Patent ID: 7521545

Claim:
A process for producing an aromatic azo compound represented by the formula (III): wherein the A ring is a benzene ring that has at least one electron-withdrawing group in addition to the diazonium group and may be further substituted; R 1 and R 2 are the same or different and are each independently C 1-6 alkyl; R 3 is optionally substituted aryl; and R 4 , R 5 and R 6 are the same or different and are each independently hydrogen atom, C 1-6 alkyl, halogen, C 1-6 alkoxy or C 1-6 alkylthio, or a salt thereof, which comprises subjecting a benzenediazonium salt represented by the formula (I): wherein the A ring is as defined above, and a compound represented by the formula (II): wherein R 1 to R 6 are as defined above; and X − is an anion, or a salt thereof, to diazo coupling in a mixed solvent substantially consisting of water and an organic solvent (other than carboxylic acid solvents).