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(p-Toluenesulfonic Acid)

Other Names:

4-Methylbenzenesulfonic acid

Tosic acid



General Information:


CAS Number: 104-15-4 (anhydrous)

    6192-52-5 (monohydrate)

Molecular Weight: 172.20 g/mol (anhydrous)

    190.22 g/mol (monohydrate)

Appearance: Colorless/white solid

Melting Point: 103-106 C (monohydrate)

p-TsOH is one of the most commonly used organic acid catalysts. p-TsOH is a strong organic acid. Unlike most strong acids, p-TsOH exists as a convenient to handle solid.

Common Uses:

- Acid catalyst for THP protection

- Acid catalyst for THP deprotection


p-Toluenesulfonic acid is a corrosive strong acid. It is extremely destructive to skin, eyes, tissues of the mucous membranes and upper respiratory tract.


1) Wikipedia: p-Toluenesulfonic acid (link)

2) p-Toluenesulfonic acid monohydrate (link)

3) Reich, H. J.; Rigby, J. H.; Handbook of Reagents for Organic Synthesis, Acidic and Basic Reagents