تحضير صباغ ثنائي الآزو انطلاقاً من مركب حلقي غير متجانس

Abstract

In this research, a bifunctional azo dye was synthesized through a two-step process.

Step 1:

The synthesis started from 2-(5-amino-4,3,1-thiadiazol-2-yl) phenol, which was prepared by reacting salicylaldehyde with thiosemicarbazide to form the corresponding Schiff base, 2-(2-hydroxybenzylidene) hydrazinecarbothioamide (salicylaldehyde thiosemicarbazone). Cyclization of this intermediate was carried out in the presence of ferric chloride to obtain 2-(5-amino-4,3,1-thiadiazol-2-yl) phenol. The compound was then diazotized at a temperature between 0–2 °C and coupled with β-naphthol in a 1:1 molar ratio. This reaction produced 1-((5-(2-hydroxyphenyl)-1,3,4-thiadiazol-2-yl) diazenyl) naphthalen-2-ol (a monoazo dye) as a green-colored product with a yield of 88%.

Step 2:

In the second step, the monoazo dye obtained from the first stage was reacted with diazotized sulfanilic acid in a 1:1 molar ratio under continuous stirring at room temperature for three hours. This reaction produced a red precipitate corresponding to a diazo dye, with a yield of 80%.

The progress of the reactions was monitored using thin-layer chromatography (TLC). The final product was purified and separated chromatographically. The expected structure of the synthesized dye was confirmed using spectroscopic techniques, including ¹H NMR, ¹³C