Synthesis and Characterization of New Azo Dye Derived from Sulfamethaxolevia Diazonium Reaction and Study its Abilityas an Acid-base Indicator

Background: Most azo dyes are synthesized by diazotization of a primary amine, followed by conjugation with one or more electron-rich nucleophiles. Objective: This study presents the synthesis of a new azocompound by converting sulfamethoxazole to a diazonium salt. Methods: via reaction with hydrochloric acid and sodium nitrite at temperatures between 0 and 5 °C, the resulting salt is then coupled with a 4-methoxyphenol reagent in alkaline medium at the above temperatures to produce an azodye given the IUPAC name of (4-((2-hydroxy-5-methoxyphenyl)diazenyl)-N-(5-methylisoxazol-3yl)benzenesulfonamide). The azo dye precipitate was purified by crystallization methods using a solvent mixture of ethanol water. Characterization was done using different analytical methods such as IR, UV-Vis and H1-NMR in addition to measurements of physical properties. Results: The reddish-pink azo compound gave a maximum absorbance of 495 nm. Acid-base titrimetric analysis was conducted to examine the chemical indicator properties of the azo dye. Clear color differences were obtained between two spaces in the pH range 2-12, where a reddishpink color was obtained in the basic medium and a yellow color in the acidic medium. Conclusions: A new azo dye successfully presented its properties as an indicator.