Chlorobenzonitrile is an aromatic nitrile intermediate containing a cyanide group and a chlorine atom. Due to its dual functional group reactivity, it has important applications in the fields of medicine (such as letrozole), pesticides, dyes, and polymer materials.

In the pesticide industry, chlorobenzonitrile (PCBN, 4-chlorobenzamide) is not an end-product pesticide but a "benzamide skeleton" type key intermediate - relying on the two functional groups of -Cl and -CN on the ortho position of the benzene ring, it undergoes halogenation, acylation, coupling, and heterocyclic ring closure, mainly leading to two lines of herbicides and insecticides, with a small amount extending to fungicides.