Aluminium phosphide

Properties

AlP crystals are dark grey to dark yellow in color and have a zincblende crystal structure with a lattice constant of 5.4510 Å at 300 K. They are thermodynamically stable up to 1000 C.

Aluminium phosphide reacts vigorously with water or acids to release phosphine. The phosphine is the basis of the toxicity of AlP.

Preparation

AlP is synthesized by combination of the elements:

:

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 and carbon dioxide (e.g. ammonium carbamate), which help 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. PestPhos, Quickphos, Celphos, Fostox, Fumitoxin, Phostek, Phostoxin, Talunex, Fieldphos, PH3, and Weevil-Cide. It generates phosphine gas according to the following hydrolysis equation:

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.

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).

Toxicology

Main article: Aluminium phosphide poisoning

Highly poisonous, aluminium phosphide has been used for suicide. Fumigation has also caused unintentional deaths. 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.

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 aluminium phosphide reacting with water or moisture, and becoming phosphine, leading to their death within hours.

Aluminium phosphide poisoning is considered a wide-scale problem in the Indian subcontinent.

Manufacturers

It is manufactured by UPL Corporation globally, Intech Organics in India, Scimplify in the USA and others.

Regulation

In the UK, a license and "appropriate training" are required to purchase it. As of 2010, it was still available over the counter in India though "stricter norms" according to one author had been adopted.

In the EU, it is an approved pesticide. The expiration of the approval was postponed twice, the last time on November 13, 2025.

References

References

1. Berger, L. I.. (1996). "Semiconductor Materials". CRC Press.
2. (1997). "Bravais Lattices; Zincblende Lattice". University of Colorado.
3. (2004). "Lattice Constants". SiliconFarEast.com.
4. {{Holleman&Wiberg
5. (2007). "Inorganic Syntheses".
6. (1944). "Aluminum Phosphide – Preparation and Composition". Journal of the American Chemical Society.
7. United States Environmental Protection Agency. (2006). ''Inert Reassessment-Ammonium Carbamate'' [Data File]. Retrieved from [https://web.archive.org/web/20080327065249/http://www.epa.gov/opprd001/inerts/carbamate.pdf]
8. Buckle, A.. "Rodenticides".
9. Corbridge, D. E. C.. (1995). "Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology". Elsevier.
10. (2002-10-10). "Millionaire's death sparks poison scare". [[BBC News]].
11. (2009-02-24). "Fumes kill two Danes in Jeddah". [[BBC News]].
12. (2010-02-09). "Family loses 2nd child in suspected pesticide poisoning". [[KSL-TV]].
13. (2017-01-02). "4 children dead in Texas in pesticide spraying incident". [[CBS News]].
14. Badshah, Nadeem. (2024-07-18). "Girl, 11, died on her birthday after London neighbour used bedbug poison". The Guardian.
15. (2009). "A Retrospective 7-Years Study of Aluminum Phosphide Poisoning in Tehran: Opportunities for Prevention". Human & Experimental Toxicology.
16. (2010). "Rice Tablet Poisoning: A Major Concern in Iranian Population". Human & Experimental Toxicology.
17. (3 February 2014). "La familia de Alcalá de Guadaira murió tras inhalar plaguicida". [[La Vanguardia]].
18. (1995). "The profile of acute poisonings in Harayana-Rohtak Study". The Journal of the Association of Physicians of India.
19. (1999). "Changing trends in acute poisoning in Chandigarh zone: A 25-year autopsy experience from a tertiary care hospital in northern India". The American Journal of Forensic Medicine and Pathology.
20. "Aluminium phosphide: general information".
21. (2010). "Management of celphos poisoning with a novel intervention: A ray of hope in the darkest of clouds". Anesthesia, Essays and Researches.
22. European Free Trade Association. "Factsheet - 32025D2279".