p-Toluenesulfonic acid monohydrate is a white acicular crystal or crystalline powder with strong acidity and hygroscopicity. It has no obvious odor but is strongly irritating and corrosive to the skin, eyes and respiratory tract. As a strong organic acid, it is a common non-oxidizing acid catalyst and chemical intermediate, widely used in organic synthesis, pharmaceuticals, pesticides, dyes and other fields.

1. Organic synthesis catalyst: Used in esterification, acetalization, dehydration, etherification, polymerization and other reactions. As an alternative to sulfuric acid catalysis, it produces fewer side reactions and yields products with high purity.
2. Pharmaceutical / pesticide intermediate: Key raw material for the synthesis of antibiotics, antifungals, herbicides and insecticides.
3. Dye / pigment industry: Intermediate for the production of acid dyes, reactive dyes and organic pigments.
4. Electroplating & metal treatment: Brightener and conductive salt for nickel plating / zinc plating; additive for pickling and passivation solutions of aluminum-magnesium alloys.
5. Others: Detergent auxiliary, resin curing agent, film hardener, electrolyte additive for lithium-ion batteries.