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Pyridinium p-toluenesulfonate

Pyridinium p-toluenesulfonate (PPTS) is a salt of pyridine and p-toluenesulfonic acid. It is a colourless solid.

Pyridinium p-toluenesulfonate
Pyridinium p-toluenesulfonate.svg
IUPAC name
4-methylbenzenesulfonate; pyridin-1-ium
Other names
pyridinium p-toluenesulfonate
3D model (JSmol)
Abbreviations PPTS
ECHA InfoCard 100.041.806
Molar mass 251.30 g·mol−1
Appearance Colourless solid
Melting point 120 °C (248 °F; 393 K) source[2]
Acidity (pKa) 5.21[1]
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


In organic synthesis, PPTS is used as a weakly acidic catalyst, providing an organic soluble source of pyridinium (C5H5NH+) ions. For example, PPTS is used to deprotect silyl ethers or tetrahydropyranyl ethers when a substrate is unstable to stronger acid catalysts. It is also a commonly used catalyst for the preparation of acetals and ketals from aldehydes and ketones.


  1. ^ David A. Evans (2005-11-04). "Evans pKa Table" (PDF). Retrieved 2016-03-02.
  2. ^ TOKYO CHEMICAL INDUSTRY CO., LTD. "Pyridinium p-Toluenesulfonate". Retrieved 2011-09-16.