No abstract

The synthesis of the electronic and infrared spectra of di-2-pyridyl ketone salicyloylhydrazone (DPKSH) and di-2-pyridyl ketone benzoylhy-drazone (DPKBH) is reported. Ultraviolet absorption spectra have been applied for determining the dissociation constants: DPKSH, pK1 = 3.5 and pK2 = 6.85; DPKBH, pK1 = 2.75 and pK2 = 10.6. These pK a values are interpreted as a function of the ortho-position of the OH group. Chelating properties of both tridentate ligands have been investigated. DPKSH forms a larger number of metal chelates in acidic media than does DPKBH. Also, it is concluded that DPKSH is a more suitable compound than DPKBH to preconcentrate and to determine heavy metal ion traces as it is inferred from the data obtained by flame AAS.

The properties of 2,6-diacetylpyridine bis(2-hydroxybenzoylhydrazone) (DAPBSH) and 2,6-diacetylpyridine bis(benzoy1hydrazone) (DAPBBH) are described. The reaction between Sb(l1l) ions and DAPBBH has been studied spectrophotometrically and the resulting orangeyellow Sb -DAPBBH complex extracted into 3-methylbutan-I -01 ( E = 1.13 x lo4 I mol-1 cm-I at 405 nm) from pH 0.5 to 5.3. The Sandell sensitivity is 0,001 1 pg cm-* in 50 ml of aqueous solution. The method described is highly selective and has been applied satisfactorily to the determination of antimony in non-ferrous alloys.