Aluminium phosphate

Aluminium phosphate

Names
Other names Aluminum phosphate Aluminium monophosphate Phosphoric acid, aluminium salt (1:1)
Identifiers
CAS Number	7784-30-7 Y 22784-12-9 (trihydrate)
3D model (Jmol)	Interactive image Interactive image
ChemSpider	58204 Y
ECHA InfoCard	100.029.142
PubChem CID	64655
RTECS number	TB6450000
UNII	F92V3S521O Y
InChI InChI=1S/Al.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+3;/p-3 Y Key: ILRRQNADMUWWFW-UHFFFAOYSA-K Y InChI=1/Al.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+3;/p-3/rAlO4P/c2-6-3-1(4-6)5-6 Key: ILRRQNADMUWWFW-ITXURHEJAW InChI=1/Al.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+3;/p-3 Key: ILRRQNADMUWWFW-DFZHHIFOAZ
SMILES O=P12O[Al](O1)O2 [Al+3].[O-]P([O-])([O-])=O
Properties
Chemical formula	AlPO4
Molar mass	121.9529 g/mol
Appearance	White, crystalline powder
Density	2.566 g/cm3, solid
Melting point	1,800 °C (3,270 °F; 2,070 K)
Boiling point	Decomposes
Solubility in water	insoluble
Solubility product (Ksp)	6.3×10−19
Solubility	Very slightly soluble in HCl and HNO3
Refractive index (nD)	1.546
Pharmacology
ATC code	A02AB03 (WHO)
Hazards
EU classification (DSD)	Xi
R-phrases	R36/37/38
S-phrases	S26
NFPA 704	0 2 0
Lethal dose or concentration (LD, LC):
LD50 (median dose)	4640 mg/kg (rat, oral) > 4640 mg/kg (rabbit, dermal)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Aluminium phosphate (AlPO₄) is a chemical compound. The anhydrous form is found in nature as the mineral berlinite. Many synthetic forms of anhydrous aluminium phosphate are known. They have framework structures similar to zeolites and some are used as catalysts or molecular sieves. The dihydrate, AlPO₄·2H₂O is found as the minerals variscite and meta-variscite. A synthetic hydrated form, AlPO₄·1.5H₂O is also known. Commercially, an aluminium phosphate gel is available.

AlPO₄ is isoelectronic with Si₂O₄, silicon dioxide. Berlinite looks like quartz and has a structure that is similar to quartz with silicon replaced by Al and P. The AlO₄ and PO₄ tetrahedra alternate. Like quartz, AlPO₄ exhibits chirality and piezoelectric properties. Crystalline AlPO₄ (berlinite) when heated, converts to tridymite and cristobalite forms, and this mirrors the behaviour of silicon dioxide.

The structure can be regarded as an assembly of phosphate anions, aluminium cations and water. The aluminium cations are six-coordinate.

There are many of aluminium phosphate molecular sieves, generically known as "ALPOs". The first ones were reported in 1982. They all share the same chemical composition of AlPO₄ and have framework structures with microporous cavities. The frameworks are made up of alternating AlO₄ and PO₄ tetrahedra. The denser cavity-less crystalline AlPO₄ mineral, berlinite, shares the same alternating AlO₄ and PO₄ tetrahedra. The aluminophosphate framework structures vary one from another in the orientation of the AlO₄ tetrahedra and PO₄ tetrahedra to form different-sized cavities, and in this respect they are similar to the aluminosilicate zeolites, which differ in having electrically charged frameworks. A typical preparation of an aluminophosphate involves the hydrothermal reaction of phosphoric acid and aluminium in the form of hydroxide, an aluminium salt such as aluminium nitrate salt or alkoxide under controlled pH in the presence of organic amines. These organic molecules act as templates (now termed structure directing agents, SDAs) to direct the growth of the porous framework.