Effect of the sulphonic group position on the properties of urea dyes

Azo dyes, analogues of C.I.Direct Red 23, have been prepared, using anilinesulphonic acids as diazo components and bis-ureido-6-(naphthol-1) as a coupling component, and their colour properties have been examined, comparing them with those of a reference dye by the differential spectra method in aqueous solutions as well as by the reflectance spectra analysis on dyed wool and cotton fabrics. It has been found that the dyes under investigation may be an alternative to the presently used conventional urea dyes.