US Patent 7258702 Yellow cationic dyes for dyeing of organic material

The present invention relates to novel cationic yellow dyes of formula (1) wherein R1 and R2 are each independently of the other a C1-C8alkyl radical or an unsubstituted or substituted benzyl radical, R3 is hydrogen, C1-C8alkyl, C1-C8alkoxy, cyanide or halide, preferably hydrogen and X is an anion, with the proviso that at least one of the substitutents R1 is a benzyl radical and R2 is a methyl radical, R2 is not hydrogen, also to compositions therof, especially comprising other dyes, to processes for the preparation therof and to the use therof in the dyeing of organic material, such as keratin, wool, leather, silk, cellulose or polyamides, especially keratin-containging fibres, cotton or nylon, and preferably human hair.