Boron phosphate

Boron phosphate is an inorganic compound with the chemical formula BPO₄. The simplest way of producing it is the reaction of phosphoric acid and boric acid. It is a white infusible solid that evaporates above 1450 °C.^[3]

Boron phosphate

Names
IUPAC name Boron phosphate
Systematic IUPAC name 2,4,5-trioxa-1λ5-phospha-3-borabicyclo[1.1.1]pentane 1-oxide[1]
Identifiers
CAS Number	13308-51-5
3D model (JSmol)	Interactive image
ChemSpider	75189
ECHA InfoCard	100.033.020
PubChem CID	83329
CompTox Dashboard (EPA)	DTXSID10872553
InChI InChI=1S/B.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+3;/p-3 Key: YZYDPPZYDIRSJT-UHFFFAOYSA-K InChI=1/B.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+3;/p-3 Key: YZYDPPZYDIRSJT-DFZHHIFOAS
SMILES B12OP(=O)(O1)O2
Properties
Chemical formula	BPO4
Molar mass	105.78 g/mol
Density	2.52 g/cm3
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302
Precautionary statements	P264, P270, P301+P312, P330, P501
NFPA 704 (fire diamond)	[2] 2 0 0
Safety data sheet (SDS)	External SDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis

Boron phosphate is synthesized from phosphoric acid and boric acid at a temperature range from 80 °C to 1200 °C. The relatively cold treatment produces a white amorphous powder, which is converted to a microcrystalline product when heated at about 1000 °C for 2 hours.^[4]

The main reaction of the process is:

H₃BO₃ + H₃PO₄ → BPO₄ + 3 H₂O

New ways of synthesizing the compound have also been reported, such as hydrothermal and microwave synthesis.^[5]

Due to the particular industrial interest of boron phosphate, other methods are used as well:^[5]

• Phosphoric acid and triethyl borate
• Triethyl phosphate and boron trichloride
• Diammonium phosphate acid and borax heated to 1000 °C
• Boric acid and phosphorus pentoxide (hydrothermal)

Structure

If obtained at pressure, the ordinary structure is isomorphous with the β-cristobalite, while subjecting it to high pressure is obtained a compound isomorphic with α-quartz.^[6] The structure of AlPO₄, berlinite, is isomorphous with α-quartz.^[3]

Applications

It is used as a catalyst for dehydration and other reactions in organic synthesis. Also, it serves as a source of phosphates for exchange reactions in the solid state to obtain metal phosphates.^[7]