Tripotassium phosphate

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title: "Tripotassium phosphate" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["potassium-compounds", "phosphates", "food-emulsifiers", "e-number-additives", "inorganic-fertilizers", "deliquescent-materials"] topic_path: "general/potassium-compounds" source: "https://en.wikipedia.org/wiki/Tripotassium_phosphate" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| Watchedfields = changed | verifiedrevid = 442343633 | ImageFile = Tripotassium phosphate.png | ImageSize = 150px | ImageFile1 = Kaliumphosphat.png | ImageSize1 = 240px | ImageCaption1 = Unit cell of tripotassium phosphate. | ImageAlt1 = Unit cell of the anhydrous tripotassium phosphate under standard conditions (low temperature modification). | IUPACName = Potassium phosphate | SystematicName = Potassium tetraoxidophosphate(3−) | OtherNames = Potassium phosphate, tribasic |Section1={{Chembox Identifiers | CASNo = 7778-53-2 | CASNo_Ref = | ChemSpiderID_Ref = | ChemSpiderID = 56408 | ChEBI = 190301 | EC_number = 231-907-1 | PubChem = 62657 | UNII_Ref = | UNII = 16D59922JU | SMILES = [K+].[K+].[K+].[O-]P([O-])([O-])=O | StdInChI_Ref = | StdInChI = 1S/3K.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3*+1;/p-3 | StdInChIKey_Ref = | StdInChIKey = LWIHDJKSTIGBAC-UHFFFAOYSA-K |Section2={{Chembox Properties | Formula = K3PO4 | MolarMass = 212.27 g/mol | Appearance = White deliquescent powder | Density = 2.564 g/cm3 (17 °C) | MeltingPtC = 1380 | BoilingPt = | Solubility = 90 g/100 mL (20 °C) | SolubleOther = Insoluble | Solvent = ethanol | pKb = 1.6 |Section3={{Chembox Structure | Structure_ref = | CrystalStruct = Primitive orthorhombic | LattConst_a = 1.123772 nm | LattConst_b = 0.810461 nm | LattConst_c = 0.592271 nm | LattConst_ref = | SpaceGroup = Pnma, No. 62 |Section4={{Chembox Hazards | ExternalSDS = MSDS | MainHazards = Irritant | NFPA-H = 2 | NFPA-F = 0 | NFPA-R = 0 | NFPA-S = | Hazards_ref= | GHSPictograms = | GHSSignalWord = Warning | HPhrases = | PPhrases = | FlashPt = Non-flammable |Section8={{Chembox Related | OtherAnions = | OtherCations = Trisodium phosphate Triammonium phosphate Tricalcium phosphate | OtherCompounds = Monopotassium phosphate Dipotassium phosphate

Tripotassium phosphate, also called tribasic potassium phosphate is a water-soluble salt with the chemical formula K3PO4.(H2O)x (x = 0, 3, 7, 9). Tripotassium phosphate is basic: a 1% aqueous solution has a pH of 11.8.

Production

Tripotassium phosphate is produced by the neutralization of phosphoric acid with potassium hydroxide: :

Use in organic chemistry

::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/52/K3PO4.jpg" caption="'''K3PO4'''"] ::

Tripotassium phosphate has few industrial applications, however it is commonly used as a base in laboratory-scale organic chemistry. Being insoluble in organic solvents, it is an easily removed proton acceptor in organic synthesis. The anhydrous salt is especially basic. Some of the reactions are listed below:

  1. The hydrate () has been used to catalyze the deprotection of BOC amines. Microwave radiation is used to aid the reaction.
  2. As a catalyst for the synthesis of unsymmetrical diaryl ethers using [Bmim]BF4 as the solvent. Aryl methane-sulfonates are deprotected and then followed by a nucleophilic aromatic substitution (SNAr) with activated aryl halides.
  3. As a base in the cross-coupling reaction of aryl halides with terminal alkynes. It also plays a role in the deacetonation of 4-aryl-2-methylbut-3-yn-2-ol intermediates.
  4. As the base in the cross-coupling reaction between aryl halides and phenols or aliphatic alcohols.

Use in foods

Tripotassium phosphate can be used in foods as a buffering agent, emulsifying agent, and for nutrient fortification. It can serve as a sodium-free substitute for trisodium phosphate. The ingredient is most common in dry cereals but is also found in meat, sauces, and cheeses.

References

References

  1. (2006). "Crystal structure of the low-temperature form of K3PO4". Inorganic Materials.
  2. "Potassium phosphate".
  3. "Potassium phosphate tribasic P5629".
  4. (2012). "Phosphoric Acid and Phosphates".
  5. (2010). "Encyclopedia of Reagents for Organic Synthesis".
  6. (2009-03-04). "Microwave-assisted N-Boc deprotection under mild basic conditions using K3PO4·H2O in MeOH". Tetrahedron Letters.
  7. (2007-04-30). "C(aryl)-O Bond Formation from Aryl Methanesulfonates via Consecutive Deprotection and SNAr Reactions with Aryl Halides in an Ionic Liquid". Molecules.
  8. (2005-10-10). "A simple catalyst system for the palladium-catalyzed coupling of aryl halides with terminal alkynes". Tetrahedron.
  9. (2008-10-03). "An Efficient Ullmann-Type C−O Bond Formation Catalyzed by an Air-Stable Copper(I)−Bipyridyl Complex". The Journal of Organic Chemistry.
  10. Han, James. (2020-08-03). "What is Tripotassium Phosphate E340(iii) in Food and Functions in Cereals?".

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potassium-compoundsphosphatesfood-emulsifierse-number-additivesinorganic-fertilizersdeliquescent-materials