To obtain a high-purity azo dye having a sulfo group easily in a simple manner by condensing a specific azo dye with a specific amine deriv.
An azo dye of formula I is condensed with an amine deriv. of formula II to give an azo dye of formula III having a sulfo group. In those formulas, 'Dye' is an azo dye; R is H, alkyl, or aryl; L is a divalent linking group provided L may combine with R to form a ring; and M1 and M2 are each H, an alkali metal, or ammonium. 'Dye' in the formulas is represented by formula IV, wherein either Cp or A has a carboxyl group. Generally, an azo dye is prepd. by the coupling reaction of a coupler component CpH with a diazonium salt derived from an amine deriv. ANH2, wherein A is an aryl or heterocyclic group. L in formula II is pref. a m- or p-phenylene group. A high-purity azo dye having a sulfo group is obtd. at a high productivity by condensing an azo dye of formula I with an amine deriv. of formula II.
ONO MICHIO
KATO YASUHIRO
