Novel azo disperse dyes derived from aminothiophenes: Synthesis and UV–visible studies

A number of red to violet thienyl-2-azo and thienyl-5-azo disperse dyes were prepared using Gewald's methodology. Structural characterization of these novel dyes was carried out using IR, NMR and mass spectroscopy. UV–visible studies of these azo dyes in a number of polar solvents showed a considerable difference in the λmax. The introduction of various substituents to these azo dyes as well as the polarity of solvents resulted in absorption in the visible region ranging from 461 to 555 nm.