidity improves stability of formulated concentrates.

Phosphonic Acid (Phosphorous Acid) is used in cleaning formulations for food-industry equipment when compatible with regulatory and process requirements.
Phosphonic Acid (Phosphorous Acid) is applied in beverage and dairy plant sanitation systems primarily for mineral deposit removal steps.
Phosphonic Acid (Phosphorous Acid) is used where mineral scale reduction supports hygiene and operational uptime.

Phosphonic Acid (Phosphorous Acid) is used in industrial chemical blends where performance depends on maintaining metals in solution.
Phosphonic Acid (Phosphorous Acid) is applied where precipitation control reduces fouling, plugging, and downtime.
Phosphonic Acid (Phosphorous Acid) is valued in many sectors due to multifunctionality as a soluble acid and reducing reagent.

Phosphonic Acid (Phosphorous Acid) is used as a precursor in the synthesis of phosphite salts.
Phosphonic Acid (Phosphorous Acid) is used to produce potassium phosphite fertilizers.
Phosphonic Acid (Phosphorous Acid) enhances nutrient delivery in specialty agricultural fertilizers.

Phosphonic Acid (Phosphorous Acid) is used in foliar nutritional products.
Phosphonic Acid (Phosphorous Acid) improves phosphorus availability under soil stress conditions.
Phosphonic Acid (Phosphorous Acid) supports plant root development in micronutrient formulations.

Phosphonic Acid (Phosphorous Acid) is used in fungicidal agricultural applications.
Phosphonic Acid (Phosphorous Acid) provides systemic control of downy mildew in horticultural crops.
Phosphonic Acid (Phosphorous Acid) is used to reduce plant disease pressure in vineyards and orchards.

Phosphonic Acid (Phosphorous Acid) is used in industrial water treatment.
Phosphonic Acid (Phosphorous Acid) is used in scale inhibitor formulations for cooling towers.
Phosphonic Acid (Phosphorous Acid) helps prevent precipitation of calcium carbonate in recirculating water.

Phosphonic Acid (Phosphorous Acid) is used in corrosion control packages.
Phosphonic Acid (Phosphorous Acid) enhances metal protection in boiler feedwater systems.
Phosphonic Acid (Phosphorous Acid) reduces corrosion rates in heat exchange equipment.

Phosphonic Acid (Phosphorous Acid) is used as a reducing agent in chemical synthesis.
Phosphonic Acid (Phosphorous Acid) reduces metal ions in catalytic reactions.
Phosphonic Acid (Phosphorous Acid) supports synthesis of organic intermediates.

Phosphonic Acid (Phosphorous Acid) is used in detergent and cleaning product formulations.
Phosphonic Acid (Phosphorous Acid) enhances chelation of metal ions in household cleaners.
Phosphonic Acid (Phosphorous Acid) helps prevent redeposition of soils during washing.

Phosphonic Acid (Phosphorous Acid) is used in oilfield chemical applications.
Phosphonic Acid (Phosphorous Acid) helps control mineral scale in downhole systems.
Phosphonic Acid (Phosphorous Acid) enhances operational reliability in drilling water systems.

Phosphonic Acid (Phosphorous Acid) is used in electroplating and metal finishing.
Phosphonic Acid (Phosphorous Acid) improves bath stability in nickel and zinc plating processes.
Phosphonic Acid (Phosphorous Acid) reduces undesired precipitation during metal deposition.

Phosphonic Acid (Phosphorous Acid) is used in paper and pulp processing.
Phosphonic Acid (Phosphorous Acid) prevents scale accumulation in paper mill evaporators.
Phosphonic Acid (Phosphorous Acid) enhances heat transfer efficiency in mill equipment.

Phosphonic Acid (Phosphorous Acid) is used in textile auxiliaries.
Phosphonic Acid (Phosphorous Acid) improves dyeing consistency by sequestering hardness ions.
Phosphonic Acid (Phosphorous Acid) prevents formation of insoluble deposits during textile finishing.

Phosphonic Acid (Phosphorous Acid) is used in polymer stabilizer systems.
Phosphonic Acid (Phosphorous Acid) provides antioxidant support in polyolefin stabilization.
Phosphonic Acid (Phosphorous Acid) helps extend polymer life under oxidative stress.

Phosphonic Acid (Phosphorous Acid) is used in flame retardant additive systems.
Phosphonic Acid (Phosphorous Acid) contributes to char formation and smoke reduction.
Phosphonic Acid (Phosphorous Acid) supports halogen-free flame retardant strategies.

Phosphonic Acid (Phosphorous Acid) is used in laboratory analytical chemistry.
Phosphonic Acid (Phosphorous Acid) is used as a reducing reagent in phosphite synthesis.
Phosphonic Acid (Phosphorous Acid) assists in preparation of hypophosphite derivatives.

DESCRIPTION

Phosphonic Acid (Phosphorous Acid) is typically a white to off-white crystalline solid with little to no odor.
Phosphonic Acid (Phosphorous Acid) is highly soluble in water and forms acidic aqueous solutions.
Phosphonic Acid (Phosphorous Acid) is distinct from phosphoric acid because it contains phosphorus in a lower oxidation state and shows reducing character.

Phosphonic Acid (Phosphorous Acid) can form phosphite salts through neutralization with bases such as sodium hydroxide or potassium hydroxide.
Phosphonic Acid (Phosphorous Acid) is used as a practical source of phosphite chemistry in industrial and laboratory synthesis.
Phosphonic Acid (Phosphorous Acid) can participate in redox reactions that help suppress oxidation-related discoloration in certain processes.

Phosphonic Acid (Phosphorous Acid) is generally stable in sealed containers under normal storage conditions but should be protected from moisture and contaminants.
Phosphonic Acid (Phosphorous Acid) is corrosive in concentrated form and can cause irritation or burns on contact with skin or eyes.

Phosphonic Acid (Phosphorous Acid) should be handled with appropriate industrial hygiene practices due to its acidity and potential for irritation.
Phosphonic Acid (Phosphorous Acid) is an inorganic phosphorus oxyacid with the formula H₃PO₃.
Phosphonic Acid (Phosphorous Acid) is commonly referred to as phosphorous acid or phosphite acid.
Phosphonic Acid (Phosphorous Acid) typically appears as white crystalline material or a colorless aqueous solution.

Phosphonic Acid (Phosphorous Acid) is highly soluble in water and alcohols.
Phosphonic Acid (Phosphorous Acid) exhibits strong reducing properties.
Phosphonic Acid (Phosphorous Acid) is a key intermediate in the production of phosphite salts.

Phosphonic Acid (Phosphorous Acid) is distinct from phosphoric acid in oxidation state and reactivity.
Phosphonic Acid (Phosphorous Acid) contains phosphorus in the +3 oxidation state.
Phosphonic Acid (Phosphorous Acid) undergoes disproportionation under elevated temperatures.

Phosphonic Acid (Phosphorous Acid) participates in redox reactions involving metal ions.
Phosphonic Acid (Phosphorous Acid) must be handled in corrosion-resistant equipment.
Phosphonic Acid (Phosphorous Acid) should be stored in tightly sealed containers to prevent oxidation.

Phosphonic Acid (Phosphorous Acid) is valued for its role in agriculture, water treatment, and synthesis.
Phosphonic Acid (Phosphorous Acid) remains widely used due to its versatile chemical reactivity.
Phosphonic Acid (Phosphorous Acid) continues to play a central role in modern phosphorus chemistry.

PROPERTIES

Chemical Formula: H3PO3
Molecular Weight: 82.00 g/mol
Common Name: Phosphonic Acid (Phosphorous Acid)
Chemical Nature: Inorganic phosphorus oxyacid (phosphorus(III) acid)
Appearance: White to off-white crystalline solid
Odor: Odorless to faint characteristic
Solubility: Very soluble in water; soluble in polar solvents (grade dependent)
pH (1% aqueous): Strongly acidic (typical; concentration dependent)
Melting Point: ~70–75°C (may decompose; grade dependent)
Density: ~1.6–1.7 g/cm³ (typical; grade dependent)
Reducing Character: Reducing acid relative to phosphoric acid
Stability: Stable when dry and sealed; avoid strong oxidizers and excessive heat
Storage Temperature: 15–30°C, dry, tightly sealed
Shelf Life: 12–24 months in original packaging (typical supplier range)

FIRST AID

Inhalation:
Move to fresh air if dust or aerosols are inhaled.
Seek medical attention if coughing, shortness of breath, or throat irritation persists.
Avoid further exposure and keep the person warm and at rest.

Skin Contact:
Remove contaminated clothing and rinse skin with plenty of water.
Wash with soap and water after thorough rinsing.
Seek medical advice if irritation, redness, or burning sensation persists.

Eye Contact:
Rinse cautiously with water for several minutes.
Remove contact lenses if present and easy to do, then continue rinsing.
Seek immediate medical attention if pain, redness, or visual disturbance occurs.

Ingestion:
Rinse mouth with water and do not induce vomiting.
Give small amounts of water if the person is conscious and not convulsing.
Seek medical attention, especially if a significant amount is swallowed.

Note to Physicians:
Treat symptomatically and supportively.
Consider the corrosive nature of concentrated acid exposure.
Monitor for irritation or burns depending on exposure route.

HANDLING AND STORAGE

Handling:
Use appropriate PPE including chemical-resistant gloves, safety goggles, and protective clothing.
Avoid generating dust and avoid inhalation of dust or mists.
Do not eat, drink, or smoke while handling Phosphonic Acid (Phosphorous Acid).

Ventilation:
Use local exhaust or general ventilation in areas where dust or aerosols may be generated.
Provide adequate ventilation during dissolution, mixing, or transfer operations.
Minimize airborne exposure by using closed handling systems when possible.

Storage:
Store in a cool, dry place in tightly sealed, corrosion-resistant containers.
Protect from moisture uptake and keep away from incompatible materials such as strong oxidizers and strong bases.
Keep containers properly labeled and secured to prevent accidental contact.

Spill and Leak Procedures:
Avoid dust generation and wear appropriate PPE during cleanup.
Contain the spill and collect material using methods that minimize dust, then place into suitable containers.
Neutralize residues carefully if permitted by site procedures and dispose according to local regulations.

Handling Precautions:
Use corrosion-resistant equipment and avoid contact with reactive metals when solutions are strongly acidic.
Add Phosphonic Acid (Phosphorous Acid) to water slowly when preparing solutions to control heat and splashing.
Rotate stock using FIFO practices to maintain consistent quality and performance.