Para Toluene Sulfonic Acid, p-Toluenesulfonic Acid, Tosylic acid, Tosic acid, TsOH, PTSA, 104-15-4, 6192-52-5

Para Toluene Sulfonic Acid, p-Toluenesulfonic Acid, Tosylic acid, Tosic acid, TsOH, PTSA, 104-15-4, 6192-52-5

p-Toluenesulfonic acid (PTSA, CAS 104-15-4 for the anhydrous form and 6192-52-5 for the monohydrate) is a strong organic acid widely used as a catalyst in organic synthesis, polymer chemistry, and industrial processes. It is valued for its high acidity, stability, and solubility in polar solvents.

Technical Overview

Chemical Identity

• IUPAC Name: 4-Methylbenzenesulfonic acid

• Other Names: Tosylic acid, Tosic acid, TsOH, PTSA

• CAS Numbers:

  • 104-15-4 → Anhydrous form

  • 6192-52-5 → Monohydrate form

• Molecular Formula: C7H8O3S

• Molar Mass:

  • 172.20 g/mol (anhydrous)

  • 190.22 g/mol (monohydrate)

Physical Properties

• Appearance: White to colorless crystalline solid

• Melting Point: ~106–107 °C

• Boiling Point: ~116 °C (decomposes)

• Density: ~1.07 g/cm³

• pKa: ~ -0.4 (strong acid, comparable to H2SO4)

• Solubility: Highly soluble in water, methanol, ethanol, acetone, DMSO

Industrial and Laboratory Applications

1. Catalysis

• Esterification & Acetalization: PTSA is a common acid catalyst for producing esters and acetals.

• Polymerization: Used in the synthesis of phenolic resins, epoxy resins, and other polymers.

• Organic Transformations: Facilitates dehydration, rearrangements, and sulfonation reactions.

2. Chemical Intermediate

• Pharmaceuticals: Intermediate in drug synthesis.

• Dyes & Pigments: Used in the production of azo dyes and other colorants.

• Surfactants: Functions as a sulfonating agent in detergent chemistry.

3. Specialty Uses

• Analytical Chemistry: Employed in titrations and as a strong acid reference.

• Cosmetics: Occasionally used as a surfactant or pH adjuster in formulations.

Safety and Handling

• Hazards: Corrosive; causes severe irritation to skin, eyes, and respiratory tract.

• Precautions: Use gloves, goggles, and work under ventilation.

• Storage: Keep in a dry, inert atmosphere at room temperature; hygroscopic and absorbs moisture readily.

Quick Comparison Table

In summary: PTSA is a versatile strong organic acid with broad applications in catalysis, polymer chemistry, pharmaceuticals, and industrial processes. Its dual CAS numbers distinguish between the anhydrous and monohydrate forms, both widely used depending on storage and application needs.

p-Toluenesulfonic Acid (PTSA), including the distinction between its two CAS numbers and how each form is used across industries:

Chemical Identity

• Name: p-Toluenesulfonic Acid (PTSA)

• Other Names: Tosylic acid, Tosic acid, TsOH

• CAS Numbers:

  • 104-15-4 → Anhydrous form

  • 6192-52-5 → Monohydrate form

• Formula: C7H8O3S

• Molecular Weight:

  • 172.20 g/mol (anhydrous)

  • 190.22 g/mol (monohydrate)

Industrial Suitability and Usage

Key Notes

• Anhydrous PTSA (104-15-4): Preferred in industrial-scale processes due to its stronger activity and widespread use in pharmaceuticals, agrochemicals, polymers, and dyes.

• Monohydrate PTSA (6192-52-5): Favored in laboratory and specialty applications because it is more stable, easier to handle, and suitable for analytical chemistry and niche formulations.

In short: anhydrous PTSA (104-15-4) dominates in heavy industry, while monohydrate PTSA (6192-52-5) is chosen for laboratory, cosmetic, and controlled applications.