VOLUME 14, NO2, JUN 1992

SIZE AND SHAPE CHARACTERISTICS OF POLY(VINYLACETATE) IN TOLUENE BY LIGHT-SCATTERING

Light scattering measurements were performed for poly(vinylacetate), PVAc, sample in toluene at room temperature. The radius of gyration <S2>1/2 and second virial coefficient (A2) for seven fractions and crude sample was determined by using the light scattering techniques such as turbidity, zimm plot method and dissymmetry. From the data it was concluded (i) that PVAc molecules have random coil conformation in toluene at 25-degrees-C (ii). The second virial coefficient depends strikingly on molecular weight for a given solvent (iii) there is also a good correlation between mean square radius of gyration and molecular weight.read more

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BASHIR AHMAD ,NOOR UL BASAR ,NOOR AHAMD ,

LEWIS ACIDITY OF TRIS(ACETYLACETONATE) IRON (III) INTERACTIONS WITH SOME PHOSPHINE DERIVATIVES IN METHYLENE-CHLORIDE SOLUTIONS

The interactions between iron(III) acetylacetonate and a number of phosphine derivatives in methylene chloride were studied at 25-degrees-C by measuring the absorbances of the solutions at 430 nm. The absorbances were used to calculated equilibrium concentrations of the species in the solutions and then to evaluate equilibrium constants of these interactions. The equilibrium constant values indicate the following trend in the basic strength of the 1:1 adducts formed between phosphine derivatives and iron(III) acetylacetonate: (C2H5)3P>(ClC6H4)3P> (C6H5)3P>(C6H5)2(CH3O)P>C6H5(CH3)2P. The formation of the above adducts is also supported by NMR study.read more

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ALI MUHAMMAD ,

ADSORPTION OF SAMARIUM ON ACTIVATED-CHARCOAL FROM AQUEOUS-SOLUTION

Adsorption of samarium on activated charcoal has been studied as a function of shaking time, pH, concentration of adsorbate and temperature. Wavelength dispersive X-ray fluorescence spectrometer was used for measuring samarium concentration. Samarium adsorption obeys the Langmuir isotherm. DELTA H(o) and DELTA S(o) were calculated from the slope and intercept of plot 1nK(D) VS 1/T. The influence of different cations and anions on samarium adsorption has been examined. The adsorption of other metal ions on activated charcoal has been studied under optimum condition to check its selectivity for samarium. Consequently samarium was removed from the aqueous solutions containing Cs, Sr, Nd, Zn, Cu, Co, Rb and Pr. More than 98% of adsorbed samarium on activated charcoal can be recovered with 50 ml of 3 M HNO3 solution.read more

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RASHID QADEER ,M AFZAL ,M SALEEM ,J HANIF ,

SPECTROSCOPIC STUDY OF NEW SCHIFF-BASES DERIVED FROM DIBENZOYLMETHANE AND BENZOYLACETONE

UV, H-1-NMR, IR and Mass spectra of new Schiff bases derived from dibenzoylmethane and benzoylacetone are described. The strong absorption bands in the UV region between 350-380 nm have been attributed to the electronic transitions which arise from hydrogen bonded conjugate chelate rings. The other bands in the region 250-200 nm were attributed to aromatic and conjugated aromatic rings. The appearance of the signals due to the methylene protons adjacent to the nitrogen atom as a doublet centered at delta = 4.5 ppm in the NMR spectra and the ion C6II5CO+ at m/z 105 in the mass spectra were taken as evidence that these compounds exist primarily in the keto-enamine form in solution.read more

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Z H AIUBE ,B A SAEED ,N A ABOOD ,

CHROMATOGRAPHIC SEPARATIONS OF COPPER(II), NICKEL(II) AND PALLADIUM(II) CHELATES OF TETRADENTATE SCHIFF-BASES DERIVED FROM 5-METHYLHEXANE-2,4-DIONE AND 1.1.1-TRIFLUORO-5-METHYLHEXANE-2,4-DIONE

The copper(II), nickel(II) and palladium(II) chelates of the ligands bis(isopropanoyl-acetone)-ethylenediimine (H2PA2en) bis(trifluoroisopropanoyl-acetone)ethylenediimine (H2F3-PA2en) and bis(trifluoroisopropanoylacetone)propylenediimine (H2F3PA2pn) were prepa- md. The results of our thermoanalytical studies indicated that the complexes were sufficiently volatile and could elute from the gas chromatographic columns. Adequate separation of palladium from copper and nickel complexes or H2PA2en were obtained on a ps chromatographic column (3m x 3mm) packed with OV101, 3% on Chromosorb WHP 80-100 mesh size. However, complete separation between copper, nickel and palladium complexes was achieved on HPLC column (200 x 4.6 mm) Si 100, 5mu. The complexes were eluted with binary or ternary mixtures of chloroform, 1,2-dichloroethane and n-hexane. The detection by UV of each of the metal chelate was obtained at the ng levels.read more

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M Y KHUHAWAR ,A K TALPUR ,

IRON(III) CHELATES OF SOME SCHIFF-BASES DERIVED FROM ISATIN AND CHROMONE WITH SOME AMINO-ACIDS AND HYDRAZINE DERIVATIVES

Iron(III) complexes of the Schiff bases derived from isatin or chromone with glycine, beta-alanine, anthranilic acid, S-methyl hydrazine carbodithioate, ammonium salt of hydrazine carbodithioate, thiosemicarbazide, semicarbazide and benzoyl hydrazine were prepared and characterized by elemental analysis, IR, U.V.-vis spectra and magnetic measurements. Octahedral structures have been assigned to the prepared complexes.read more

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ALY M A HASSAAN ,

METAL-COMPLEXES OF COBALT(II), COPPER(II) AND NICKEL(II) WITH SOME DITHIOOXAMIDE DERIVED LIGANDS - THEIR SYNTHESIS, STRUCTURAL DETERMINATION AND ANTIBACTERIAL PROPERTIES

The complexes of cobalt(II), copper(II) and nickel(II) with some dithiooxamide derived ligands have been synthesised and characterised on the basis of their elemental analysis, molar conductance, magnetic moment, electronic, NMR and IR spectral data. These prepared complexes have been subjected to screening against bacterial species staphylococcus aureus. Escherichia coli, Klebsiella pneumoniae and Tuberculi bacilli. These studies have shown the metal complexes to be more antibacterial than those of the parent ligands.read more

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ABDUR RAUF ,ZAHID HUSSAIN CHOHAN ,

PREPARATION AND CHARACTERIZATION OF 2,2'-DIPYRIDYLAMINE, 2,2'-DIPYRIDYLKETONE AND 2,2'-DITHIODIPYRIDINE COMPLEXES OF CU(II), ZN(II), NI(II) AND U(VI) METAL-IONS

The neutral ligand (L) [where L = 2,2'-dipyridylamine (dpa), 2,2'-dipyridylketone (dpk) and 2,2'-dithiodipyridine (dtdp))] acts as bidentate electron donor to the metal. A methanolic solution of the metal salt MX2.nH2O [where M = Cu(II), Zn(II), Ni(II) and UO2(VI) and X = Cl, Br] reacts with the ligand (L) in (1:1) mole ratio to give complex of the type [ML X2] in association with or without the solvent molecule. However the salt Cu(II) when treated with (dpa) in (1:2) it yields the complex [Cu(dpa)2]X2 and with the ligand (dtdp) it yields only one type of the complex [Cu(dtdp)X2] even when a large excess of the ligand is used. All the complexes were characterized by their infrared spectra and elemental analyses. On the basis of infrared spectra it has been suggested that the ligands coordinate to the metal through the pyridine-N atoms. However the ligand (dpk) showed a low nuC = O stretching frequency indicating a direct interaction between the metal and the keto group of the ligand.read more

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M ISAHAQ ,M AL DOUSRY ,A O BAGHLAF ,A AL MOUTY ,

QUIONLINIUM CHLOROCHROMATE - A NEW REAGENT FOR CONVERSION OF PRIMARY AND SECONDARY ALCOHOLS TO CARBONYL-COMPOUNDS

The oxidation of a variety of primary and secondary alcohols including ethanol, 1-propanol, 2-propanol, 1-butanol, 2- butanol, 1-hexanol, 1-heptanol, cyclopentanol, cyclohexanol, benzyl alcohol, 2-chlorobenzyl alcohol, 1-phenyl-1-ethanol, 1-phenyl-1-propanol and furfuryl alcohol with quinolinium chlorochromate has been studied. As a result of oxidation, each primary alcohol yielded an aldehyde and each secondary alcohol yielded a ketone in reasonable yields. The reagent appears to be more effective for oxidation of aromatic and alicyclic alcohols as compared to oxidation of aliphatic alcohols.read more

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ABID RAFIQ AHMAD ,NASIM HASAN RAMA ,RASHID IQBAL ,

REACTION OF ACETYLENIC BETA-DIKETONES WITH SODIUM SULPHIDE

1,5-Diarylpent-1-yne-3,5-diones (1) reacted with sodium sulphide in 60% dioxane-water mixture at 15-degrees or fusion at 160-1700 to give a mixture of the corresponding 2,6-diaryl-4-pyrones (2) 4-thiones (3) and 5-aryl-2-benzylidene-3(2H)-thiophenethiones (4). The structure of the above compounds was confirmed from their spectral characteristics. The mechanisms for these transformations are discussed.read more

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MOHAMED GABER MAREI ,