The synthesis of azo dyes involves a chemical reaction between a diazonium salt and a coupling component. Typically, the diazonium salt is prepared from an aromatic amine through a process called diazotization, where the amine is treated with nitrous acid. This reaction produces a highly reactive diazonium compound. Next, the diazonium salt is combined with a coupling agent, often an aromatic compound with an electron-donating group. This reaction results in the formation of the azo bond (-N=N-), creating the vibrant colors characteristic of azo dyes. These dyes are widely used in textiles, food, and cosmetics.