Aluminium phosphide

Aluminium phosphide

Names
IUPAC name Aluminium phosphide
Other names Aluminum phosphide Aluminium monophosphide Aluminium(III) phosphide Fumitoxin Phostoxin
Properties
Chemical formula	AlP
Molar mass	57.9552 g/mol
Appearance	Gray or yellow solid
Odor	Odorless (pure) Garlic-like (impure)
Density	2.85 g/cm3
Melting point	2,530 °C (4,590 °F; 2,800 K)
Solubility in water	Reacts
Solubility	Reacts with acids Insoluble in organic solvents
Thermochemistry
Std molar entropy (So298)	47.3 J·K−1·mol−1
Std enthalpy of formation (ΔfHo298)	-164.4 kJ/mol
Hazards
Safety data sheet	None
Flash point	800 °C (1,470 °F; 1,070 K)
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	11.5 mg/kg (rat, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Aluminium phosphide is a highly toxic inorganic compound with the chemical formula AlP used as a wide band gap semiconductor and more commonly as fumigant.

Properties

Chemical

Aluminium phosphide reacts with water to form phosphine gas.

AlP + 3 H₂O → Al(OH)₃ + PH₃

Compared to most phosphides, hydrolysis of AlP produces very little diphosphane, meaning it's less likely to self-ignite in air. This is why AlP is preferred as source of phosphine, compared to other phosphides, like calcium phosphide.

Physical

Aluminium phosphide is a gray-yellowish solid, which an unpleasant garlic-like odor, highly toxic. It reacts with water and acids, and it is not soluble in organic solvents.

Availability

Aluminium phosphide is sold by pesticide sellers as fumigant, though it's nearly impossible to be acquired by the average individual in most countries, due to its high risks. Even many companies that deal with pesticides cannot acquire it without a special authorization.

Preparation

Aluminium phoshpide can be prepared by reacting aluminium powder with elemental phosphorus.

Projects

• Preparation of phosphine (EXTREMELY DANGEROUS AND VERY HIGH RISK OF DEATH)
• Preparation of elemental phosphorus
• Silo fumigant (in industry)

Handling

Safety

Aluminium phosphide is extremely toxic and contact with water or acids will result in phosphine gas, which is highly toxic. As there's no known antidote to phosphine poisoning, extreme care must be taken when handling this compound.

Storage

Aluminium phosphide should be kept in its original container and only open when it's about to be used immediately. Ampouling is another possibility, though only for smaller amounts.

Disposal

Aluminium phosphide is difficult to neutralize safely, as hydrolysis or even minute amounts will release enough phosphine to cause immediate harm to the individuals in the vicinity of the substance.

Sodium hypochlorite aka bleach has been shown to be effective in neutralizing phosphides, by oxidizing them. It has been determined that it's more effective than other oxidizers, such as hydrogen peroxide, permanganates. Low concentration of hypochlorite has shown to be more effective at removing the phosphine gas generated by the hydrolysis.

References

Relevant Sciencemadness threads

• H3PO4 + Al = phosphine ?