The synthesis and solvatochromic properties of some novel heterocyclic disazo dyes derived from barbituric acid

5-Amino-4-arylazo-3-methyl-1H-pyrazoles were diazotised and coupled with barbituric acid to provide 13 novel heterocyclic disazo barbituric acid dyes that were characterized by elemental analysis and spectral methods. The effects of varying the pH and solvent on the absorption of the dyes substituted with electron-withdrawing and electron-donating groups at their o-, m-, p-position were examined in detail.