The present invention refers to dyestuffs of the general formula (I) wherein R, X, Y and Z are defined as given in claim1, dyestuff mixtures and hair dye compositions comprising them, as well as a process for colouring hair.本發明係關於通式(I)之染料其中R、X、Y及Z為如申請專利範圍第1項中所定義者,染料混合物及含彼之染髮組成物,及染髮之方法。