Synthesis and evaluation of a series of novel monoazo disperse dyes derived from N-carboxylic acid-1,8-naphthalimide on poly(ethylene terphthalate)

A series of novel monoazo disperse dyes based on N-carboxylic acid-1,8-naphthalimides have been synthesized via 4-(4-amino-1,8-naphthalimido) butanoic acid as diazo components and various couplers. The synthesized dyes were characterized with elemental analysis, differential scanning colorimetry, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and UV-visible spectroscopic techniques. The molar extinction coefficient, wavelength maxima, and solvatochromism effect were obtained using chloroform, acetone, and N,N-dimethyl formamide as solvent. The results showed that the synthesized dyes had molar extinction coefficient of 20908 to 38939 l mol⁻¹ cm⁻¹, wavelength maxima of 409–549 nm, and positive solvatochromism by changing solvent from chloroform to N,N-dimethyl formamide. The synthesized dyes were applied on poly(ethylene terephthalate) using high temperature method. Dyes 1 and 2 showed high build-up properties on poly(ethylene terephthalate), whereas dyes 3 and 4 offered medium build-up. All the dyes offered excellent heat fastness, good wash and rubbing fastnesses on poly(ethylene terephthalate) fabrics. The hydrolysis of the synthesized dyes in alkali media indicated that the presence of a carboxylic acid group within the dye molecules provides alkali-clearable potential.