Synthesis and Dyeing Performance of Azo Acid Dyes Derived From P-Nitroaniline on Semi- Chrome and Vegetable Tanned Leather

Abstract

P-nitro aniline dye was synthesized by coupling reaction of diazonium salt with 2-amino-8-naphthol Sulphuric acid (J-acid) and 8-animo-1-naphthol 3-6 disulphuric acid (H-acid). Scheme (1) showed the reaction of p-nitro aniline with sodium nitrite in the presence of hydrochloric acid for the production of dye intermediate. Scheme (2) showed the reaction between the dye intermediate and J.acid to generate dye A. Scheme (3) showed the reaction between the dye intermediate and H.acid to yield dye B. The synthesized dyes gave a maximum absorption within the UV- a visible region with λ_max465-500 nm which indicate bathochromic shift and the infra-red spectra showed peaks at 1582-1421cm-¹ (due to azo group (N=N) stretching vibration), at 3400 – 3200 cm^-1 (due to  (OH&NH) medium & broad stretching vibration ), at 2830-26-95cm^-1  (due to aromatic group ( C-H) stretching vibration ), at 1760-1640 cm^-1 (due to carbonyl group (C=O) stretching vibration ), at 1342-1266 cm^-1  (due to aromatic amine group (C-N) stretching vibration ) and at 2260-2222 cm^-1 ( due to nitrile ( C=N ) stretching vibration ) Fastness properties to light and wash fastness rating of both substrate were (4-5) generally indicating very good to excellent which is attributed to proper penetration, levelness and solubility were achieved. The good shades observed such as light brown and plumb purple may be due to better substantivity, affinity as well as good solubility of the dyes on semi-chrome and vegetable-tanned leather.