Monomagnesium phosphate

{{Chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 428780591

| Reference = [http://www.fao.org/ag/agn/jecfa-additives/specs/monograph5/additive-507-m5.pdf Monomagnesium phosphate], FAO JECFA Monographs 5 (2008)

| ImageFile = Magnesium phosphate monobasic.png

| ImageSize =

| ImageAlt =

| IUPACName =

| OtherNames = Monomagnesium orthophosphate;
Magnesium dihydrogen phosphate;
Magnesium phosphate monobasic;
Magnesium biphosphate;
Acid magnesium phosphate

| Section1 = {{Chembox Identifiers

| CASNo_Ref = {{cascite|correct|??}}

| CASNo = 13092-66-5

| CASNo_Comment = (Anhydrous)

| CASNo1_Ref = {{cascite|correct|CAS}}

| CASNo1 = 15609-80-0

| CASNo1_Comment = (Dihydrate)

| CASNo2_Ref = {{cascite|correct|CAS}}

| CASNo2 = 15609-87-7

| CASNo2_Comment = (Tetrahydrate)

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = AA2L7VX59K

| UNII_Comment = (Anhydrous)

| UNII1_Ref = {{fdacite|correct|FDA}}

| UNII1 = H3992158BT

| UNII1_Comment = (Dihydrate)

| UNII2_Ref = {{fdacite|correct|FDA}}

| UNII2 = XG6J0SHI70

| UNII2_Comment = (Tetrahydrate)

| PubChem = 516950

| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}

| ChemSpiderID = 451008

| SMILES = OP(=O)(O)[O-].OP(=O)(O)[O-].[Mg+2]

| InChI = 1/Mg.2H3O4P/c;2*1-5(2,3)4/h;2*(H3,1,2,3,4)/q+2;;/p-2

| InChIKey = QQFLQYOOQVLGTQ-NUQVWONBAA

| StdInChI_Ref = {{stdinchicite|changed|chemspider}}

| StdInChI = 1S/Mg.2H3O4P/c;2*1-5(2,3)4/h;2*(H3,1,2,3,4)/q+2;;/p-2

| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

| StdInChIKey = QQFLQYOOQVLGTQ-UHFFFAOYSA-L}}

| Section2 = {{Chembox Properties

| Mg=1|H=4|P=2|O=8

| Appearance = White, odorless, crystalline powder

| Density =

| MeltingPt =

| BoilingPt =

| Solubility = }}

| Section3 = {{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt = }}

}}

Monomagnesium phosphate is one of the forms of magnesium phosphate. It is a magnesium acid salt of phosphoric acid with the chemical formula Mg(H₂PO₄)₂.
Di- and tetrahydrates are known also. It dissolves in water, forming phosphoric acid and depositing a solid precipitate of Mg(HPO₄)·3H₂O, dimagnesium phosphate.{{cite book|author1=Klaus Schrödter|author2=Gerhard Bettermann|author3=Thomas Staffel|author4=Friedrich Wahl|author5=Thomas Klein|author6=Thomas Hofmann|title=Ullmann's Encyclopedia of Industrial Chemistry|chapter=Phosphoric acid and phosphates|series=Ullmann’s Encyclopedia of Industrial Chemistry|year=2008|publisher=Wiley-VCH|place=Weinheim|doi=10.1002/14356007.a19_465.pub3|isbn=978-3527306732|s2cid=94458523 }}

As a food additive, it is used as an acidity regulator and has the E number E343.