Verfahren zur Herstellung wasserunlöslicher Disazofarbstoffe

The invention comprises water-insoluble disazo dyestuff of the formula wherein A represents a benzene residue which may be substituted, and R represents a 2-hydroxynaphthalene residue or a 2-aminonaphthalene residue bound to the azo group in the 1-position. They may be obtained by coupling a diazo compound of an aminoazo dyestuff free from groups imparting solubility in water, which dyestuff corresponds to the formula with a 2-hydroxy- or 2-amino-naphthalene capable of coupling in the 1-position under alkaline or acidic conditions respectively. The benzene residue A may be substituted by halogen atoms, alkyl or alkoxy groups. The coupling components may be 2-hydroxynaphthalenes of the formula wherein Y represents hydrogen, carbalkoxy or -CONH-aryl and Z represents hydrogen, halogen, alkyl or alkoxy. The diazomonoazo compounds are coupled with the end components in an alkaline medium. An agent which assists couplign may be added, for example, pyridine or picoline. The dyestuffs of the above formula are suitable for dyeing and printing polyester fibrous material, especially polyethylene terephthalate to give strong orange to violet tints. Examples are given for the production of the dyestuffs.