High Light-Fastness Acid Dyes Synthesized from Corresponding Anthraquinone Chromophore Utilizing a Sulfonation Reaction. I. Dye Synthesis and Characterization

As the diameter of polyamide fibers decreased to finer denier, the dyeing fastness tends to be deteriorated due to the increase of their surface area, particularly both light fastness and wash fastness. In this study, three acid dyes were synthesized utilizing a sulfonation reaction starting from corresponding hydrophobic dye (for yellow and red dye) and dye intermediate containing a sulfonic acid group (for blue dye), those featured by high light fastness property. A Gaussian structural prediction model was used to determine the structure of the acid dyes prior to dye synthesis, and the optimal structures of three acid dyes were analyzed. Dye structures prepared were confirmed by ¹H-NMR, mass spectroscopy, and elemental analysis. By using a UV-vis spectrophotometer, the absorption maxima and molar extinction coefficient were also measured for three acid dyes comparing to that of the corresponding disperse dye or blue dye intermediate. Judging from spectroscopic data, the introduction of sulfonyl groups led to increase of molar extinction coefficient and a bathochromic shift.