Synthesis and application of N-butyl substituted phthalimide disperse dyes

Abstract

Three azo dyes were synthesized using N-butyl substituted phthalimides as diazo components. All of the synthesized intermediate derivatives and dyes were characterized by mass spectrometry, proton nuclear magnetic resonance, infrared (IR) and elemental analyses. Synthesized dyes were also evaluated for their dyeing behavior and fastness properties toward polyester fabric. The ultraviolet-visible absorption maxima of the dyes were observed in the range of 445–563 nm. Bromo and cyano substitutions at the 3- and/or 5- positions of the phthalimide ring resulted in hypsochromic and bathochromic shifts, respectively. IR spectra peaks at 1770 and 1395 cm−1 of hydrolyzed dye showed that C–O groups appeared under relatively mild alkaline conditions. The K/ S values of dyed polyester/elastane fabrics decreased obviously as the pH value increased. Hydrolysis of the phthalimide ring was found to be largely influenced by steric effects rather than inductive effects. Bromo substituted dyes have the lowest rates of hydrolysis. Compared with S-type dyeing disperse dyes, phthalimide dyes have lower dyeing rates and lower levelness of dye migration. The ωB97XD/6-311G(d,p) calculation found that pi-stacking interactions of phthalimide–benzene and phthalimide–phthalimide dimers increased the dye–fiber and dye–dye interactions.