|Jmol-3D images||Image 1|
|Molar mass||99.943 g/mol|
|Melting point||> 650 °C|
|Solubility in water||hydrolysis|
|Solubility||insoluble in liquid CO2|
a = 4.9512 Å
c = 8.7874 Å
|around P 5 near neighbours, trigonal bipyramid |
|Other anions||sodium chloride
|Other cations||aluminium phosphide
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Sodium phosphide, Na3P, is a black, ionic salt containing the alkali metal sodium and the phosphide anion. Na3P is a source of the highly reactive phosphide anion. It should not be confused with sodium phosphate, Na3PO4.
In addition to Na3P, five other binary compositions of sodium and phosphorus are known: NaP, Na3P7, Na3P11, NaP7, and NaP15.
Many different routes to Na3P have been described. Due to its flammability and toxicity, Na3P (and related salts) are generally prepared in situ. White phosphorus is reduced by sodium-potassium alloy to give the phosphide salt.
- P4 + 12 Na → 4 Na3P
Alternatively the reaction can be conducted at normal pressures but using a temperatures gradient to generate nonvolatile NaxP phases (x < 3) that then react further with sodium. In some cases, an electron-transfer agent, such as naphthalene, is used. In such applications, the naphthalene forms the soluble radical anions and more rapidly reduces the phosphorus.
Sodium phosphide is a source of the highly reactive phosphide anion. The material is insoluble in all solvents but reacts as a slurry with acids and related electrophiles to give derivatives of the type PM3:
- Na3P + 3 M+5 → M3P (M = H, Me3Si)
The trimethylsilyl derivative is volatile (b.p. 30-35 C @ 0.001 mm Hg) and soluble. It serves as a soluble equivalent to "P3-".
Indium phosphide, a semiconductor arises by treating in-situ generated "sodium phosphide" with indium(III) chloride in hot N,N’-dimethylformamide as solvent. In this process, the phosphide reagent is generated from sodium metal and white phosphorus, whereupon it immediately reacts with the indium salt:
- 3Na + P → Na3P
- Na3P + InCl3 → InP + 3NaCl
Sodium phosphide is also employed commercially as a catalyst in conjunction with zinc phosphide and aluminium phosphide for polymer production. When Na3P is removed from the ternary catalyst polymerization of propylene and 4-methyl-1-pentene is not effective.
Sodium phosphide is highly dangerous releasing toxic phosphine upon hydrolysis, a process that is so exothermic that fires result. The USDOT has forbidden the transportation of Na3P on passenger aircraft, cargo only aircraft, and trains due to the potential fire and toxic hazards.
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- Environmental Chemistry Chemical Database- safety information for sodium phosphide from the U.S. Code of Federal Regulations