JSCS - Vol 63, No 9

J. Serb. Chem. Soc. 63(9) 677-683 (1998)
UDC 547.728/1/.2
JSCS-2573
Original scientific paper

Reactions of the hexachlorocyclodiphosphazanes withindanediones and 1-isobenzofuranones: Formation of indanedionylidene-, (isobenzofuranylidene)cyclodi-phosphazanes and indane-2-yl-, (phthalidyl)phosphoramidic chloride derivatives

M. R. SELIM, A. H. BEDAIR and F. M. EL-MASRY

Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr Sity, Cairo, Egypt

(Received 23 February 1998)
Reactions of hexachlorocyclodiphosphazanes (I) with indane-1,3-diones (II) afforded the geminal diaryl dichlorodiindane-1,3-dion-2-ylidene cyclodiphosphazane (IIIa-c), 2,4-dioxo-2,4-di(indane-2-yl)-1,3-diarylcyclodiphosphazane (Va,b), N-di(indane-2-yl)phosphinoaniline (VIa,b) and N-arylindanylphosphoramidic chloride (VIIIa,b). Also, analogous derivatives (Xa,b), (XI), (XIIa-d) from isobenzofuranone (IX) coupled with (I) were synthesised. The structure of the isolated products were confirmed by elemental analysis, UV, IR, ¹H-NMR and mass spectra results.

Key words: cyclodiphosphazanes, (indanedionylidene-, isobenzofuranylidene)cyclodiphosphazanes and (indanyl-, phthalidyl)phosphoramidic chlorides.

J. Serb. Chem. Soc. 63(9) 685-688 (1998)
UDC 547.455.643
JSCS-2574
Short communication

SHORT COMMUNICATION
An improved synthesis for obtaining 2-deoxy-2-iodo-D-mannopyranose derivatives

EVGENIJA DJURENDIC, NADA VUKOJEVIC*, TATJANA DRAMICANIN**, JANOS CANADI and DUSAN MILJKOVIC

Institute of Chemistry, Faculty of Science, University of Novi Sad, Trg Dositeja Obradovica 3, YU-21000 Novi Sad,
*Department of Organic Chemistry, Faculty of Pharmacy, University of Belgrade and
**Vinca Institute of Nuclear Sciences, Belgrade, Yugoslavia

(Received 6 April 1998)
The aim of this work was to synthesize 2-deoxy-2-iodo-manno sugars and 2-deoxy-2-iodo manno esters of a satisfactory purity in the highest possible yield. For this purpose, the iodination reaction of D-glucal triacetate (1), 3,4-di-O-acetyl-6-O-tosyl-D-glucal (2) and 3,4-di-O-acetyl-6-S-acetyl-6-thio-D-glucal (3) were investigated using a mixture of NaIO4-NaI at pH 6 (acetate buffer) and pH 7 (phosphate buffer) in a tert-butanol-water solvent system. Depending on the buffer system used, a mixture of the 2-deoxy-2-iodo-manno esters 4, 6 or 8 together with corresponding 2-deoxy-2-iodo sugars 5, 7, or 9 were obtained, or separately.

Key words: 2-deoxy-2-iodo-manno-sugars, iodination D-glucal derivatives, modified synthesis.

J. Serb. Chem .Soc. 63(9)689-692(1998)
UDC 547.92:547.594.4
JSCS-2575
Short communication

SHORT COMMUNICATION
An one-pot synthesis of syn-2,3-epoxyalcohols from a,b-unsaturated ketones

IRIS DJORDJEVIC and BOGDAN SOLAJA*

Faculty of Veterinary Medicine, University of Belgrade, Belgrade, and
*Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O.Box 158, YU-11001 Belgrade, Yugoslavia
E-mail:bsolaja@chem.bg.ac.yu

(Received 12 May 1998)
Facile one-pot synthesis of syn-2,3-epoxyalcohols from a,b-unsaturated ketones was achieved by consecutive addition of diisobutylaluminium hydride and t-butyl hydroperoxide.

Key words: reduction, epoxidation, diisobutylaluminium hydride, t-butyl hydroperoxide, syn-epoxyalcohols, steroid.

J. Serb. Chem. Soc. 63(9) 695-702 (1998)
UC 513.83:548.114:539.193
JSCS-2576
Original scientific paper

Relations between Wiener-type topological indices of plerograms and kenograms

IVAN GUTMAN and DUSICA VIDOVIC

Faculty of Science, University of Kragujevac, P.O.Box 60, YU-34000 Kragujevac, Yugoslavia

(Received 25 May 1998)
A plerogram (Pl) is a molecular graph in which all atoms are represented by vertices. A kenogram (Ke) is a molecular graph in which monovalent atoms (hydrogen and similar) are omitted. Recently, in the case of alkanes, a connection was established between Wiener-type topological indices (W_l) of plerograms and kenograms, of the form W_l (Pl) = aW_l(Ke) + b. In this work we determine the dependence of the coefficients a and b on the parameter l.

Key words: Wiener index, distance-based topological indices, molecular graph, plerogram, kenogram.

J. Serb. Chem. Soc. 63(9) 703-708 (1998)
UDC 546.171.1:536.7/.722
JSCS-2577
Original scientific paper

The simultaneous presentation of the thermodynamic properties of ammonia by the multiparameter Martin-Hou equation of state

SLOBODAN I. DJORDJEVIC, ALEKSANDAR Z. TASIC and BOJAN D. DJORDJEVIC

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, YU-11000 Belgrade, Yugoslavia

(Received 14 November 1997, revised 29 May 1998)
In this work, the simultaneous presentation of various thermodynamic properties: compressibility factor, residual enthalpy and residual heat capacity, of ammonia was performed over a broad range of temperature and pressure. The obtained results were analysed from the point of view of assessing the abilities of the Martin-Hou (MH) equation of state (EOS), which was critically selected for use in this work. The best results are presented and analysed along with the corresponding conclusions on the conditions of their use.

Key words: ammonia, thermodynamic properties, simultaneous presentation, high presure/temperature.

J. Serb. Chem. Soc. 63(9) 709-718 (1998)
UDC 666.322.4:66.081.3
JSCS-2578
Original scientific paper

The adsorption characteristics and porous structure of bentonite adsorbents, determined by the adsorption isotherm of water vapour

SNEZANA BREZOVSKA, VASA BOSEVSKA and DONCO BUREVSKI

Faculty of Technology and Metallurgy, University "St. Kiril and Metodij", Skopje, Macedonija

(Received 30 January 1998)
The adsorption characteristics of natural bentonite from Macedonia, monocationic Co²⁺-, Ni²⁺-, Cu²⁺-, Fe³⁺-, Al³⁺- and Zr⁴⁺ - bentonites and products obtained by acid activation of natural bentonite with 10, 15 and 20% solutions of HCl and H₂SO₄, have been analysed by means of adsorption isotherms of water vapour, using the BET equation. The different behavior of the monocationic bentonites during the adsorption process, is a consequence of the differences in the nature of the interlayer cations. The adsorption properties of natural bentonite are changed on treatment with either a solution of HCl or H₂SO₄, in terms of the adsorption of water vapour, especially the sample activated with HCl. The pore volumes of the examined bentonites were determined from the water vapour adsorption data using the Dubinin-Radushkevich equation. The results obtained from analysis of the adsorption isotherms on the natural, the acidoactivated and the monocationic bentonites show that three types of pores exist in the bentonite structures which are available for the adsorbate molecules on acid activaiton, the volume of the smaller pores reduces and the volume of the larger pores increases, as does the total volume of the pores, which is more noticeable in the case of the samples treated with the solutions of HCl. The total volume of the pores of the monocationic bentonites does not change importantly, but their distribution does.

Key words: adsorption, bentonite, chemical activation, ion exchange, Dubinin-Radushkevich equation.

J. Serb. Chem. Soc. 63(9)719-732(1998)
UDC 541.135.52/546.49/:543.253-543.47
JSCS-2579
Original scientific paper

A polarographic and voltammetric study of the surface phenomena at a mercury electrode in the presence of sulphur containing compounds

V. MIRCESKI, B. JORDANOSKI and M. AVRAMOV-IVIC*

Institute of Chemistry, Faculty of Natural Sciences, "St. Cyril and Methodius" University, P.O.Box 162, Skopje, Macedonia and *ICTM - Institute of Electrochemistry, University of Belgrade, Njegoseva 12, Belgrade, Yugoslavia

(Received 30 March, revised 24 June 1998)
The basic properties of the electrochemical behavior at a mercury electrode, of three sulphur containing drugs of different molecular structures, are described. Their electrode processes are studied by means of a classical DC polarography at a DME and a cyclic and square-wave voltammetry at a HMD electrode. The surface phenomena such as an adsoprtion as well as creation of a deposited film on the electrode surface of an insoluble salt, are discussed. It is demonstrated that a combination of the polarographic and voltammetric techniques provides sufficient information to elucidate the electrode mechanisms of the investigated compound, regarding the type of the surface phenomenons involved.

Key words: sulphur containing compounds, pharmacological activity, electrochemical activity, polarography, square-wave voltammetry, cyclic voltammetry, surface phenomena.

J. Serb. Chem. Soc. 63(9) 733-741 (1998)
UDC 546.34'35''36''':533.91:543.062
JSCS-2580
Original scientific paper

Determination of cesium, rubidium and lithium by stabilized DC arc plasma emission spectrometry

M. M. STOILJKOVIC, I. HOLCLAJTNER-ANTUNOVIC*, M. S. PAVLOVIC and B. B. RADAK

Vinca Institute of Nuclear Sciences, P.O.Box 522, YU-11001 Belgrade, and
*Faculty of Physical Chemistry, University of Belgrade, P.O.Box 137, YU-11001 Belgrade, Yugoslavia

(Received 7 April, revised 15 June 1998)
Optimization of the conditions for the analytical application of a vertical argon stabilized DC arc plasma, seeded by an easily ionizable element, potassium, is described. Such a plasma is used as an excitation source for the direct determination of Cs, Rb and Li. A high potassium chloride content in the solutions (of the order of 1%), significantly lowers the excitation temperature, which causes a suppression of the high energy processes (and of the corresponding spectral lines). The signal to background ratio of the moderate to low excitation potential lines increased by 10-100. Calibration was carried out under optimal conditions, and detection limits in the range 23.5 µg/dm³ to 0.055 µg/dm³ were reached, with linearity across 4-6 orders of magnitude. The method was successfully applied for the direct determination of Li, Rb and Cs in mineral water samples that, for comparison, were also analyzed by flame emission spectrometry. Good agreement between the two methods was achieved. The accuracy of the method was verified by the international reference standard SRM 1643d.

Key words: stabilized DC arc plasma, easily ionizable elements (EIE), atomic emission spectrometry, cesium, rubidium and lithium determination.

J. Serb. Chem. Soc. 63(9) 743-752 (1998)
UDC 547.828/54-53/:543.257.1
JSCS-2581
Original scientific paper

The persulphate-a,a'-dipyridyl system as indicator in theargentometric controlled-current potentiometric titrations

BILJANA F. ABRAMOVIC and FERENC F. GAAL

Institute of Chemistry, Faculty of Science, University of Novi Sad, Trg D. Obradovica 3, YU-21000 Novi Sad, Yugoslavia

(Received 8 April, revised 23 May 1998)
Starting from the voltammetric and controlled-current potentiometric study of the system persulphae-a,a’’’’’’'-dipyridyl in the presence and absence of silver(I), the same system was applied as indicator in the argentometric controlled-current potentiometric titrations of chloride, bromide, iodide, and thiocyanate. The possibility of using either one or two polarized platinum indicator electrodes was studied. The amounts of 0.6-6 mg of bromide, 0.1-10 mg of iodide, 4 mg thiocyanate and 2.6 mg of chloride were determined with relative standard deviations in the range from 0.2 to 1.1%. In general, the results show good agreement with those obtained by a comparative method.

Key words: persulphate-a,a' dipyridyl-silver(I) system, controlled-current potentiometric, argentometric titration, chloride, bromide, iodide, thiocyanate.

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