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Phosphinic Acid
H3PO2 · PHOSPHINIC ACID · HYPOPHOSPHORUS ACID · HYPOPHOSPHORIC ACID · hypophosphorous · Hypophoaphoeous acid · Hypophosphorous acid 50% · HYPOPHOSPOROUS ACID
Identifikatoren & physikalische Daten
| CAS No. | 6303-21-5 |
|---|---|
| Summenformel | H3O2P |
| Durchschnittliche Molmasse | 65,996 g/mol |
| Monoisotopische Masse | 65,98706597 g/mol |
| SMILES | O=[PH2]O |
| InChIKey | ACVYVLVWPXVTIT-UHFFFAOYSA-N |
| PubChem CID | 4124402 |
| ChEMBL | CHEMBL2105054 |
| EC No. | 228-601-5 |
| DTXSID | DTXSID90873902 |
Chemische & physikalische Eigenschaften
| XLogP | -1,1 |
|---|---|
| Polarare Oberfläche (TPSA) | 37,3 |
| H-Brücken-Donoren | 1 |
| H-Brücken-Akzeptoren | 2 |
| Frei drehbare Bindungen | 0 |
| Schwere Atome | 3 |
| Formalladung | 0 |
| Komplexität | 10,3 |
| Stoffklassen | Toxic Gases & Vapors -> Acids, Inorganic |
| pH | pH = 0.71 at 37 °C (100 g/L solution)pKa1= 1.00(25℃) |
| Dichte | Marketed in aqueous solutions of varying concentrations, 50% (density 1.274), 30-32% (density 1.13), 10% (density 1.04)1.439 @25 °C1.206 g/mL at 20 °C(lit.) |
| Viscosity | 58.4 mN/m (60% aqueous solution) |
| Color/Form | Hygroscopic crystals or colorless oily liquidWater free acid forms deliquescent crystalssupercools to a colorless oily liquid |
| Löslichkeit | Miscible with waterMiscible with alcoholvery soluble in H2O, ethanol, ethyl ether |
| Siedepunkt | Decomposes upon heating >133 °C130 °C @760 [mm Hg]108 °C (759.8513 mmHg) |
| Decomposition | Hazardous decomposition products formed under fire conditions - Oxides of phosphorus. /Hypophosphorous acid solution/Dec by heat into /phosphoric acid/ and spontaneously flammable /phosphine/.When heated to decomposition it emits toxic fumes of /phosphorous oxides/. |
| Schmelzpunkt | 26.5 °C-25 °C |
| Dampfdruck | 0.00323 mmg Hg at 25 °C (effusion method: vapor pressure balance)<17 mmHg ( 20 °C) |
| Food Contact Substances | FCS -> FDA Cumulative Estimated Daily Intake (CEDI) |
| Physical Description | Hypophosphorous acid appears as colorless oily liquid or deliquescent crystals with a sour odor. Density 1.439 g / cm3. Melting point 26.5 °C. Inhalation of vapors irritates or burns the respiratory tract. Liquid and vapors may irritate or burn eyes and skin.Deliquescent solid (from the water-free acid)Supercools to colorless odorless liquidmp = 26.5 deg C[Merck Index] Colorless odorless solution[MSDSonline] |
| Lagerbedingungen | no restrictions. |
| pKa (Säurekonstante) | pK1 1.1. |
| Aggregatzustand | hygroscopic crystals or colorless oily liquid |
| Farbe | Colorless |
| Merck | 13,4894 |
| Stabilität | Stable. Incompatible with strong bases. Reacts violently with oxidizing agents, strong bases, mercury (II) nitrate and mercury (II) oxide. Do not heat above 100 C. |
| InChI | 1S/H3O2P/c1-3-2/h3H2,(H,1,2) |
| InChIKey | GQZXNSPRSGFJLY-UHFFFAOYSA-N |
| SMILES | O[PH2]=O |
| CAS Datenbank | 6303-21-5(CAS DataBase Reference) |
| NIST chemische Informationen | Hypophosphorous acid(6303-21-5) |
| EPA chemische Informationen | Phosphinic acid (6303-21-5) |
Sicherheit & Vorschriften
| GHS-Einstufung | This chemical does not meet GHS hazard criteria for 1.5% (16 of 1039) of reports.DangerH290 (35.4%): May be corrosive to metals [Warning Corrosive to Metals]P234, P260, P264, P264+P265, P280, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P317, P321, P363, P390, P405, P406, and P501 (click each P-code to see the statement)Aggregated GHS information provided per 1039 reports by companies from 13 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies. |
|---|---|
| Regulatorische Informationen | Chemical: Phosphinic acidList I Chemical: A chemical specified by regulation that, in addition to legitimate uses, is used in manufacturing a controlled substance in violation of the Act and is important to the manufacture of a controlled substance. (21 eCFR 1310.02)Phosphinic acid is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Phosphinic acid are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)Status: Active Update: 05-05-2022 https://echa.europa.eu/registration-dossier/-/registered-dossier/14343Hypophosphorous acid: Does not have an individual approval but may be used under an appropriate group standard |
| Weitere Sicherheitsinformationen | IMAP assessments - Phosphinic acid: Environment tier I assessment |
| DOT-Kennzeichnung | Corrosive |
| Brandgefahren | Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: |
| Gesundheitsgefahren | Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: |
| Gefahrenübersicht | A strong reducing agent[Merck Index] Fire and explosion hazard in contact with oxidizing agents[Hawley] A strong reducing agentMay cause irritation or burns to skin, eye, and respiratory tract[CAMEO] Corrosive to skin and eyes[eChemPortal: ERMA] A corrosive substance that can cause injury to the skin, eyes, and respiratory tractInhalation may cause chemical pneumonitis[MSDSonline] |
| FDA-Anforderungen | The following chemicals have been specifically designated by the Administrator of the Drug Enforcement Administration as the listed chemicals subject to the provisions of this part and parts 1309 and 1313 of this chapter. Each chemical has been assigned the DEA Chemical Code Number set forth opposite it. Hypophosphorous acid and its salts (Including ammonium hypophosphite, calcium hypophosphite, iron hypophosphite, potassium hypophosphite, manganese hypophosphite, magnesium hypophosphite and sodium hypophosphite) (DEA Code Number: 6797) are included on List 1 chemicals. |
| Reaktive Gruppe | Reducing Agents, Strong |
| Reactivity Alerts | Strong Reducing Agent |
| Reactivity Profile | HYPOPHOSPHOROUS ACID decomposes when heated into phosphoric acid and spontaneously flammable phosphine. Is oxidized by sulfuric acid with release of sulfur dioxide and sulfur. Reacts explosively with mercury(II) oxide [Mellor, 1940, Vol. 4, 778]. Reacts violently with mercury(II) nitrate [Mellor, 1940, Vol. 4, 993]. Neutralizes bases in exothermic reactions. |
| Air and Water Reactions | Deliquescent. Water soluble. |
| Hazard Classes and Categories | Met. Corr. 1 (35.4%) |
| Brandbekämpfung | Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: |
| Erste Hilfe | Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: |
| Brandbekämpfungsverfahren | Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide. /Hypophosphorous acid solution/Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary. /Hypophosphorous acid solution/If material on fire or involved in fire: Use water in flooding quantities as fog. Use "alcohol" foam, dry chemical or carbon dioxide. |
| Lagerbedingungen | Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage. /Hypophosphorous acid solution/ |
| Reinigungsverfahren | ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Environmental precautions: Do not let product enter drains. Methods and materials for containment and cleaning up: Soak up with inert absorbent material and dispose of as hazardous waste. Keep in suitable, closed containers for disposal. /Hypophosphorous acid solution/Environmental considerations - Land spill: Dig a pit, pond, lagoon, holding area to contain liquid or solid material. Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. Absorb bulk liquid with fly ash, cement powder, or commercial sorbents.Environmental considerations - Water spill: Use natural barriers or oil control booms to limit spill travel. Use natural deep water pockets, excavated lagoons, or sand bag barriers to trap material at bottom. Add ferric chloride (FeCl3). Use mechanical dredges or lifts to remove immobilized masses of pollutants and precipitates.Environmental considerations - Air spill: Apply water spray or mist to knock down vapors. Disperse vapors using fans or blowers. |
| Freisetung ohne Brand | Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: |
| Entsorgungsverfahren | SRP: Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air qualitypotential migration in air, soil or watereffects on animal, aquatic and plant lifeand conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.Product: Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material. Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubberContaminated packaging: Dispose of as unused product. /Hypophosphorous acid solution/ |
| Preventive Measures | ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Environmental precautions: Do not let product enter drains. /Hypophosphorous acid solution/Precautions for safe handling: Avoid inhalation of vapor or mist. /Hypophosphorous acid solution/Appropriate engineering controls: Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday. /Hypophosphorous acid solution/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. /Hypophosphorous acid solution/For more Preventive Measures (Complete) data for Hypophosphorous acid (6 total), please visit the HSDB record page. |
| Isolation and Evacuation | Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: |
| Protective Action Criteria (PAC) | 1.2 [mg/m3]13 [mg/m3]79 [mg/m3] |
| Personal Protective Equipment (PPE) | Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]:Eye/face protection: Tightly fitting safety goggles. Faceshield (8-inch minimum). Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU). /Hypophosphorous acid solution/Skin protection: Handle with gloves. /Hypophosphorous acid solution/Body Protection: Complete suit protecting against chemicals. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. /Hypophosphorous acid solution/Respiratory protection: Where risk assessment shows air-purifying respirators are appropriate use a full-face respirator with multipurpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. If the respirator is the sole means of protection, use a full-face supplied air respirator. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU). /Hypophosphorous acid solution/ |
| Umweltverhalten | TERRESTRIAL FATE: Based on a classification scheme(1), a measured Koc range of 3.7 to 15 for the analogous sodium hypophosphite (which dissociates into the hypophosphorus acid ion in water)(2) indicates that hypophosphorus acid is expected to have very high mobility in soil(SRC). The pKa of hypophosphorous acid is 2.27(3), indicating that this compound will exist almost entirely in ionized form in the environment(SRC). Since ionized forms do not volatilize, volatilization from moist soil is not expected to be an important fate process(SRC). Hypophosphorous acid is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 0.00323 mm Hg at 25 °C(3). Biodegradation data in soil were not available(SRC, 2017).AQUATIC FATE: Based on a classification scheme(1), a measured Koc range of 3.7 to 15 for the analogous sodium hypophosphite (which dissociates into the hypophosphorus acid ion in water)(2) indicates that hypophosphorus acid is not expected to adsorb to suspended solids and sediment(SRC). The pKa of hypophosphorous acid is 2.27(3), indicating that this compound will exist almost entirely in ionized form in the environment(SRC). Since ionized forms do not volatilize, volatilization from water surfaces is not expected to be an important fate process(SRC). According to a classification scheme(4), an estimated BCF of 3(SRC), from an estimated log Kow of -1.72(5) and a regression-derived equation(5), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data in water were not available(SRC, 2017). Based on hydrolysis results for sodium hypophosphite(2), hypophosphorus acid is stable to hydrolysis in water(3).ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), hypophosphorus acid, which has a vapor pressure of 0.00323 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase hypophosphorus acid may be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC)however, the half-life for this reaction in air can not be estimated appropriately with current estimation methods since hypophosphorus acid in an inorganic compound(3). Hypophosphorus acid is miscible in water(4), therefore, atmospheric hypophosphorus acid may dissolve in precipitation, cloud or fog water and be removed from air via wet deposition(SRC). |
| Unerwünschte Wirkungen | Dermatotoxin - Skin burns. |
| Toxizitätsübersicht | IDENTIFICATION AND USE: Hypophosphorous acid is used in preparation of hypophosphites, and in electroplating baths. HUMAN STUDIES: Hypophosphorous acid solution (50%) was corrosive in a standardized and quantitative in vitro corrosivity test. ANIMAL STUDIES: There are no data available. |
| Soil Adsorption/Mobility | Using OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method) and five different soil types, sodium hypophosphite had Koc values ranging from 3.7 to 15(1). Since sodium hypophosphite dissociates into hypophosphorus acid ions in water(1), the Koc results will also apply to hypophosphorus acid(2). According to a classification scheme(3), these Koc values suggests that hypophosphorous acid is expected to have very high mobility in soil. |
| Human Toxicity Excerpts | /ALTERNATIVE and IN VITRO TESTS/ The Corrositex assay is a standardized and quantitative in vitro corrosivity test. The potential corrosivity of the test item was assessed by measuring the time that is required for the test item to pass through a biobarrier membrane and produce a change in a Chemical Detection System (CDS). 4 vials of 50% Hypophosphorous acid solution used in the test. According to the results (average breakthrough point: 12 min 05 sec) the substance is considered to be corrosive. ... |
| Artificial Pollution Sources | Hypophosphorus acid's production and use in electroplating baths, in the preparation of hypophosphites(1) and as a bleaching agent, reducing agent and catalyst(2) may result in its release to the environment through various waste streams(SRC). Hypophosphorus acid is on the US DEA (Drug Enforcement Administration) list of special surveillance chemicals used in clandestine drug manufacture(3). |
| Environmental Bioconcentration | An estimated BCF of 3 was calculated in fish for hypophosphous acid(SRC), using an estimated log Kow of -1.72(1) and a regression-derived equation(1). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC). |
| Volatilization from Water/Soil | The pKa of hypophosphorous acid is 2.27(1), indicating that this compound will exist almost entirely in ionized form in the environment(SRC). Since ionized forms do not volatilize, volatilization from water surfaces or moist soil is not expected to be an important fate process(SRC). Hypophosphorous acid is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 0.00323 mm Hg at 25 °C(1). |
| Environmental Abiotic Degradation | Sodium hypophosphite dissociates into hypophosphorus acid ions in water(1). Using OECD Guideline 111 (Hydrolysis as a Function of pH), sodium hypophosphite showed very minor hydrolytic degradation at pH values of 4.0, 7.0 and 9.0 and 50 °C(1). The estimated hydrolysis half-life is greater than one year under representative environmental conditions at 25 °Ctherefore, sodium hypophosphite is considered to be hydrolytically stable(1). This should also apply to hypophosphorus acid(SRC). |
| Probable Routes of Human Exposure | According to the 2012 TSCA Inventory Update Reporting data, 2 reporting facilities estimate the number of persons reasonably likely to be exposed during the manufacturing, processing, or use of hypophosphorous acid in the United States may be as low as <10 workers and as high as 25-49 workers per plantthe data may be greatly underestimated due to confidential business information (CBI) or unknown values(1).NIOSH (NOES Survey 1981-1983) has statistically estimated that 14,405 workers (2,961 of these are female) were potentially exposed to hypophosphorous acid in the US(1). Occupational exposure to hypophosphorous acid may occur through inhalation and dermal contact with this compound at workplaces where hypophosphorous acid is produced or used(SRC). Exposure to the general population may be possible in the vicinity of its use as a reagent during illicit drug manufacture. Hypophosphorous acid is on the US DEA (Drug Enforcement Administration) list of special surveillance chemicals used in clandestine drug manufacture(2). |
| Environmental Fate/Exposure Summary | Hypophosphorus acid's production and use in electroplating baths, in the preparation of hypophosphites and as a bleaching agent, reducing agent and catalyst may result in its release to the environment through various waste streams. If released to air, a vapor pressure of 0.00323 mm Hg at 25 °C indicates hypophosphorus acid will exist solely as a vapor in the atmosphere. Vapor-phase hypophosphorus acid will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicalsthe half-life for this reaction in air can not be estimated appropriately with current estimation methods. Hypophosphorus acid is miscible in water, and therefore, may dissolve in precipitation, cloud or fog water and be removed from air via wet deposition. If released to soil, hypophosphorus acid is expected to have very high mobility based upon a measured Koc range of 3.7 to 15 for the analogous sodium hypochorite. The pKa of hypophosphorous acid is 2.27, indicating that this compound will exist almost entirely in ionized form in the environment. Since ionized forms do not volatilize, volatilization from moist soil is not expected to be an important fate process. Hypophosphorus acid is not expected to volatilize from dry soil surfaces based upon its vapor pressure. If released into water, hypophosphorus acid is not expected to adsorb to suspended solids and sediment based upon the Koc. Biodegradation data in water or soil were not available. Volatilization from water surfaces is not expected to be an important fate process since the compound ionizes in water. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Based on hydrolysis results for sodium hypophosphite, hypophosphorus acid is stable to hydrolysis in water. Occupational exposure to hypophosphorous acid may occur through inhalation and dermal contact with this compound at workplaces where hypophosphorous acid is produced or used. Exposure to the general population may be possible in the vicinity of its use as a reagent during illicit drug manufacture. Hypophosphorous acid is on the US DEA (Drug Enforcement Administration) list of special surveillance chemicals used in clandestine drug manufacture. (SRC) |
| Antidote and Emergency Treatment | /SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Phosphine and Related Compounds//SRP:/ Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . /Phosphine and Related Compounds//SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Phosphine and Related Compounds//SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Inorganic acids and related compounds/For more Antidote and Emergency Treatment (Complete) data for Hypophosphorous acid (6 total), please visit the HSDB record page. |
| Wassergefährdungsklasse (WGK) | 1 |
| TSCA-Inventar-Status | TSCA listed |
| UN-Transportnummer | UN 3264 8/PG 3 |
| Zollcode | 28111990 |
| RTECS-Nr. | SZ6400000 |
| R-Sätze (R) | 34 |
| Gefahrensymbole | C |
| Sicherheitshinweise (S) | 26-36/37/39-45 |
| Gefahrenklasse | 8Eye Dam. 1Met. Corr. 1Skin Corr. 1B |
| Verpackungsgruppe | II |
| Lagerklasse | 8B - Non-combustible corrosive hazardous materials |
| Gefahrstoffdaten | 6303-21-5(Hazardous Substances Data) |
Anwendungen & Verwendung
Beschreibung
Hypophosphorous acid is a powerful reducing agent with a molecular formula of H3PO2. Inorganic chemists refer to the free acid by this name although its IUPAC name is dihydridohydroxidooxidophosphorus, or the acceptable name of phosphinic acid. It 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 phosphinates (hypophosphites).
Verwenden
Hypophosphorous acid is primarily used for electroless nickel plating. It is involved in the reduction of arenediazonium salts. It acts as an additive in Fischer esterification reactions. Also, it serves as a neutralizing agent, antioxidant, catalyst in polymerization and poly condensation, and wetting agent. Further, it is used in the formulation of pharmaceuticals, discoloration of polymers, water treatment and retrieval of precious or non-ferrous metals. In addition to this, it is used as bleaching agents for plastics, synthetic fibers, decolorizing agent and for color stabilization during the manufacture of chemicals and several plastics.
Herstellung & Synthese
synthetische
Hypophosphorous acid may be prepared by various methods: 1. Boiling white phosphorus with calcium hydroxide: P4 + 4Ca(OH)2 + 8H2O → 4Ca(H2PO2)2 + 4H2 The calcium salt is soluble in water. Treatment with sulfuric acid yields thehypophosphorous acid: (H2PO2)2Ca + H2SO4 → 2H3PO2 + CaSO4 The product mixture is filtered to remove insoluble CaSO4. The aqueous solu-tion of hypophosphorous acid is concentrated under reduced pressure.Concentrated baryta water may be used instead of calcium hydroxide.2. By treating sodium hypophosphite, NaH2PO2with an ion-exchange resin.The sodium salt may be produced by boiling white phosphorus with a solutionof sodium hydroxide, a reaction similar to (1) above. PH3 + 2I2 + 2H2O → H3PO2 + 4HI The above method may be considered safer than that involving heating whitephosphorus with an alkali. Hypophosphorous acid must be stored below 50°C. It is sold commerciallyas an aqueous solution at various concentrations.