diazonium compound

A diazonium compound is a salt containing the cation (positive ion) diazonium formula group where R is an aryl group, made by reacting a primary aromatic amide with nitrous acid (see nitrogen). The sensitivity of diazonium compounds to light is exploited in the diazo process or ozalid process. They couple with phenols to give azo compounds. The aliphatic diazo compounds have a related structure.