JSCS - Vol 63, No3

J.Serb.Chem.Soc. 63(3)165-169(1998)
JSCS-2520
UDC 547.789/.79
Original scientific paper

Regioselective synthesis of novel ethyl Z-and
E-2-alkylidene-4-oxothiazolidine-5-acetate derivatives

RADE MARKOVIC and MARIJA BARANAC*

Faculty of Chemistry, University of Belgrade, Studenski trg 16, P.O.Box 158, 11001 Belgrade, and Center for Chemistry ICTM, P.O.Box 815, Belgrade and
*Faculty of Pharmacy, Department of Organic Chemistry, University of Belgrade, P.O.Box 146, YU-11224, Belgrade, Yugoslavia

(Received 24 Octobar, revised 13 December 1997)
The syntheses of the title compounds containing an exocyclic double bond of exclusively the Z-configuration, via the regioselective base catalyzed reacation of the nitrile precursors possessing an acidic a-hydrogen with diethyl 2-mercaptobutanedioate in anhydrous ethanol, are described. The ¹H-NMR data indicating the presence of both geometrical isomers in primarily nonpolar media favoring the E-form, are presented in terms of the solvent influence on intra-and intermolecular H-bonding and sterochemical outcome of the reaction.

Key words: 4-oxothiazolidine derivatives, oxocyclic double bond, H-bonding.

J.Serb.Chem.Soc. 63(3)171-182(1998)
JSCS-2521
UDC 547.728.2:542.9:615.779.15
Original scientific paper

Preparation, crystal sstructure and antibactaerial activity of condensation
products of usnic acid and acyl hydrazides

DUSAN SLADIC, VLADIMIR BELJANSKI, BOGDAN PRELESNIK, GORAN
BOGDANOVIC*, IVANA IVANOVIC and KATARINA ANDJELKOVIC

Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O.Box 158, YU-11001 Beograde and
*Laboratory of Theoretical Physics and Physics of Condensed Matter, Vinca Institut of Nuclear Science, P.O.Box 522, YU-11001 Belgrade, Yugoslavia

(Received 20 October, revised 13 Decembar 1997)
Three condensation products of usnic aacid with the hydrozides of a-naphthoic, caprylic, and oxamic acids, respectively, have been prepared and characterized by spectrometric methods. A reassignment of the ¹³C-NMR spectral data of usnic acid has been done. The crystal structure of usnic acid 11-[(1-naphthoyl)hydrazone] ethanol solvate (1:1) has been determined. This substance crystallizes in the monoclinic crystal system, the space group P2₁, with the unit cell dimensiones a = 0.77365(7)nm, b = 0.9632(2)nm, c = 0.94150(15)nm, b = 108.830(11), V = 1.4050 (4) nm³, and Z = 2. At the end of the structureanalysis R = 0.055, R_w= 0.052 and S = 0.89. The antibacterial activities of the compounds have been evaluated. The greatest activity against Staphylococcus aureus was found for usnic acid, somewhat lower for the derivatives with hydrazides of a-naphthoic and caprylic acid, and much lower for the derivative with semioxamazide. The activities of these compounds probably depend on their lipophilicity.

Key words: usnic acid derivatives, acyl hydrazides, biological activity, crystal structure, NMR spectra.

J.Serb.Chem.Soc. 63(3)183-187(1998)
JSCS-2522
UDC 623.458/611.8/:546.212/66.062-546.212
Short communication

SHORT COMMUNICATION
The distribution coefficients of 1,2,2-trimethylpropyl-methylfluorophosphonate between some organic solvents and water

ZORAN T. LUKOVIC, BRANISLAV Z. JOVANOVIC* and NIKOLA K. BOCVAROV

Military Technical Institute, Kataniceva 15, Belgrade and
*Department of Organic Chemistry, Faculty of Technology and Metallurgy, Karnegijeva 4, YU-11000 Belgrade, Yugoslavia

(Received 13 June, revised 18 November 1997)
The results of determining the distribution coefficient (K_o) of 1,2,2-trimethylpropyl-methylfluorophosphonate (soman) between some organic solvent and water at 25°C are presented. A linear dependance between log K_o of soman and other chsen Chemical warfare agents (CWA's) was established with changing cohesivity parameters of the organic solvents (b_coh).

Key words: distribution coefficients, soman solubility parameters, cohesivity parameters.

J.Serb.Chem.Soc. 63(3)191-192(1998)
JSCS-2523
UDC 547.821.2:6.15.35
Note

NOTE
Rearrangement of some steroidal a,b-unsaturated puridine-N-oxides and
antiandrogenic activity of obtained compounds

KATARINA PENOV-GASI, MARIJA SAKAC, EVGENIJA DJURENDIC,
RADMILA KOVACEVIC* and SOLVANA ANDRIC*

Institute of Chemistry, Faculty of Sciences, Trg D.Obradovica 3, 21000 Novi Sad, Yugoslavia,
*Institute of Biology, Faculty of Sciences, Trg D.Obradovica 3, 21000 Novi Sad, Yugoslavia

(Received 18 June, revised 23 November 1997)
Rearrangement of steroidal a,b-unsaturated pyridine-N-oxides 1 and 2 with acetic anhydride afforded diasteroisomeric 20-acetoxy-17-picolyl-16-androstene derivatives 3,4,5 and 6. A method for separating the obtained stereoisomeric acetates 5 and 6 via the corresponding diols 7 and 8 was developed. X-Ray structural analysis of diol 7 unambiguously proved its 20(S)-configuration. Compounds 2,5-8 were tested in vitro, as possible inhibitors of androgen biosynthesis at the level of steroidogenic enzymes.

Key words: derivatives of 5-androstene, steroidal N-oxides, rearrangement, antiandogenic activity.

J.Serb.Chem.Soc. 63(3)195-199(1998)
JSCS-2524
UDC 547.415.1/546.733-54-386/
Original scientific paper

Synthesis and characterization of uns-cis-(ethylenediamine-N,N'-di-3-propionato)
cobalt(III) complexes with symmetrical b-diketonato ligands

TIBOR J. SABO, SANJA R.GRGURIC, ZIVOSLAV Lj.TESIC and
SRECKO R. TRIFUNOVIC*

Faculty of Chemistry, University of Belgrade, P.O.Box 158, 11001 Belgrade and
*Faculty of Science, Department of Chemistry, University of Kragujevac, P.O.Box 60,
34000 Kragujevac, Yugoslavia

(Received 2 October, revised 28 November 1997)
Some uns-cis-(ethylendiamine-N,N'-di-3propionato)cobalt(III) complexes with symmetrical b-diketonato ligands, 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione and 2,2,6,6-tetramethyl-3,5-heptanedione, have been prepared by the reaction of sodium uns-cis-(ethylenediamine-N,N'-di-3-propionato)(carbonato)cobaltate(III) and the corresponding diketone at 75°C. The complexes were isolated chromatographicaly and characterized by elemental analysis, infrared and electron adsorption spectroscopy.

Key words: cobalt(III) complexes, ethylenediamine-N,N'-di-3-propionic acid, diketonates.

J.Serb.Chem.Soc. 63(3)201-212(1998)
JSCS-2525
UDC 546.98'74''-541.135.52:546.11(66.071)
Original scientific paper

Unconventional temperature-dependence of Tafel slopes for the hydrogen
evolution reaction at Pd-Ni electrode in alkaline solution

Lj. VRACAR, S.BUROJEVIC* and N.KRSTAJIC

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, YU-11000 Belgrade and
*Faculty of Chemistry, University of Belgrade, Studentski trg 16, YU-11000 Belgrade, Yugoslavia

(Received 24 October, revised 17 December 1997)
Cathodic polarization for the hydrogen evolution reaction at a Pd-Ni electrode in alkaline solution have been measured in the temperature range 278-348 K. The polarization behaviour has been evaluated and the exchange current densities, Tafel slopes as a function of temperature and apparent enthalpies of activation as a function of potential have been determined. The Tafel slope behaviour as a function of temperature has been analyzed to give the formal enthalpic (a_H) and entropic (a_C) components of the transfer coefficient or, for certain conditions, the symmetry factor for charge transfer. Potential-relaxation experiments, following interruption of the cathodic polarization currents, enable the pseudocapacitance (C_F), for the H sorption, as a function of potential, to be evaluated. These results suggest that the H₂ evolution reaction takes place through proton discharge on the surface covered by H a with constant coverage which is one of the requests for Tafel slope temperature dependence analysis.

Key words: hydrogen evolution, charge transfer, symmetry factor, Tafel slope.

J.Serb.Chem.Soc. 63(3)213-218(1998)
JSCS-2526
UDC 543.432:543.8/546.212/
Original scientific paper

Colorimetric method for semiquantitative determination of
chloroorgannics in water

SLAVICA M. STEVANOVIC, MIRJANA DAMLJANOVIC and MILAN V. MITROVIC*

Department of Analytical Chemistry, Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, P.O.Box 494, YU-11000 Belgrade and
*Institute of General and Physical Chemistry, YU-11000 Belgrade, Yugoslavia

(Received 12 August 1997)
An adsorption method for the semiquantitative determination of very low concentrations of chloroorganics in water is described. The dissolved chloroorganics were concentrated from very dilute aqueous solutions by means of isothermal equilibrium adsorption on an adsorbent (silcia gel, Al₂O₃, silica gel + Al₂O₃(1:1) of limited surfaces area which was, by a special process, given the form of a porous film. Using visualization reagents (AgNO₃ + bromophenol blue or rhodamine B), wisibly coloured surface were obtained which, by direst colorimetric measurements in diffusely reflected light, using a reference curve, can be applied for the determination of unknown concentrations. The concentration range investigated was in the interval from 0.01 to 10 mg dm^-³ of hezachlorocyclohexane (lindane ) in water (pH ranging from 1 to 12).

Key words: chloroorganics, lindane, equilibrium adsorption, reflected light colorimetry.

J.Serb.Chem.Soc. 63(3)219-230(1998)
JSCS-2527
UDC 666.1.036.4:62.001.57/.573
Original scientific paper

Modeling of drawing thin glass sheet from a preform

ALEKSANDRA MILUTINOVIC-NIKOLIC, RADMILA JANCIC* and RADOSLAV ALEKSIC*

Institut of Chemistry, Technology and Metallurgy, Njegoseva 12, P.O.Box 815, YU-11001 Belgrade and
*Faculty of Technology and Metallurgy, Karnegijeva 4, P.O.Box 494, YU-11001 Belgrade, Yugoslavia

(Received 14 October 1997)
A one-dimensional model of thin glass shet drawing has been developed. This model includes momentum, heat and mass balance equations. The density, viscosity and specific heat of the glass were calculated as functions of temperature, and the glass emissivity was defined and calculated as a function of both temperature and glass thickness. After allowed simplifications, two ordinary differential equations were obtained and solved using the Runge Kutte method. The model was used to investigate the influence of different process parameters (the velocity of lowering the preform into the furnace, the axial temperature profile of the furnace, the drawing force and its direction etc.) on the change in the shape of the drawn glass sheet for different glass compositions and vaious geometrical characteristics of the preform. A laboratory device for drawing thin glass sheets from rectangular preforms enabled full control of the process parameters, their measurement, as well as data acquisition. The results of the numerical simulation were compared with the experimental data and good agreement between them was found.

Key words: glass, glass drawing, modeling.

J.Serb.Chem.Soc. 63(3)321-235(1998)
JSCS-2528
UDC 546.78/621-426/:621.785.5:549.211
Note

NOTE
Conditioning of the filament for diamond deposition by hot-filament
chemical vapour deposition method

GORDANA S. RISTIC*, LJUBICA T. PETKOVSKA*, ZARKO D. BOGDANOV*,
SLAVICA ZEC*, SCEPAN S. MILJANOVIC*'**

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

(Received 12 August, revised 21 November 1997)
Tungsten filament, 0.12 mm in diameter, was conditioned by heating in a mixture of methane and hydrogen of three different concentration ratios. The filament was heated by an electric current. The procedure was carried out stepwise keeping either the voltage of the temperature of the filament constant. Changes in the filament material were monitored by resistance and temperature measurements. The chemical composition was checked using X-ray diffraction (XRD) analysis. The final state of the filament was investigated and photographed using the scanning electron microscopy (SEM) technique.

Key words: hot-filament, conditioning, carburization, diamond deposition, hfCVD.

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