ptoluenesulfonihappo

Ptoluenesulfonihappo, known in English as p-toluenesulfonic acid (PTSA), is an organosulfur compound that acts as a strong, non-volatile Brønsted acid. It is the para isomer of benzenesulfonic acid, with the chemical formula C7H8O3S. The molecule consists of a benzene ring bearing a para-methyl group and a sulfonic acid group (SO3H). PTSA is a solid at room temperature and is highly soluble in water and many organic solvents.

PTSA is commonly used as a catalyst in a wide range of organic reactions due to its strong acidity and low volatility, which facilitates reaction handling and workup compared with mineral acids. Its conjugate base, the p-toluenesulfonate anion, is a stable leaving group in certain transformations. PTSA can be prepared by sulfonation of toluene, typically giving a mixture of ortho and para isomers that are separated to obtain the para isomer.

In practice, PTSA serves as a versatile acid catalyst in esterifications, acetalizations, hydrolysis, and other acid-catalyzed processes conducted in organic media. It is valued for being soluble in organic solvents and easier to remove from reaction mixtures than volatile mineral acids. PTSA is also used in combination with other reagents to generate tosyl derivatives in various synthetic sequences, leveraging the related tosylate chemistry.

Safety considerations: PTSA is corrosive and an irritant to skin, eyes, and lungs. It should be handled with appropriate protective equipment in a well-ventilated area and stored in a dry, cool place away from incompatibles.