Pyridinium p-toluenesulfonate

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

Pyridinium p-toluenesulfonate

Names
IUPAC name 4-methylbenzenesulfonate; pyridin-1-ium
Other names pyridinium p-toluenesulfonate, pyridinium tosylate
Identifiers
CAS Number	24057-28-1 Y
3D model (JSmol)	Interactive image
Abbreviations	PPTS
ChemSpider	141806 Y
ECHA InfoCard	100.041.806
PubChem CID	466102
CompTox Dashboard (EPA)	DTXSID5066952
InChI InChI=1S/C7H8O3S.C5H5N/c1-6-2-4-7(5-3-6)11(8,9)10;1-2-4-6-5-3-1/h2-5H,1H3,(H,8,9,10);1-5H Y Key: ZDYVRSLAEXCVBX-UHFFFAOYSA-N Y InChI=1/C7H8O3S.C5H5N/c1-6-2-4-7(5-3-6)11(8,9)10;1-2-4-6-5-3-1/h2-5H,1H3,(H,8,9,10);1-5H Key: ZDYVRSLAEXCVBX-UHFFFAOYAE
SMILES CC1=CC=C(S(=O)([O-])=O)C=C1.C2=[NH+]C=CC=C2
Properties
Chemical formula	C12H13NO3S
Molar mass	251.30 g·mol−1
Appearance	Colourless solid
Melting point	120 °C (248 °F; 393 K) source[1]
Acidity (pKa)	5.21[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Uses

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.