Pyridinium p-toluenesulfonate is a salt of pyridine

Pyridine

Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...

 and p-toluenesulfonic acid

P-Toluenesulfonic acid

p-Toluenesulfonic acid or tosylic acid is an organic compound with the formula CH3C6H4SO3H. It is a white solid that is soluble in water, alcohols, and other polar organic solvents. The 4-CH3C6H4SO2- group is known as the Tosyl group and is often abbreviated as Ts or Tos...

. It is often called PPTS. It appears a colourless solid.

Masaki Miyashita studied this compound and found it efficient to deprotect tetrahydropyranyl group

Tetrahydropyran

Tetrahydropyran is the organic compound consisting of a saturated six-membered ring containing five carbon atoms and one oxygen atom. The compound is a colourless volatile liquid, but is obscure. Derivatives of tetrahydropyran are, however, more common. Tetrahydropyranyl ethers derived from the...

 (THP).

Uses

In organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

, p-toluenesulfonate is used as a catalyst due to its weak acidity. For example, PPTS is available to deprotect silyl group or tetrahydropyranyl group

Tetrahydropyran

Tetrahydropyran is the organic compound consisting of a saturated six-membered ring containing five carbon atoms and one oxygen atom. The compound is a colourless volatile liquid, but is obscure. Derivatives of tetrahydropyran are, however, more common. Tetrahydropyranyl ethers derived from the...

when a substrate is unstable to strong acid.