JSCS Vol 68, No. 10 

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J. Serb. Chem. Soc. 68(10)699–706(2003) UDC 542.913+547.78:541.8:535.342 JSCS – 3088 Original scientific paper

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Synthesis and investigation of solvent effects on the ultraviolet absorption spectra of 1,3-bis-substituted-5,5-dimethylhydantoins
 
GORDANA S. USCUMLIC, ABDULBASET A. KSHAD and DUSAN Z. MIJIN
 
Department of Organic Chemistry, Faculty of Technology and Metallurgy, University of Belgrade,
P. O. Box 3503, 11120 Belgrade, Serbia and Montenegro

(Received 17 March, revised 23 May 2003)
Abstract: A series of 1,3-bis-substituted-5,5-dimethylhydantoins was synthesized using the reaction of 5,5-dimethylhydantoin with the corresponding alkyl halide in the presence of trimethylAMine as catalyst and sodium hydroxide, according to a modified literature procedure. The experimental investigation included modification of the synthetic procedure in terms of starting materials, solvent, temperature, isolation techniques, as well as purification and identification of the products. The absorption spectra of the 1,3-bis-substituted-5,5-dimethylhydantoins were recorded in twelve solvents in the range 200–400 nm. The effects of the solvent polarity and hydrogen bonding on the absorption spectra were interpreted by means of linear solvation energy relationships using a general equation of the form n = n₀ + sp* + aa + bb and by two-parAMeter models presented by the equation n = n₀ + sp* + aa, where p* is a measure of the solvent polarity/polarisability, a is the scale of the solvent hydrogen bond donor acidities and b is the scale of the solvent hydrogen bond acceptor basicities. The solvent and substituent effects on the electronic absorption spectra of the investigated hydantoins is discussed.
 
Keywords: ultraviolet absorption spectra, solvent effects, linear solvation energy relationships, 1,3-bis-substituted-5,5-dimethylhydantoins.

J.Serb.Chem.Soc. 68(10)707–714(2003) UDC 547.92+542.913+548.735:66.099.73 JSCS – 3089 Original scientific paper

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Synthesis, crystal structure and antiaromatase activity of 17-halo-16,17-seco-5-androstene derivatives
 
KATARINA PENOV-GASI, SRDJAN STOJANOVIC, MARIJA SAKAC, EVGENIJA DJURENDIC, SUZANA JOVANOVIC-SANTA SLOBODANKA STANKOVIC*, NEBOJSA ANDRIC** and MIRJANA POPSAVIN
 
Department of Chemistry, Faculty of Science, University of Novi Sad, 21000 Novi Sad, Trg Dositeja Obradovica 3, (E-mail: marijas@ih.ns.ac.yu),
*Department of Physics, Faculty of Science, University of Novi Sad, 21000 Novi Sad, Trg Dositeja Obradovica 4 and
**Department of Biology, Faculty of Science, University of Novi Sad, 21000 Novi Sad, Trg Dositeja Obradovica 2, Serbia and Montenegro
 

(Received 14 April, revised 2 June 2003)
Abstract: Starting from 3b-acetoxy-15-cyano-17-oxo-16,17-seco-5-androstene (2) and 3b-acetoxy-15-cyano-17-hydroxy-17-methyl-16,17-seco-5-androstene (11), new 17-halo-derivatives (5–10 and 13) were obtained. The fluoro derivative 5 was obtained from 17-tosylate 4 in reaction with tetrabutylAMmonium fluoride. The structure of the 17-iodo-devitive 10 was unAMbiguously proved by the appropriate X-ray structural analysis. Compounds 5–10, as well as 12 and 13, were tested for possible anti-aromatase activity, whereby only compound 9, with bromine as the C-17 substituent, induced 19.4 % inhibition of aromatase activity compared to the control.
 
Keywords: 17-halo derivatives of 5-androstene, D-seco-steroids, aromatase inhibitors.

J.Serb.Chem.Soc. 68(10)715–718(2003) UDC 546.171+547–327:547.556.9 JSCS – 3090 Short communication

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 SHORT COMMUNICATION
 
FTIR study of N–H ^... p hydrogen bonding: N-alkylpropanAMides – aromatic donor systems
 
ALEKSANDAR D. NIKOLIC, MARKO R. MLADENOVIC*, LADISLAV GOBOR, DUSAN G. ANTONOVIC* and SLOBODAN D. PETROVIC*
 
Faculty of Natural Sciences and Mathematics, Trg Dositeja Obradovica 3, 21000 Novi Sad (E-mail: nikolic@ih.ns.ac.yu) and
*Faculty of Technology and Metallurgy, Karnegijeva 4, 11000 Belgrade, Serbia and Montenegro
 

(Received 3 December 2002)
This paper reports the results of an FTIR study in the region of the fundAMental NH stretching vibration for N-methyl, N-isopropyl, N-tert-butyl and N-1,2,2-trimethylpropanAMide – aromatic hydrocarbon systems. In addition to the spectroscopic parAMeters, the equilibrium constant for the 1:1 N–H ^... p complexes (at 298 K) are given.
 
Keywords: hydrogen bonding, N-monosubstituted AMides, aromatic hydrocarbons.

J.Serb.Chem.Soc. 68 (10)719–722(2003) UDC 577.164.1+66.095.12+547.81:66.097 JSCS – 3091 Short communication

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SHORT COMMUNICATION

VitAMin B12-catalyzed synthesis of some peracetylated alkyl b-D-xylopyranosides

ZORICA D. PETROVIC, DEJAN ANDJELKOVIC and LJILJANA STEVANOVIC
 
Department of Chemistry, Faculty of Science, University of Kragujevac, Radoja Domanovica 12, P. O. Box 60,
34000 Kragujevac, Serbia and Montenegro
 

(Received 28 March, revised 30 May 2003)
The vitAMin B₁₂-catalyzed glycosylation reaction of brominated b-D-xylose peracetate with alkanols ROH (C₁-C₈) has been studied. The catalytically active species in this reaction was cob(I)alAMin, obtained by chemical reduction of VitAMin B₁₂ with NaBH₄ (Co(III) to Co(I)). The reaction was carried out with 2 mol% of vitAMin B₁₂, with respect to xylosyl bromide 1, under argon at room temperature. Under these conditions, peracetylated C₁-C₈-alkyl b-D-xylopyranosides (3a–3f) were obtained in moderate yield (55–70 %). In all cases 3,4-di-O-acetyl-D-xylal (4) was obtained, as the product of reductive elimination of peracetylated xylosyl bromide (15–25 %).
 
Keywords: alkyl b-D-xylopyranosides; brominated b-D-xylose peracetate; glycosylaton; vitAMin B12.

J.Serb.Chem.Soc. 68(10)723–727(2003) UDC 547-304.6+547.853:536.75:66.022.362 JSCS – 3092 Short communication

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SHORT COMMUNICATION
 
A microwave-catalyzed rapid, efficient and ecofriendly synthesis of substituted pyrazol-5-ones
 
VIJAY V. DABHOLKAR and RAHUL P. GAVANDE
 
Department of Chemistry, Organic Research Laboratory, K. C. College, Mumbai - 400020, India
 

(Received 5 February, revised 7 May 2003)
A series of 1-(3,4-dihydro-3-oxo-2H-1,4-benzoxazine-2-carbonyl)-3-methyl-4-(substituted phenylhydrazono)-2-pyrazolin-5-ones have been synthesized by the reaction of 2H-3,4-dihydro-3-oxo-1,4-benzoxazine-2-carboxylic acid hydrazide with substituted acetoacetic ester derivatives using acetic acid as solvent under microwave irradiation (MWI), as well as by conventional methods. The reaction rate is enhanced tremendously and the yields are improved under MWI as compared to conventional methods.
 
Keywords: o-AMino phenol, 1,4-benzoxazine, hydrazine hydrate, 1,3,4-substituted pyrazol-5-one.

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J.Serb.Chem.Soc. 68(10)729–748(2003) UDC 547–304.6+547.853:536.75:66.022.362 JSCS – 3093 Original scientific paper

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Potentiometric and spectrophotometric studies of the complexation of Schiff-base hydrazones containing the
pyrimidine moiety
H. S. SELEEM*, B. A. EL-SHETARY, S. M. E. KHALIL and M. SHEBL
Chemistry Department, Faculty of Education, Ain ShAMs University, Roxy, Cairo, Egypt
 

(Received 26 November 2002, revised 7 May 2003)
Three Schiff-base hydrazones (ONN – donors) were prepared by condensation of 2-AMino-4-hydrazino-6-methylpyrimidine with 2-hydroxyacetophenone, 2-methoxybenzaldehyde and diacetyl to yield 2-OHAHP, 2-OMeBHP and DHP, respectively. The structures of these ligands were elucidated by elemental analysis, UV, IR, ¹H-NMR and mass spectra. The metal–ligand stability constants of Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, UO₂²⁺ and Th⁴⁺ chelates were determined potentiometrically in two different media (75 % (v/v) dioxane–water and ethanol–water) at 283, 293, 303 and 313 K at an ionic strength of 0.05 M (KNO₃). The thermodynAMic parAMeters of the 1:1 and 1:2 complexes were evaluated and are discussed. The dissociation constants of 2-OHAHP, 2-OMeBHP and DHP ligands and the stability constants of Co²⁺, Ni²⁺ and Cu²⁺ with 2-OHAHP were determined spectrophotometrically in 75 % (v/v) dioxane–water.
 
Keywords: stability constants, thermodynAMic parAMeters, spectrophotometric determination of stability, Schiff-base hydrazones containing the pyrimidine moiety.

J.Serb.Chem.Soc. 68(10)751–763(2003) UDC 546.65+547.543.2:543.42:543.57 JSCS – 3094 Original scientific paper

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Spectral and thermal behaviours of rare earth element complexes with 3,5-dimethoxybenzoic acid
 
WIESŁAWA FERENC, AGNIESZKA WALKÓW-DZIEWULSKA and JANUSZ CHRUŚCIEL*
 
Faculty of Chemistry, Maria Curie-Skłodowska University, PI 20-031 Lublin, Poland and
*Institute of Chemistry, University of Podlasie, PI 08-110 Siedlce, Poland, E-mail: wetafer@hermes.lublin.pl
 

(Received 14 February, revised 30 May 2003)
The conditions for the formation of rare earth element 3,5-dimethytoxybenzoates were studied and their quantitative composition and solubilities in water at 293 K were determined. The complexes are anhydrous or hydrated salts and their solubilities are of the orders of 10^-5 – 10^-4 mol dm^-3. Their FTIR, FIR and X-ray spectra were recorded. The compounds were also characterized by thermogravimetric studies in air and nitrogen atmospheres and by magnetic measurements. All complexes are crystalline compounds. The carboxylate group in these complexes is a bidentate, chelating ligand. On heating in air to 1173 K, the 3,5-dimethoxybenzoates of rare earth elements decompose in various ways. The hydrated complexes first dehydrate to form anhydrous salts which then decompose in air to the oxides of the respective metals while in nitrogen to mixtures of carbon and oxides of the respective metals. The complexes are more stable in air than in nitrogen.
 
Keywords: 3,5-dimethoxybenzoates, rare earth elements, thermal stability of 3,5-dimethoxybenzoates, magnetic properties of complexes.

J.Serb.Chem.Soc. 68(10)765–769(2003) UDC 546.19+541.8:543.23:543.4/.5 JSCS – 3095 Original scientific paper

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Kinetic determination of As(III) in solution
 
SOFIJA M. RANCIC, RANGEL P IGOV and TODOR G. PECEV
 
Department of Chemistry, Faculty of Science, University of Nis, 18000 Nis, Serbia and Montenegro
 

(Received 7 July 2002, revised 7 May 2003)
A new reaction is suggested and a new kinetic method is elaborated for the As(III) traces determination in solution, on the basis of their catalyzing effect on komplexon III (EDTA) oxidation by KMnO₄ in a strong acid solution (H₂SO₄). Using a spectrophotometric technique, a sensitivity of 72 ng/cm³ As(III) was achieved. The relative error of method varies from 5.5 to 13.9 % for As(III) concentration range from 83 to 140 ng/cm³. Appropriate kinetic equations are formulated and the influence of some other ions, including the As(V),  upon the reaction rate is tested.
 
Keywords: kinetic method, As(III) determination, EDTA, spectrophotometric technique.

J.Serb.Chem.Soc. 68(10)771–777(2003) JSCS – 3096 UDC 54–72.001.57:541.135.2:546.56–034.3 66.011:54–72:546.56–034.3 Original scientific paper

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The effect of the particle shape and structure on the flowability of electrolytic copper powder. I. Modeling of a representative powder particle

KONSTANTIN I. POPOV¹, SNEŽANA B. KRSTIĆ¹, MILUTIN Č. OBRADOVIĆ¹, MIOMIR G. PAVLOVIĆ²,
LJUBICA J. PAVLOVIĆ² and EVICA R. IVANOVIĆ³

¹Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade,
²ICTM -Department of Electrochemistry, Njegoševa 12, 11000 Belgrade
³Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11080 Zemun-Belgrade, Serbia and Montenegro
(E-mail: kosta@elab.tmf.bg.ac.yu)

(Received 10 March 2003)

One of the most important properties of copper powder is its flowability which depends on the shape and the structure of the powder particles.Aprocedure for the determination of a representative powder particle permitting the free flow of copper powder is proposed.

Keywords: copper powder flowability, representative particle of flowing powder, surface structure of particles of flowing powder.

J.Serb.Chem.Soc. 68(10)779-783(2003) JSCS - 3097 UDC 54-72.001:541.135.2:546.56–034.3 001.818:66.011:54-72:546.56-034.3 Original scientific paper

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The effect of the particle shape and structure on the flowability of electrolytic copper powder.
II. The experimental verification of the model of the representative powder particle

KONSTANTIN I. POPOV¹, MIOMIR G. PAVLOVIĆ², LJUBICA J. PAVLOVIĆ² ,EVICA R. IVANOVIĆ³,
SNEŽANA B. KRSTIĆ¹ and MILUTIN Č. OBRADOVIĆ¹,

¹Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade,
²ICTM -Department of Electrochemistry, Njegoševa 12, 11000 Belgrade
³Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11080 Zemun-Belgrade, Serbia and Montenegro
(E-mail: kosta@elab.tmf.bg.ac.yu)

(Received 10 March 2003, revised 27 May 2003))

An analysis of the effects of the shape, surface structure and size distribution of particles on the flowability of the copper powder was performed. It is shown that the most important property of the particles of a powder, regarding the flowability of the powder, is the surface structure of the particles.

Keywords: copper powder flowability, surface structure of particles of a flowing powder.