2-hydroxy-4-n-butoxy-5-bromoacetophenone thiosemicarbazone as an extractive spectrophotometric reagent for nickel

2-hydroxy-4-n-butoxy-5-bromoacetophenone thiosemicarbazone (HBBrAT) is spectrophotometric reagent for nickel (II) in chloroform. The metal ion reacts with 2-hydroxy-4-n-butoxy-5- bromoacetophenone thiosemicarbazone (HBBrAT) forming a dark brown coloured complex in the pH range 7.0-11.0. The complex shows maximum absorption at 440 nm. Beer's law is obeyed in the range 2.74-6.86 µg/mL. The molar absorptivity and Sandell's sensitivity are found to be 5229 L [mol.sup.-1] [cm.sup.-1] and 0.0105 µg [cm.sup.-2], respectively. The solid complex have been isolated and characterized on the basis of elemental analysis, UV, IR, NMR and Mass spectra. HBBrAT is found to be a selective and strong chelating agent for nickel. The results deduced from Job's method of continuous variation, the mole ratio and the slope ratio method showed that metal: ligand ratio in the complex to be 1:2. The stability constant of the complex found to be 1.92 x [10.sup.7]. The free energy change for the complex formation reaction is found to be -10.158 K cal/mole at 32°C. The complex is fairly stable for about 24 h and up to 55°C. Keywords: bromoacetophenone; thiosemicarbazone; spectrophotometric determination; spectral study