Sodium hypophosphite

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Sodium hypophosphite
Names
IUPAC name
Sodium phosphinate
Other names
Sodium phosphenite
Properties
NaPO2H2 (anhydrous)
NaPO2H2·H2O (monohydrate)
Molar mass 87.98 g/mol (anhydrous)
105.99 g/mol (monohydrate)
Appearance Deliquescent white solid
Odor Odorless
Density 1.77 g/cm3 (monohydrate)
Melting point 310 °C (590 °F; 583 K) (monohydrate) (decomposes)
Boiling point Decomposes
90 g/100 ml (20 °C)
Solubility Slightly soluble in aq. ammonia, ethanol, ethylene glycol, methanol
Poorly soluble in propylene glycol
Solubility in ethylene glycol 33.0 g/100 g (25 °C)[1]
Solubility in propylene glycol 9.7 g/100 g (25 °C)[2]
Vapor pressure ~0 mmHg
Hazards
Safety data sheet Sigma-Aldrich (monohydrate)
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
7,640 mg/kg (rat, oral)
Related compounds
Related compounds
Hypophosphorous acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sodium hypophosphite or sodium phosphinate is the sodium salt of hypophosphorous acid with the formula NaPO2H2. It is often encountered as the monohydrate, NaPO2H2·H2O.

Properties

Chemical

Sodium hypophosphite decomposes into phosphine which is highly irritating to the respiratory tract and disodium phosphate.

2 NaPO2H2 → PH3 + Na2HPO4

Sodium hypophosphite has been indicated to react explosively when triturated with chlorates.[3]

Physical

Sodium hypophosphite is a colorless hygroscopic solid, soluble in water.

Availability

Sodium hypophosphite is sold by chemical suppliers.

Sodium hypophosphite, like its parent compound hypophosphorous acid, is listed as List I precursor chemical in the United States, as it can reduce elemental iodine to form hydroiodic acid, which is a reagent effective for reducing ephedrine or pseudoephedrine to methamphetamine. Due to this restriction, the compound cannot be freely acquired by the hobby chemist in the United States.

Preparation

Careful addition of white phosphorus to a hot aqueous solution of sodium hydroxide yields sodium hypophosphite.

P4 + 4 NaOH + 4 H2O → 4 NaPO2H2 + 2 H2

Phosphine is produced as side product. Since this gas is very toxic, this reaction must be done outside, away from houses or in a special fumehood, one that can remove harmful gaseous products.

Projects

Handling

Safety

Sodium hypophosphite is irritant and should be handled with care.

Storage

Sodium hypophosphite should be kept in a cool, dry place, isolated from oxidizing materials.

Disposal

Can be neutralized by dissolving it in water and then an oxidizer, such as hydrogen peroxide is added, which converts it to phosphate.

References

  1. O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Cambridge, UK: Royal Society of Chemistry, 2013., p. 1601
  2. O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Cambridge, UK: Royal Society of Chemistry, 2013., p. 1601
  3. O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Cambridge, UK: Royal Society of Chemistry, 2013., p. 1601

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