Pyridinium p-toluenesulfonate
# Pyridinium p-toluenesulfonate

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

## Uses

In organic synthesis, PPTS is used as a weakly acidic catalyst, providing an organic soluble source of pyridinium $(C_5H_5NH^+)$ 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.

