Synthesis of Novel and Thermally Stable Water Insoluble Coumarin-based Azo Dyes via a Mild and Green Procedure

A series of novel azo coumarin dyes were synthesized by the diazotization of 7-amino coumarins in the presence of catalytic amounts of tungstate sulfuric acid (TSA) followed by coupling with phenol derivatives. Tungstate sulfuric acid catalyzes this reaction at room temperature and short reaction time with high yields.