Tripotassium phosphate explained

Tripotassium phosphate, also called tribasic potassium phosphate[1] is a water-soluble salt with the chemical formula K3PO4.(H2O)x (x = 0, 3, 7, 9). Tripotassium phosphate is basic.

Production

Tripotassium phosphate is produced by the neutralization of phosphoric acid with potassium hydroxide:H3PO4 + 3KOH -> K3PO4 + 3H2O

Use in organic chemistry

Tripotassium phosphate has few industrial applications.

It is used as an inert, easily removed proton acceptor in organic synthesis. Some of the reactions are listed below:

  1. The hydrate (K3PO4\cdot H2O) has been used to catalyze the deprotection of BOC amines. Microwave radiation is used to aid the reaction.[2]
  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]
  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]
  4. As the base in the cross-coupling reaction between aryl halides and phenols or aliphatic alcohols.[5]

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.[6]

Hazards

It is somewhat basic: a 1% aqueous solution has a pH of 11.8.

Notes and References

  1. Web site: Potassium phosphate tribasic P5629. Sigma-Aldrich. 2018-04-27.
  2. 2009-03-04. Microwave-assisted N-Boc deprotection under mild basic conditions using K3PO4·H2O in MeOH. Tetrahedron Letters. en. 50. 9. 1071–1074. 10.1016/j.tetlet.2008.12.074. 0040-4039. Dandepally. Srinivasa Reddy. Williams. Alfred L..
  3. 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. en. 12. 4. 861–867. 10.3390/12040861. 17851438. 6149384. free.
  4. 2005-10-10. A simple catalyst system for the palladium-catalyzed coupling of aryl halides with terminal alkynes. Tetrahedron. en. 61. 41. 9878–9885. 10.1016/j.tet.2005.07.099. 0040-4020. Shirakawa. Eiji. Kitabata. Takaaki. Otsuka. Hidehito. Tsuchimoto. Teruhisa.
  5. 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. EN. 73. 19. 7814–7817. 10.1021/jo801002c. 18771324. 0022-3263.
  6. Web site: Han . James . 2020-08-03 . What is Tripotassium Phosphate E340(iii) in Food and Functions in Cereals? . 2022-12-22 . foodadditives.net . en-US.

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