Synthesis of Some Monoazo Acid Dyes Based on Naphthalimides

Abstract

A series of novel monoazo acid dyes derived from naphthalimide were prepared. 4-Amino-N-methyl (alternatively N-butyl) derivatives of naphthalimide, aniline and p-nitroaniline were used as the diazo components and schaeffer's acid and H-acid constituted the coupling components. 4-Aminonaphthalimide derivatives mentioned above were prepared by standard reactions from acenaphthene as the starting material. The reaction conditions were varied in order to obtain optimal yields for each stage of the preparation to obtain the corresponding 4-aminonaphthalimide derivative as the diazo component which was subsequently purified. Diazotization and coupling reactions were carried out in order to obtain the final acid dyes. Again maximal yields were sought after and the reaction conditions were varied accordingly. All intermediates and dyes were recrystallized in order to be attained in a purified form. The obtained dyes and their corresponding intermediates were characterized by the use of elemental analysis, DSC, FTIR, ¹H NMR and UVvisible spectroscopic techniques. Spectrophotometric investigations of the prepared dyes in different solvents were carried out in order to obtain their absorption maxima, solvatochromic effects and various intensities. The acid dyes were finally dyed on polyamide fibres in order to investigate their dyeing properties and the obtainable colour gamut.