VOLUME 12, NO4, DEC 1990

EXTRACTION - SPECTROPHOTOMETRIC DETERMINATION OF MOLYBDENUM (V) APPLICATION TO MOLYBDENITE ORE

A sensitive and modified method for the extraction and determination of the Mo(V) in the thiocyanate system has been developed. The orange red complex formed between Mo(V) and SCN is quantitatively extractable from an aqueous phase into an organic phase containing isobutyl alcohol. The complex gave maximum absorption at 470 nm and the system Obeys Beer's law in the range 0.01-7.0 ppm of molybdenum in the solution. The colour is stable for 24 hours and the molar absorptivity at 470 nm is 1.51 x 10(4)l mole-1 cm-1. The extractability of the complex by the tertiary alcohol suggests that the coloured species is anionic. Most of the common cations and anions do not interfere. The method developed was successfully applied to the analysis of molybdenite ores from Kohistan.read more

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HAROON AL RASHID ,TAJ ALI ,KAMIN KHAN ,

CIRCULAR-DICHROISM STUDIES ON SOME NON-RESOLVABLE MIXED-LIGAND COBALT(II) COMPLEXES

Circular Dichroism (CD) spectra of six mixed ligand complexes such as [Co(phen)2(bpy)]2+,[Co(phen)2gly]+,[Co(phen)2PyCA]+.[Co(bpy)2(phen)]2+ and [Co(bpy)2PyCA]+ (where phen = o-phenanthroline, bpy = 2,2' bipyridyl, gly = glycinate, PyCA = pyridine 2-carboxylate ion) in presence of different chiral environment compounds in aqueous media are reported. The CD spectra in presence of (+)-tartaric acid, (+)- malic acid and (+)-ascorbic acid consist of a positive band I between 20,408-20,740 cm-1 and a stronger, negative band II between 22,222-23,225 cm-1. A mirror image CD was obtained for these complexes in presence of (-)-tartaric acid and (-)-malic acid. The band I is assigned to electron excitation to 4A2 and band II to 4A1 upper states. The dextro enanthiomers of all these complexes have been assigned absolute DELTA-configuration around the metal ion.read more

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CHRISTY MUNIR ,A. ASGHIR ALAM ,NASIR AHMED ,M. DANISH ,

FORMATION OF MN-2+, CO-2+, NI-2+ AND CU-2+ COMPLEXES OF PARA-SUBSTITUTED BENZYLIDENE NICOTINYL HYDRAZONES

Two new series of [M(L)2(H2O)2] and [Mn(L)2(H2O)2]Cl2 complexes (M = Mn2+, Co2+, Ni2+ and Cu2+, L = monoaniomic bidentate ligands) have been prepared and characterised by DTA and TGA analysis. IR spectra indicated that the enolate oxygen and the C = N group are participating in complex formation in presence of metal(II) acetate, whereas the C = O group as well as the azomethine nitrogen are contributing to complex formation in presence of metal(II) chloride. Measurements of magnetic moments, ligand field and electron paramagnetic resonance spectra showed that Mn(II), Co(II) and Ni(II) exhibit octahedral geometry whereas Cu(II) ions display an axial elongated symmetry D 4b.read more

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M. GABER ,

CHEMICAL INVESTIGATION OF CEDRUS-DEODARA STEM-BARK .2. ISOLATION AND IDENTIFICATION OF SOME SESQUITERPENE HYDROCARBONS

G.C.M.S. studies showed that the pet.ether soluble fraction of Cedrus deodara bark has a large number of hydrocarbons. This paper describes the isolation and identification of saturated straight and branched chain hydrocarbons ranging C-14 - C20 and unsaturated sesquiterpene hydrocarbons with empirical formula C15H24. Four isomers of himachalene have been found. A new isomer with double bonds in a conjugated position 4 and 10, not reported before has been identified by its I.R, U.V., N.M.R. and mass spectra.read more

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S. NAHEED ,naeema khan ,

ELECTROCHEMICAL SYNTHESIS OF SOME HETEROCYCLIC MOLECULES IN AQUEOUS-MEDIA (1) LARGE-SCALE PREPARATIVE ELECTROLYSIS ON MERCURY POOL ELECTRODE

Practical hints for preparative electrolysis in aqueous media are reported together with the detailed experimental procedure for synthesis of some new heterocyclic moleculesread more

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H. M. FAHMY ,M. ABDEL AZZEM ,M. A. ABOUTABL ,

SYNTHESIS OF 3-(2-BENZIMIDAZOLYL)COUMARINES OF ANTICIPATED BIOLOGICAL-ACTIVITY

3-(2'-benzimidazolyl)-coumarines (5a-c) were synthesised through cyclocondensation of different o- hydroxyaldehydes with benzimidazole-2-acetonitrile (2). The reaction mechanism and the different spectral data were discussed as well as the biological results were evaluated.read more

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ALI S. EL-SAYED ,INAS E. ISLAM ,A. HAMMAD ,N. SHAFIK ,

SYNTHESIS OF SOME SUBSTITUTED CARBAMODITHIOIC ACID-ESTERS AND THEIR ANTIMICROBIAL ACTIVITIES

In this study seven new dithiocarbamate derivatives have been prepared by the reaction of 3-methyl-5-chloro-6-(2- bromopropionyl)-2-benzoxazolinone and substituted potassium dithiocarbamate derivatives. Their structures have been elucidated by UV, IR, NMR, MS and elementary analysis. The compounds synthesized have been assayed for their antifungal and antibacterial activities against various microorganisms.read more

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HAKKI ERDOGAN ,CIHAT SAFAK ,NURAN YULUG ,MEVLUT ERTAN ,

THERMODYNAMICS OF COMPLEXATION BETWEEN HALOALCOHOLS AND TETRAHYDROFURAN - AN INDIRECT APPROACH TO ASSESS INTRAMOLECULAR H-BONDING IN HALOALCOHOLS BY IR

The proton donor-acceptor complexes formed by 2-haloethanols with tetrahydrofuran in carbontetrachloride solution have been studied. The area of the OH-stretching band corresponding to the intermolecularly H-bonded complexes was plotted against concentration of the THF. From the shape of the curves the relative strength of the intramolecular H-bonds in 2-haloethanols appears to vary in the order F > Br > Cl > I. The anamoly in the relative strength of chloro and bromoethanol was checked from the results of complexes formed by 2-Cl and 2-Brethanol with triethylamine under similar conditions. The order obtained is in agreement to that in the case of THF.read more

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SHAHIDA SHAMIM ,MANSOOR AHMAD ,

SYNTHESIS OF SOME NEW DELTA-2-PYRAZOLINES, DELTA-2-ISOXAZOLINES AND 2-THIOPYRIMIDINE DERIVATIVES LIKELY TO POSSESS ANTIBACTERIAL ACTIVITY

Benzalacetophenone derivatives (1) were allowed to react with thiourea to give tetrahydropyrimidine thione (2) which by reaction with acyl hydrazine or p-chlorobenzoyl hydrazine gave triazolopyrimidines (4) and (5) respectively. Compounds (1) were reacted with hydrazylamine hydrochloride or hydrazines to give the corresponding DELTA-2-isoxazolines (8) and DELTA-2-pyrazolines (9) respectively. The constitution of the novel compounds were proved by microanalysis, IR and mass spectral data.read more

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G. ABD AL- LATIF ,S. EL BAHIE ,B. E. BAYOUMY ,M. EL MOBAYED ,

THE IMPACT OF SOLVENT-EXTRACTION ON THE RECOVERY OF MOLYBDENUM FROM MOLYBDENITE ORE

An investigation of the complex formed between molybdenum (VI) and hydrochloric acid has been carried out and its extractability by long chain high molecular weight amine (HMWA), Alamine 336 in organic solvent was examined. The chloro-complex formed is quantitatively extractable from an aqueous phase into the organic phase with tertiary amine. On the basis of this selective extractability a method has been developed for the extraction and recovery of Mo(VI). The effect of various diverse ions and certain other parameters was undertaken and discussed in order to explore the feasibility of the procedure for extracting molybdenum from various complex materials and ores.The extractability of the complex by HWMA indicates that the chloro-complex is anionic in nature. The method was applied successfully for the recovery of molybdenum from molybdenite ore. The exhausted HMWA was regenerated and used over and over again. The results obtained were encouragingread more

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KAMIN KHAN ,TAJ ALI ,