Synthesis of mono azo dyes using the ionic liquid 1-(3-trimethoxysilylpropyl)-3-methylimidazolium nitrite as a catalyst

Azo dyes were prepared via in situ azo-coupling reactions of these diazoniums with active aromatic compounds under solvent-free conditions in very short reaction time in excellent yields. the ionic liquid 1-(3-trimethoxysilylpropyl)-3-methylimidazolium nitrite was used as a convenient nitrosonium source in diazotization of arylamines into their corresponding diazonium salts which were converted into their related azo dyes via the in situ azo-coupling with aniline derivatives or phenolic compounds. The ionic liquid plays a dual role as a nitrosonium source and catalyst because of its ionic characteristic. The diazotization of anilines in this ionic liquid and subsequent azo-coupling generated the related azo dyes in good to excellent yields at 0-5 °C in short reaction times via a simple experimental procedure. The isolated products were confirmed with the FT-IR spectrum, 1H-NMR, 13C-NMR spectroscopy.