Spectrophotometric determination of copper after adsorption of its 1-phenyl-4,4,6-trimethyl(1H, 4H)-pyrimidine-2-thiol complex onto microcrystalline naphthalene

A selective Spectrophotometric method has been developed for the trace determination of copper after adsorption of its 1-phenyl-4,4,6-trimethyl(1H, 4H)-pyrimidine-2-thiol (PTPT) complex onto microcrystalline naphthalene. The complex is quantitatively adsorbed on naphthalene in the pH range 7.5–11.5, separated by filtration, dissolved in dimethylformamide (DMF) and determined spectrophotometrically at 400 nm. Beer's law is obeyed in the concentration range 2.5–37.5 g of copper in 10 ml of DMF. The molar absorptivity and Sandell's sensitivity are 1.30 × 10⁴1 · mol^–1 · cm^–1 and 0.0048g cm^–2, respectively. Ten replicate analyses of a solution containing 20.0 g of copper gave a mean absorbance of 0.410 with a relative standard deviation of 0.91 %. The interferences of various ions have been studied and the method has been validated by the determination of copper in various standard reference materials, beers, wines, human hair, goat liver and environmental samples.On leave from St. Stephen's College, Delhi 110 007, India     

Trifluoroethylxanthate as an Analytical Reagent: AAS of Zinc,Antimony and Lead After Coprecipitation of Their Trifluoroethylxanthates onto Microcyrstalline Naphthalene

Abstract

A sensitive method has been developed for the direct atomic absorption spectrometric determination of zinc, antimony and lead after coprecipitation of their trifluoroethylxanthates onto microcrystalline naphthalene. The metal xanthates are quantitatively coprecipitated over the pH ranges: Zn, 5.9–8.4; Sb, 4.0–6.0 and Pb, 4.0–11.0. The solid mass consisting of the metal complex and naphthalene is dissolved in DMF. This solution is aspirated into an air-acetylene flame at 213.9, 217.6 and 217.0nm for Zn, Sb and Pb, respectively. Beer's law is obeyed in the concentration range 2–50, 3–90 and 5–60 μg of Zn, Sb and Pb, respectively in 10ml of the final DMF solution. RSDs are at the ± (0.5–0.6)% level (n=10). The concentration for 1% absorption is 0.019, 0.035 and 0.060μg/ml for Zn, Sb and Pb, respectively. The method is suitable for the preconcentration of the metals from a larger volume of the aqueous phase, and has been employed for their determination in standard reference materials. It may be employed for the simultaneous determination of Zn, Pb and Sb in a solution by pH control.     

Metal complexation with 2-hydroxy-6-methylpyridine-3-carboxylic acid

Metal complexation with 2-hydroxy-6-methylpyridine-3-carboxylic acid has been studied. The ligand finds use in detection and determination of iron (III). The order of stability constants of the bivalent transition metal complexes is Cu > Zn > Fe > Ni > Co > Mn. b]¦de¦Die Komplexbildung von Metallen mit 2-Hydroxy-6-methylpyridin-3-carbonsäure wurde untersucht. Der Ligand findet Verwendung beim Nachweis und bei der Bestimmung von Eisen(III). Die Reihenfolge der Stabilitätskonstanten der Komplexe mit zweiwertigen Überg angsmetallen ist Cu > Zn > Fe > Ni > Co > Mn.     

Synthesis and electrochemical studies of charge-transfer complexes of thiazolidine-2,4-dione with σ and π acceptors

In the present work, we report the synthesis and characterization of novel charge-transfer complexes of thiazolidine-2,4-dione (TZD) with sigma acceptor (iodine) and pi acceptors (chloranil, dichlorodicyanoquinone, picric acid and duraquinone). We also evaluated their thermal and electrochemical properties and we conclude that these complexes are frequency dependent. Charge-transfer complex between thiazolidine-2,4-dione and iodine give best conductivity. In conclusion, complex with sigma acceptors are more conducting than with pi acceptors.     

Reduction of chromano–piperidine-fused isoxazolidines: Tandem intramolecular rearrangements leading to 2-(methylamino)-4-oxo-N-phenyl-N-propyl-4H-chromene-3-carboxamide

Reductive ring opening of isoxazolidine moiety of chromano–piperidine-fused isoxazolidines (3a–c) with HCOONH₄ and 10% Pd/C in a mixture of solvents (THF/MeOH) at ambient temperature, affords novel 2-(methylamino)-4-oxo-N-phenyl-N-propyl-4H-chromene-3-carboxamide (4), which is apparently derived from reductive NO bond cleavage followed by tandem intramolecular rearrangements. Plausible mechanistic rationale for the formation of compound 4 is proffered.