Synthesis of Malononitrile-Condensed Disperse Dyes and Application on Polyester and Nylon Fabrics

An active methylene compound, malononitrile, was introduced into the structures of a series of disperse dyes previously prepared by coupling phloroglucinol, barbituric acid, and α and β-naphtho to 4-amino-3-nitrobenzaldehyde. The dyes were purified by recrystallization from ethanol. The purity of the dyes was examined by thin-layer chromatography (TLC) and the dyes were characterized by visible absorption and Fourier transform infrared spectroscopy (FTIR). The malononitrile-condensed dyes produced deeper colours and shades with better fastness to wash, light, and perspiration on application to polyester and nylon fabrics when compared to their uncondensed analogue.