A novel approach has been established for accessing structurally diverse azo disperse dyes with improved fastness properties by employing an Ugi four-component reaction (Ugi-4CR). The process includes three steps: (1) Ugi-4CR of aniline, cyclohexyl isocyanide, formic acid , and an aromatic aldehyde; (2) selective hydrolysis of amide functionality in the Ugi product; and (3) coupling the hydrolysis product with an aryl diazonium salt. Employing Ugi-4CR herein had advantages over easily controlling the molecular weight/size of the dye. Six new azo disperse dyes were synthesized and their structures were fully characterized by 1 H NMR, 13 C NMR, MS, and FT-IR. It was found that the washing and sublimation fastness properties of the obtained azo disperse dyes on both poly (ethylene terephthalate) (PET) and nylon fibers were remarkably improved as compared with conventional C.I. Disperse Orange 3. The improved fastness properties should be attributed to the moderately increased molecular weight/size and the amide functionality introduced in Ugi-4CR.
Gaofeng Feng,Hong-Fei Qian,Gang Bai,Yan-Chun Liu,Ling-Ling Hu
A series of new kinds of diester/diurethane tethered azo disperse dyes were synthesized through the reaction between the hydroxyl group in disperse dyes, such as C. I. Disperse Red 1 ( 1a ), C. I. Disperse Red 13 ( 1b ), and C. I. Disperse Blue 106 ( 1c ), and terephthaloyl chloride or p -phenylene diisocyanate . Structures of these new dyes were fully characterized with NMR, MS, and FT-IR. Visible absorption measurement in DMF indicated that all new diester/diurethane tethered dyes exhibited a little shorter maximum absorption wavelength and much higher molar extinction coefficient than their prototypes. Moreover, the fastnesses to wash and sublimation of dyeing on polyurethane fibre were dramatically improved due to the dye's moderately increased molecular size. It is an attractive new strategy to synthesize a library of tethered dyes with improved fastness properties using various different tethering agents or disperse dyes.