o-Toluidine is an important intermediate in the production of dyes and pigments. It can be used to prepare direct red 62, red base RL, scarlet base G, jujube red base GBC, basic fuchsin, chromol AS-D, acid red 35, 158 , 265, solvent red 124, the diazo component and coupling component of azo dyes, organic Chemicalbook pigment yellow 14, 17, blue 19; pesticide raw materials, the production of pesticide fungicides "tricyclazole", insecticides loquat , Insecticide; herbicide acetochlor; raw materials for rubber vulcanization accelerators; raw materials for saccharin; raw materials for corrosion inhibitors, etc. In organic synthesis, o-toluidine is also used to synthesize heterocyclic compounds indole and its derivatives.