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Aluminium phosphate
Names
	Other names Aluminum phosphate; Aluminium monophosphate; Phosphoric acid, aluminium salt (1:1)
Identifiers
CAS Number	7784-30-7 ; 22784-12-9 (trihydrate);
3D model (JSmol)	Interactive image; Interactive image;
ChEMBL	ChEMBL3833315;
ChemSpider	58204 ;
DrugBank	DB14517;
ECHA InfoCard	100.029.142
EC Number	232-056-9;
PubChem CID	64655;
RTECS number	TB6450000;
UNII	F92V3S521O ;
UN number	1760
CompTox Dashboard (EPA)	DTXSID5064839;
	InChI InChI=1S/Al.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+3;/p-3 Key: ILRRQNADMUWWFW-UHFFFAOYSA-K ; 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	1.89×10−9 g/100 ml
Solubility product (Ksp)	9.84×10−21
Solubility	Very slightly soluble in HCl and HNO3
Refractive index (nD)	1.546
Pharmacology
ATC code	A02AB03 (WHO)
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H314, H315, H319, H332, H335
Precautionary statements	P260, P261, P264, P271, P280, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P321, P332+P313, P337+P313, P362, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)	2 0 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). verify (what is ?) Infobox references

Aluminium phosphate is a chemical compound. In nature it occurs as the mineral berlinite.^[3] Many synthetic forms of aluminium phosphate are known. They have framework structures similar to zeolites and some are used as catalysts, ion-exchangers or molecular sieves.^[4] Commercial aluminium phosphate gel is available.

Berlinite

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^[5] and piezoelectric properties.^[6] When heated, crystalline AlPO₄ (berlinite) converts to tridymite and cristobalite forms, and this mirrors the behaviour of silicon dioxide.^[7]

Uses

Molecular sieves

There are many types of aluminium phosphate molecular sieves, generically known as "ALPOs". The first ones were reported in 1982.^[8] 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 berlinite, shares the same alternating AlO₄ and PO₄ tetrahedra.^[7] 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.^[9] These organic molecules act as templates (now termed structure directing agents, SDAs) to direct the growth of the porous framework.^[10]

Other

Along with aluminium hydroxide, aluminium phosphate is one of the most common immunologic adjuvants (efficiency enhancers) in vaccinations. Aluminium adjuvant use is widespread due to its cheap price, long history of use, safety and efficiency with most antigens.

Similar to aluminium hydroxide, AlPO₄ is used as an antacid. It neutralizes stomach acid (HCl) by forming AlCl₃ with it. Up to 20% of aluminium from ingested antacid salts can be absorbed from the gastrointestinal tract – despite some unverified concerns about the neurological effects of aluminium,^[11] aluminium phosphate and hydroxide salts are thought to be safe as antacids in normal use, even during pregnancy and breastfeeding.^[12]^[11]

Additional uses for AlPO₄ in combination with or without other compounds are white colorants for pigments, corrosion inhibitors, cements and dental cements. Related compounds have also similar uses. For example, Al(H₂PO₄)₃ is used in dental cements, metal coatings, glaze compositions and refractory binders; and Al(H₂PO₄)(HPO₄) is used cement and refractory binders and adhesives.^[13]

Related compounds

AlPO₄·2H₂O dihydrate is found as the minerals variscite and meta-variscite.^[14] Aluminium phosphate dihydrate (variscite and meta-variscite) has a structure that can be regarded as an assembly of tetra- and octahedral units of phosphate anions, aluminium cations and water. Al³⁺ ions are 6-coordinate and PO₄^3- ions are 4-coordinate.^[3]

A synthetic hydrated form, AlPO₄·1.5H₂O is also known.^[15]

References

DEC, Corbridge. (2013). Phosphorus: chemistry, biochemistry and technology (6th ed.). CRC Press. ISBN 9781439840894.

Citations

^ ^a ^b John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 4–47. ISBN 978-1138561632.
^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
^ ^a ^b Corbridge, p. 207-208
^ Corbridge, p. 310
^ Tanaka, Y; et al. (2010). "Determination of structural chirality of berlinite and quartz using resonant x-ray diffraction with circularly polarized x-rays". Physical Review B. 81 (14): 144104. Bibcode:2010PhRvB..81n4104T. doi:10.1103/PhysRevB.81.144104. ISSN 1098-0121.
^ Crystal growth of an α-quartz like piezoelectric material, berlinite, Motchany A. I., Chvanski P. P., Annales de Chimie Science des Materiaux properties, 2001, 26, 199
^ ^a ^b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 527. ISBN 978-0-08-037941-8.
^ Wilson, ST; et al. (1982). "Aluminophosphate molecular sieves: a new class of microporous crystalline inorganic solids". Journal of the American Chemical Society. 104 (4): 1146–1147. doi:10.1021/ja00368a062. ISSN 0002-7863.
^ Kulprathipanja, S, ed. (2010-02-17). Zeolites in Industrial Separation and Catalysis. John Wiley & Sons. doi:10.1002/9783527629565. ISBN 9783527325054.
^ Xu, R; et al. (2007). Chemistry of zeolites and related porous materials: synthesis and structure. John Wiley & Sons. p. 39. ISBN 9780470822333.
^ ^a ^b Schaefer, Christof; Peters, Paul W. J.; Miller, Richard K. (2015). Drugs during pregnancy and lactation: treatment options and risk assessment. C Schaefer, P Peters, RK Miller (3. ed.). Elsevier Science. p. 94. ISBN 9780124080782.
^ S, Pratiksha; TM, Jamie (2018), "Antacids", StatPearls, StatPearls Publishing, PMID 30252305, retrieved 2019-02-28
^ Corbridge, p. 1025
^ Roncal-Herrero, T; et al. (2009-12-02). "Precipitation of Iron and Aluminum Phosphates Directly from Aqueous Solution as a Function of Temperature from 50 to 200 °C". Crystal Growth & Design. 9 (12): 5197–5205. CiteSeerX 10.1.1.722.3917. doi:10.1021/cg900654m. ISSN 1528-7483.
^ Lagno, F; et al. (2005). "Synthesis of Hydrated Aluminium Phosphate, AlPO₄·1.5H₂O (AlPO4−H3), by Controlled Reactive Crystallization in Sulfate Media". Industrial & Engineering Chemistry Research. 44 (21): 8033–8038. doi:10.1021/ie0505559. ISSN 0888-5885.