Synthesis, structural characterization and thermal studies of a novel reagent 1-[(5-benzyl-1,3-thiazol-2-yl)diazenyl]naphthalene-2-ol

A new thiazolylazo reagent 1-[(5-benzyl-1,3-thiazol-2-yl)diazenyl]naphthalene-2-ol has been synthesized via arylation of acrolein and further diazotization and diazocoupling with 2-naphthol. The chemical structure of the compound was confirmed by IR, NMR: H-1, C-13, COSY, HSQC and SALDI-MS spectral data. The DSC method was employed to determine the melting point and the enthalpy of fusion (T (fus) = 159.7 A degrees C and Delta H (fus) = 28.0 kJ mol(-1), respectively). Thermal stability and decomposition studies of the obtained azo dye were performed in air and nitrogen atmosphere using the TG technique. The evolved gases from the heated sample were registered on FTIR spectra. The decomposition of the azo dye in air atmosphere occurred in five consecutive stages. The pK (a) ionization constants of the substance were determined in ethanol-water mixture (1:1 v/v) by means of the spectroscopic method and were found to be equal to 0.41 for pK (a1) and 9.59 for pK (a2). Using the spectrophotometric procedures, the methods for determination of trace amounts of toxic metallic ions with the new reagent were characterized and limits of detection were calculated.