PURPOSE: To obtain an azo dye with excellent qualities in a high yield by coupling a diazo compound prepared by reacting a specific amine with an excess of an alkali metal nitrite and a mineral acid.
CONSTITUTION: There is provided a process for the preparation of an azo dye starting from an amine of formula I, wherein the aforementioned amine is continuously reacted with an alkali metal nitrite and a mineral acid at a temperature ranging from 3 to 65°C, using a 3-15% excess of the alkali metal nitrite to give a diazo compound, which is subsequently coupled to a coupling component. In the formula, R1 is H or nitro, preferably nitro, more preferably nitro in the p-position to the NH group. R2 is H, sulfo, a 1-4C alkyl or 1-4C alkoxy, preferably H, more preferably sulfo. Preferably is employed an amine of formula II, in particular 4'-amino-4-nitrodiphenylamine-2-sulfonic acid as an aromatic amine.
KAARUUFURIIDORIHI HARUBURUGAA
HERUBERUTO MAUZAA
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