Synthesis of red azo dyes from cardanol and aromatic diamine

Abstract

A series of monoazo and disazo dyes was synthesized by a coupling reaction of cardanol with a diazonium salt of various aromatic amines. Effect of the central aromatic moieties on the dye formation, solubility and photophysical benhavior of the azo compounds was investigated. In all cases, the introduction of cardanol in the dye molecules was proved to be advantageus in giving dyes with satisfactory solubility, The resulting azo dyes appeared in yellow or red color. The selected red disazo dye 18 exhibited high solubility in gasoline 91 and common organic solvents. The ASTM test methods revealed that the physical properties of gasoline 91 were unaffected by the presence of the pure azo dye 18 at a concentration of 6 ppm or the crude of azo dye 18 at a concentration of 18 ppm. The red disazo dye 18 was found to be stable in gasoline 91 for at least 3 months. Therefore, it can be readily applied as dye for commercial gasoline 91 in both pure and crude forms.