Tripotassium phosphate

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Tripotassium phosphate
Tripotassium phosphate.png
Unit cell of the anhydrous tripotassium phosphate under standard conditions (low temperature modification).
Unit cell of tripotassium phosphate.
IUPAC name
Potassium phosphate
Systematic IUPAC name
Potassium tetraoxidophosphate(3−)
Other names
Potassium phosphate, tribasic
3D model (JSmol)
ECHA InfoCard 100.029.006
E number E340(iii) (antioxidants, ...)
Molar mass 212.27 g/mol
Appearance White deliquescent powder
Density 2.564 g/cm3 (17 °C)
Melting point 1,380 °C (2,520 °F; 1,650 K)
90 g/100 mL (20 °C)
Solubility in ethanol Insoluble
Basicity (pKb) 1.6
Primitive orthorhombic
Pnma, No. 62
a = 1.123772 nm, b = 0.810461 nm, c = 0.592271 nm[1]
Main hazards Irritant
Safety data sheet MSDS
R-phrases (outdated) R36-R38
S-phrases (outdated) S26-S36
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
Related compounds
Other cations
Trisodium phosphate
Triammonium phosphate
Tricalcium phosphate
Related compounds
Monopotassium phosphate
Dipotassium phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Tripotassium phosphate, also called potassium phosphate tribasic,[2] is a water-soluble salt which has the chemical formula K3PO4.(H2O)x (x = 0, 3, 7, 9)[3] Tripotassium phosphate is a strong base.


Tripotassium phosphate can be produced by the reaction of ammonium phosphate () with potassium chloride ().[4]

Use in organic chemistry[edit]

Tripotassium phosphate has few applications except as a basic reagent in organic synthesis. It has been used as a catalyst for certain organic reactions.


Tripotassium phosphate has been used a catalyst for many organic reactions. It is cost-effective and has been used as an efficient catalyst to replace more expensive alternatives. Some of the reactions catalysed by are listed below:

  1. Hydrated tripotassium phosphate () can be used as a catalyst for the removal of BOC protecting group from secondary BOC amines using methanol as a solvent. Microwave radiation is used to aid the reaction.[5]
  2. is used as a catalyst for the synthesis of unsymmetrical diaryl ethers using [Bmim] as the solvent. Aryl methane-sulfonates are deprotected and then followed by a nucleophilic aromatic substitution (SNAr) with activated aryl halides.[6]
  3. was found to be one of the catalysts that aids in the 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.[7]
  4. can be used as one of the catalysts for the addition of aryl halides to phenols and aliphatic alcohols.[8]


Tripotassium phosphate is strongly basic.


  1. ^ a b Voronin, V. I.; Ponosov, Yu. S.; Berger, I. F.; Proskurnina, N. V.; Zubkov, V. G.; Tyutyunnik, A. P.; Bushmeleva, S. N.; Balagurov, A. M.; Sheptyakov, D. V.; Burmakin, E. I.; Shekhtman, G. Sh.; Vovkotrub, E. G. (2006). "Crystal structure of the low-temperature form of K3PO4". Inorganic Materials. 42 (8): 908–913. doi:10.1134/S0020168506080206.
  2. ^ "Potassium phosphate tribasic P5629". Sigma-Aldrich. Retrieved 2018-04-27.
  3. ^ Klaus Schrödter; Gerhard Bettermann; Thomas Staffel; Friedrich Wahl; Thomas Klein; Thomas Hofmann (2012). "Phosphoric Acid and Phosphates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_465.pub3.
  4. ^ Cyclic process for producing tripotassium phosphate and ammonium chloride, 1968-10-15, retrieved 2018-04-27
  5. ^ Dandepally, Srinivasa Reddy; Williams, Alfred L. (2009-03-04). "Microwave-assisted N-Boc deprotection under mild basic conditions using K3PO4·H2O in MeOH". Tetrahedron Letters. 50 (9): 1071–1074. doi:10.1016/j.tetlet.2008.12.074. ISSN 0040-4039.
  6. ^ Xu, Hui; Chen, Yang (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. 12 (4): 861–867. doi:10.3390/12040861. PMC 6149384.
  7. ^ Shirakawa, Eiji; Kitabata, Takaaki; Otsuka, Hidehito; Tsuchimoto, Teruhisa (2005-10-10). "A simple catalyst system for the palladium-catalyzed coupling of aryl halides with terminal alkynes". Tetrahedron. 61 (41): 9878–9885. doi:10.1016/j.tet.2005.07.099. ISSN 0040-4020.
  8. ^ Niu, Jiajia; Zhou, Hua; Li, Zhigang; Xu, Jingwei; Hu, Shaojing (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. 73 (19): 7814–7817. doi:10.1021/jo801002c. ISSN 0022-3263. PMID 18771324.