Hypophosphorous acid Chemische Eigenschaften,Einsatz,Produktion Methoden
R-Sätze Betriebsanweisung:
R34:Verursacht Verätzungen.
S-Sätze Betriebsanweisung:
S26:Bei Berührung mit den Augen sofort gründlich mit Wasser abspülen und Arzt konsultieren.
S36/37/39:Bei der Arbeit geeignete Schutzkleidung,Schutzhandschuhe und Schutzbrille/Gesichtsschutz tragen.
S45:Bei Unfall oder Unwohlsein sofort Arzt zuziehen (wenn möglich, dieses Etikett vorzeigen).
Aussehen Eigenschaften
H3PO2; Hypophosphorige Säure, Phosphinsäure, Phosphor(I)-säure. Farblose Flüssigkeit ohne Geruch.
Gefahren für Mensch und Umwelt
Verursacht Verätzungen. Schädigt vor allem die Augen bei Kontakt.
Zersetzung oberhalb 130鳦 unter Freisetzung von Phosphan. Nicht mit Metallen in Berührung bringen. Weitere gefährliche Zersetzungsprodukte sind Phosphin und Phosphorsäure.
Schutzmaßnahmen und Verhaltensregeln
Schutzhandschuhe als kurzzeitiger Spritzschutz.
Verhalten im Gefahrfall
Mit flüssigkeitsbindendem Material, z.B. Rench Rapid aufnehmen. Der Entsorgung zuführen. Nachreinigen. Unschädlich machen mit verdünnter Natronlauge.
Auf Umgebung abstimmen.
Nicht brennbar.
Erste Hilfe
Nach Hautkontakt: Mit reichlich Wasser abwaschen. Abtupfen mit Polyethylenglycol 400.
Nach Augenkontakt: Mit reichlich Wasser bei geöffnetem Lidspalt mindestens 15 Minuten ausspülen. Sofort Augenarzt hinzuziehen.
Nach Einatmen: Frischluft. Arzt hinzuziehen.
Nach Verschlucken: Reichlich Wasser trinken. Erbrechen wegen Perforationsgefahr vermeiden. Sofort Arzt hinzuziehen.
Nach Kleidungskontakt: Kontaminierte Kleidung sofort entfernen.
Ersthelfer: siehe gesonderten Anschlag
Sachgerechte Entsorgung
Vorsichtig in Wasser eintragen, neutralisieren und ins Abwasser geben.
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).
Chemische Eigenschaften
colourless liquid
Physikalische Eigenschaften
Colorless deliquescent crystals or oily liquid; sour odor; density 1.493 g/cm3;melts at 26.5°C; boils at 130°C; very soluble in water, alcohol and ether; den-sity of a 50% aqueous solution is 1.13 g/mL.
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.
Vorbereitung Methode
Hypophosphorous acid is formed by reaction of barium hypophosphite and sulfuric acid, and filtering off barium sulfate. By evaporation of the solution in vacuum at 80 °C, and then cooling to 0°C, hypophosphorous acid crystallizes.
Definition
ChEBI: 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.
synthetische
Hypophosphorous acid may be prepared by various methods:
1. Boiling white phosphorus with calcium hydroxide:
P
4 + 4Ca(OH)
2 + 8H
2O → 4Ca(H2PO
2)
2 + 4H
2
The calcium salt is soluble in water. Treatment with sulfuric acid yields thehypophosphorous acid:
(H
2PO
2)2Ca + H
2SO
4 → 2H
3PO
2 + CaSO
4
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.
PH
3 + 2I
2 + 2H
2O → H
3PO
2 + 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.
Reaktionen
Hypophosphorous acid is miscible with water in all proportions and a commercial strength is 30% H3PO2. Hypophosphites are used in medicine. Hypophosphorous acid is a powerful reducing agent, e.g., with copper sulfate forms cuprous hydride Cu2H2, brown precipitate, which evolves hydrogen gas and leaves copper on warming; with silver nitrate yields finely divided silver; with sulfurous acid yields sulfur and some hydrogen sulfide; with sulfuric acid yields sulfurous acid, which reacts as above; forms manganous immediately with permanganate.
Allgemeine Beschreibung
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.
Air & Water Reaktionen
Deliquescent. Water soluble.
Reaktivität anzeigen
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.
Hazard
Fire and explosion risk in contact with oxidizing agents.
Health Hazard
TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
Brandgefahr
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.
läuterung methode
Phosphorous acid is a common contaminant of commercial 50% hypophosphorous acid. Jenkins and Jones [J Am Chem Soc 74 1353 1952] purified this material by evaporating about 600mL in a 1L flask at 40o, under reduced pressure (in N2), to a volume of about 300mL. After the solution was cooled, it was transferred to a wide-mouthed Erlenmeyer flask which was stoppered and left in a Dry-ice/acetone bath for several hours to freeze (if necessary, with scratching of the wall). When the flask was then left at ca 5o for 12hours, about 30-40% of it liquefied, and was again filtered. This process was repeated, then the solid was stored over Mg(ClO4)2 in a vacuum desiccator in the cold. Subsequent crystallisations from n-butanol by dissolving it at room temperature and then cooling in an ice-salt bath at -20o did not appear to purify it further. The free acid forms deliquescent crystals m 26.5o and is soluble in H2O and EtOH. The NaH2PO2 salt can be purified through an anion exchange resin [Klement Z Anorg Allgem Chem 260 267 1949.]
Hypophosphorous acid Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
