VOLUME 14, NO3, SEPT 1992

KINETICS OF OXIDATION OF METOL BY IODINE IN DIFFERENT ACIDS MEDIA

The kinetics or oxidation of metol ''N-methyl-p-aminophenol sulphate(1:2) ''by iodine dissolved in ethanol have been studied in acetic, hydrochloric, sulphuric and perchloric acids media and the oxidation reaction was found to be bimolecular. The rate of the reaction decreases with increase in the hydrogen ion concentration. The pseudo first order both with respect to metol and iodine has been found to be unity. The effects of concentration, acidity and temperature have been studied. The rate constants of the reaction (k), the pseude first order rate constants (k1), the activation parameters are also given and mechanism of the oxidation reaction has been suggested as well as.read more

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F A AL ISSA ,A A ALI ,

SPECTROSCOPIC STUDIES OF URINARY CALCULI IN THE SOLID-STATE

Two hundred renal calculi were analysed by pellet technique. Chemical composition of the outer shell and core of urinary calculi was determined separately wherever possible, otherwise the whole stone was powdered and analysed. The most frequently occurring components in both pure and mixed stones were calcium oxalate (whewellite/weddellite) (73.5%), uric acid (anhydrous/hydrated) (31%), apatite/whitlockite (20%), struvite (18%) and ammonium acid urate (7.5%). Calcium oxalate (37%), mixture of calcium oxalate and apatite/whitlockite (19%), and uric acid (19.4%) served as nuclei of urinary stones. Whitlockite did not occur in its pure state but its presence was detected in mixed form with calcium oxalate, struvite and apatite. Statistical combinations in relation to chemical composition of urinary calculi were computed and compared with the results of other workers. Calcium oxalate was the commonest component of pure as well as mixed stones. Only one stone was composed of cystine. Stones from children and factors such as sex, age, and environment have been discussed.read more

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H AHMED ,M IQBAL ,J AHMED ,M AFZAL ,

CIRCULAR-DICHROISM STUDIES OF SOME PFEIFFER ACTIVE MIXED-LIGAND CHROMIUM(III) COMPLEXES

Circular Dichroism (CD) spectra of a series of mixed ligand complex ions such as cis-[Cr(phen)2Cl2]+, [Cr(phen)2ox]+, cis-[Cr(bpy)2Cl2]+, [Cr(bpy)2gly]2+ and cis-(Cr(bpy)2(H2O)2]3+, (phen 1,10 phenanthroline, bpy 2,2'- bipyridyl, gly glycinate and ox oxalate ion) in presence of (+)-cinchonine HCl, (-)-cinchonidine HCl and (+)-tartaric acid have been studied. The CD spectra of these complexes in presence of(+)-cinchonine HCl and (+)-tartaric acid consist of two Cotton bands of opposite sign. The lower energy negative band I is observed between 16,667-16,949 cm-1 ([THETA] 0.5-11.9 deg.1.mole-1 cm-1). The higher energy positive band II is observed between 19,607-20,000 cm-1 ([THETA] 1.25-10.0 deg.1.mole-1 cm-1). These complexes have a mirror image spectra in presence of (-)-cinchonidine HCl. These CD bands have been assigned to electronic excitation to A1 and B2 upper states. The levo rotatory enantiomers of these complexes except [Cr(phen)2ox]+ enriched in presence of (+)-cinchonic HCl, have been assigned DELTA absolute configuration around the metal ion. The levo rotatory enantiomer of [Cr(phen)2ox]+ ion is enriched by (+)-cinchonine HCl and has (sic) absolute configuration.read more

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SYED RAUF ,CHRISTY MUNIR ,NASIR AHMED ,

AMINO-ACIDS CONTENT OF SEA SQUIDS

The protein content and amino acid composition of three species of sea squid Loligo duvaucellii, Sympleclotenllies oualaniensis and speciella inermis were determined very little qualitative and quantitative variation in amino acid profile was found among the various species studied. The essential amino acids were in a good balance compared with the FAO/WHO recommendations. The chemical score was 97 and the first limiting amino acid was valine.read more

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ALIA BANO ,SADIQA SHAKIR ,R B QADRI ,ASKARI BEGUM ,

SPECTROPHOTOMETRIC DETERMINATION OF BARBITURIC-ACID WITH SODIUM-NITRITE

A new and sensitive spectrophotometric method for determination of micro amounts of barbituric acid with sodium nitrite is described. The method is applicable in acidic medium (pH 4.7) in the concentration range of 4-1600 mug/ml of barbituric acid. The reported method can be used for determination of barbituric acid in presence of various barbiturates which do not interfere.read more

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RASHID IQBAL ,SHAHID M YOUSAF ,

PREPARATION, CHARACTERIZATION AND CHROMATOGRAPHIC STUDIES OF COPPER(II), NICKEL(II) AND OXOVANADIUM(IV) COMPLEXES OF NEW TETRADENTATE KETOAMINE SCHIFF-BASES

The copper(II), nickel(II) and vanadium(IV) complexes of bis(acetylmesityl oxide)-ethylenediimine (H-2AM2en), bis(acetylmesityl oxide) propylenediimine (H-2AM2pn), bis(acetylmesityl oxide) dl-stilbenediimine (dl-H2AM2S) and bis(acetylmesityloxide)meso-stilbenediimine (meso-H2AM2S) have been prepared and characterized using elemental analysis, IR, UV, H-1-NMR and mass spectroscopic techniques. The metal complexes were found insufficiently volatile for quantitative GC, and their nickel and copper complexes could only be eluted with detection limits at sub mug levels. However the copper, nickel and oxovanadium complexes are separated on a HPLC column Zorbax ODS (2 50 x 4.6 mm) with an ODS guard column. Complexes being eluted with 10% water in methanol, with detection limits at ng levels. Detection was achieved using a UV detector at 260 nm. Relative elution of nickel, copper and vanadium complexes on HPLC and GC columns indicated parallel results, with a decrease in retention with methyl substitution and an increase due to phenyl substitution at the bridge position.read more

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M Y KHUHAWAR ,A G BHATTI ,

A NUMERICAL APPROACH FOR DETERMINATION OF PARAMETERS FOR ION-EXCHANGE

The removal of boron from wastewaters containing boric acid and borax has been investigated. A boron-specific resin Amberlite XE 243 has been effective in removing boron. The experimental results obtained were evaluated both graphically and mathematically. The variation of boron concentrations in the effluents has been observed to depend, for various initial boron concentrations, Co on the ratio of filtrate volume to the volume accupied by resin. Consequently, an empirical equation relating effluent boron concentration, C to filtrate and resin volumes V and V1, respectively has been developed, resulting C = 2.34 . 10(-6). Co (V)-0.043. (V1)2.79read more

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SAMI SAHIN ,

HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATION OF COPPER(II), NICKEL(II) PALLADIUM(II) AND OXOVANADIUM(IV) COMPLEXES OF TETRADENTATE SCHIFF-BASES DERIVED FROM STILBENEDIAMINES

The nickel(II), palladium (11) and oxovanadium (IV) chelates of bis(acetylpivalyl-methane)meso-stilbenediimine(meso-H2APM2S), copper(II), nickel(II), palladium(II) and oxovanadium(IV) chelates of bis(acetylpivalylmethane)dl-stilbenediimine (dl-H2APM2S), bis-(isovalerylacetone)meso-stilbenediimine (meso-H2IV2S) and bis(isovaleroylacetone)dl-stilbene-diimine (dl-H2IVA2S) have been separated on reversed phase HPLC columns (250 x 4 mm) packed with Hypersil ODS 5mu and (150 x 3.9 mm) Nova Pak C-18 with guard ODS column. The copper, nickel, palladium and oxovanadium chelates of dl-H2IVA2S are also separated on normal phase HPLC column (250 x 4 mm) packed with licrosorb Si, 100 5mu. The detection is achieved using variable wavelength UV detector. The linear calibration range is observed at ng levels and detection limits at sub ng levels of metal chelates. Finally the effect of methyl and phenyl group substitution on the relative elution of copper, nickel and palladium chelates on Nova Pak C-18 column has been examined and evaluated.read more

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M Y KHUHAWAR ,ALTAF I SOOMRO ,

MONOBROMINATION OF AROMATIC RINGS USING POTASSIUM BROMIDE-SODIUM NITRATE MIXTURE IN SULFURIC-ACID

A simple and rapid method for the selective monobromination of aromatic rings involving the use of a mixture of potassium bromide and sodium nitrate in sulphuric acid (60% v/v) has been described.read more

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SAJID IQBAL ,M A MUNAWAR ,M SIDDIQ ,MASOOD ANWAR ,

SYNTHESIS OF BISPYRANOPYRAN-4,5-DIONES

Bispyranopyran-4,5-diones (2) have been prepared by the concomitant acetylation and cyclisation of bis-4-hydroxy-6-methyl-2H-pyran-2-ones (3) using a mixture of acetic anhydride and perchloric acid. Reactions of (2c) and (2d) with ammonium acetate afforded the corresponding bibpyridopyran-4,5-diones (4) while the hydrolysis of (2c) and (2d) with 20% aqueous sodium hydroxide gave bispyran-4-ones (5a) and (5b) respectively.read more

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M SIDDIQ ,A W KHAN ,