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AssigneeBayer Aktiengesellschaft
InventorsAlois Gotteschlich, Klaus Leverenz
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Azo dyestuffs having the formula ##EQU1## in which A is an aromatic carbocyclic radical containing the CN substituent in the o-position to the azo group and K is the radical of a coupling component as well as the process for their production are disclosed. The process involves cyano exchange between a metal cyanide, e.g. CuCN and the corresponding dyestuff containing Cl or Br instead of CN, in an organic solvent particularly polar aprotic organic solvents, e.g. dimethyl sulfoxide. The dyestuffs are suitable for dyeing a variety of fiber materials such as cotton, wool, silk as well as snythetic materials such as polyamide and polyethylene terphthalate to give dyeings which are characterized by great clearness and good general fastness properties.
Process for the production of azo dyestuffs containing at least one cyano group in the diazo component ortho to the azo group, which comprises reacting at a temperature from about room temperature to less than 100.degree.C an azo dyestuff of the formula X--A--N=N--K wherein A stands for an aromatic carbocyclic radical linked to the azo group by a nuclear carbon atom, X stands for Cl or Br linked by a nuclear carbon atom to A in the ortho position to the azo group, and K stands for the radical of a coupling component linked by a nuclear carbon atom to the azo group, with a metal cyanide in a polar aprotic organic solvent with the exchange of the substituent X for cyano wherein the metal cyanide is copper (I) cyanide or copper (I) cyanide formed in situ by the reaction of alkali metal cyanide with a suitable copper (II) salt.
Dependencies are inferred from the claim text.