TY - JOUR
T1 - Synthesis and chromogenic properties of water-soluble substituted 2-pyridyl-3'-sulphophenylmethanone 2-pyridylhydrazones and spectrophotometric and analogue derivative spectrophotometric determination of trace amounts of cobalt with 2-pyridyl-3'-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone
AU - Odashima, Tsugikatsu
AU - Kikuchi, Takemitsu
AU - Ohtani, Wataru
AU - Ishii, Hajime
PY - 1986/1/1
Y1 - 1986/1/1
N2 - Three water-soluble hydrazones, in which the 5-position of the pyridine ring in the hydrazine moiety of 2-pyridyl-3'-sulphophenylmethanone 2-pyridylhydrazone (PSPH) was substituted a methyl, chloro or nitro group, have been synthesised and their chromogenic properties and reactivities with metal ions investigated. The acid dissociation constants (Ka) of the synthesised hydrazones were determined spectrophotometrically. These values obeyed Hammett's law, the inductive effect of the substituents being found to reflect the pKa values. Of the synthesised hydrazones, 2-pyridyl-3'-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone (PSNPH) is the most sensitive for cobalt(II) determination. It reacts with cobalt(II) to form a 1:2 (metal to ligand) complex. This complex is rapidly oxidised above pH 2 to give a stable cobalt(III) complex with an absorption maximum at 496 nm. Beer's law is obeyed over the range 0.05-1.0 μg ml-1 of cobalt and the apparent molar absorptivity of the complex is 5.69 × 104 l mol -1 cm-1 at 496 nm. A sensitive and practical spectrophotometric method for the determination of trace amounts of cobalt with PSNPH is proposed and has been successfully applied to the determination of cobalt in steel samples. The method may be made more sensitive by employing an analogue derivative spectrophotometric technique.
AB - Three water-soluble hydrazones, in which the 5-position of the pyridine ring in the hydrazine moiety of 2-pyridyl-3'-sulphophenylmethanone 2-pyridylhydrazone (PSPH) was substituted a methyl, chloro or nitro group, have been synthesised and their chromogenic properties and reactivities with metal ions investigated. The acid dissociation constants (Ka) of the synthesised hydrazones were determined spectrophotometrically. These values obeyed Hammett's law, the inductive effect of the substituents being found to reflect the pKa values. Of the synthesised hydrazones, 2-pyridyl-3'-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone (PSNPH) is the most sensitive for cobalt(II) determination. It reacts with cobalt(II) to form a 1:2 (metal to ligand) complex. This complex is rapidly oxidised above pH 2 to give a stable cobalt(III) complex with an absorption maximum at 496 nm. Beer's law is obeyed over the range 0.05-1.0 μg ml-1 of cobalt and the apparent molar absorptivity of the complex is 5.69 × 104 l mol -1 cm-1 at 496 nm. A sensitive and practical spectrophotometric method for the determination of trace amounts of cobalt with PSNPH is proposed and has been successfully applied to the determination of cobalt in steel samples. The method may be made more sensitive by employing an analogue derivative spectrophotometric technique.
KW - 2-pyridyl-3'-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone
KW - Analogue derivative spectrophotometry
KW - Cobalt determination
KW - Spectrophotometry
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U2 - 10.1039/AN9861101383
DO - 10.1039/AN9861101383
M3 - Article
AN - SCOPUS:0010335532
VL - 111
SP - 1383
EP - 1387
JO - Analyst
JF - Analyst
SN - 0003-2654
IS - 12
ER -