Aluminium phosphide

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Not to be confused with Aluminium phosphate.
Aluminium phosphide
Aluminium phosphide
Names
Other names
Aluminum phosphide
Aluminium(III) phosphide
Aluminium monophosphide
Phostoxin
Fumitoxin
Identifiers
20859-73-8 YesY
ChemSpider 28171 YesY
EC Number 244-088-0
Jmol 3D model Interactive image
PubChem 30332
RTECS number BD1400000
UNII E23DR6L59S YesY
  • InChI=1S/Al.P YesY
    Key: PPNXXZIBFHTHDM-UHFFFAOYSA-N YesY
  • InChI=1/Al.P/rAlP/c1-2
    Key: PPNXXZIBFHTHDM-LQQCNYPFAR
  • [Al]#P
Properties
AlP
Molar mass 57.9552 g/mol
Appearance Yellow or gray crystals
Odor garlic-like
Density 2.85 g/cm3
Melting point 2,530 °C (4,590 °F; 2,800 K)
reacts
Band gap 2.5 eV (indirect)[1]
2.75 (IR), ~3 (Vis) [1]
Structure
Zincblende
T2d-F43m
a = 546.35 pm
Tetrahedral
Thermochemistry
47.3 J/mol K
-164.4 kJ/mol
Vapor pressure {{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Aluminium phosphide (aluminum phosphide) is a highly toxic inorganic compound with the chemical formula AlP used as a wide band gap semiconductor and a fumigant. This colorless solid is generally sold as a grey-green-yellow powder due to the presence of impurities arising from hydrolysis and oxidation.

Properties

AlP crystals are dark grey to dark yellow in color and have a zincblende crystal structure[2] with a lattice constant of 5.4510 Å at 300 K.[3] They are thermodynamically stable up to 1,000 °C (1,830 °F).[4]

Aluminium phosphide reacts with water or acids to release phosphine:[5]

AlP + 3 H2O → Al(OH)3 + PH3
AlP + 3 H+ → Al3+ + PH3

Preparation

AlP is synthesized by combination of the elements:[4][6]

4Al + P4 → 4AlP

Caution must be taken to avoid exposing the AlP to any sources of moisture, as this generates toxic phosphine gas.

Uses

Pesticide

AlP is used as a rodenticide, insecticide, and fumigant for stored cereal grains. It is used to kill small verminous mammals such as moles and rodents. The tablets or pellets, known as "wheat pills", typically also contain other chemicals that evolve ammonia which helps to reduce the potential for spontaneous ignition or explosion of the phosphine gas.

AlP is used as both a fumigant and an oral pesticide. As a rodenticide, aluminium phosphide pellets are provided as a mixture with food for consumption by the rodents. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic phosphine gas. Other pesticides similar to aluminium phosphide are zinc phosphide and calcium phosphide. In this application, aluminium phosphide can be encountered under various brand names, e.g. Celphos, Fumitoxin, Phostoxin, Talunex and Quick Phos. It generates phosphine gas according to the following hydrolysis equation.[6]

2 AlP + 6 H2O → Al2O3∙3 H2O + 2 PH3

It is used as a fumigant when other pesticide applications are impractical and when structures and installations are being treated, such as in ships, aircraft, and grain silos. All of these structures can be effectively sealed or enclosed in a gastight membrane, thereby containing and concentrating the phosphine fumes. Fumigants are also applied directly to rodent burrows.[7]

Semiconductor applications

Industrially, AlP is a semiconductor material that is usually alloyed with other binary materials for applications in devices such as light-emitting diodes (e.g. aluminium gallium indium phosphide).[8]

Toxicology

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Main article: Aluminium phosphide poisoning

Evidently poisonous, aluminium phosphide has been used for suicide.[9] Fumigation has also caused unintentional deaths, such as examples in Saudi Arabia[10] and the United States.[11] Known as "rice tablet" in Iran, for its use to preserve rice, there have been frequent incidents of accidental or intentional death. There is a campaign by the Iranian Forensic Medicine Organization to stop its use as a pesticide.[12][13]

Recycling of used aluminium phosphide containers caused the death of three family members in Alcalá de Guadaira, Spain. They had been keeping them in plastic sacks in their bathroom. The deaths occurred accidentally due to aluminum phosphide reacting with water or moisture, and becoming phosphine, leading to their death within hours.[14]

Aluminium phosphide poisoning is considered a wide-scale problem in the Indian subcontinent.[15][16]

References

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  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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