JSCS Vol 72, No. 1

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J. Serb. Chem. Soc. 72 (1) 1–3 (2007)
UDC 929 "Dragutin Dražić" + 025.326 + "Journal Serbian Chemical Society"

DRAGUTIN M. DRAZIC
Editor of 21 volumes of the Journal of the Serbian Chemical Society (1986-2006)

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J. Serb. Chem. Soc. 72 (1) 5–11 (2007)
UDC 547.772:616.982:615.281/.282: JSCS–3529; doi: 10.2298/JSC0701005Y; Original scientific paper

Synthesis and antimycobacterial activity of novel heterocycles
M. SHAHAR YAR, A. AHMAD SIDDIQUI and M. ASHRAF ALI
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, JAMia HAMdard (HAMdard University), New Delhi-110062, India

(Received 21 December 2005, revised 10 May 2006)
In the present investigation 4-hydroxy-3-methylacetophenone on condensation with various aromatic aldehydes in methanolic KOH solution yielded the corresponding chalcones (C_I–C_XI). These chalcones were further reacted with hydrazine hydrate in ethanol which led to the formation of pyrazoline derivatives (H_I–H_XI). The newly synthesized heterocyles were characterized on the basis of their chemical properties and spectroscopic data. All newly synthesized compounds were evaluated for their antimycobacterial activities against Mycobacterium tuberculosis H37_Rv.

Keywords: pyrazoline, antimycobacterial, Mycobacterium tuberculosis.

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J. Serb. Chem. Soc. 72 (1) 13–27 (2007)
UDC 542.913+665.75.000.57:547.426.23+547.261; JSCS–3530; doi: 10.2298/JSC0701013G; Original scientific paper

Vapor–liquid equilibria of triglycerides–methanol mixtures and their influence on the biodiesel synthesis under supercritical conditions of methanol
SANDRA GLISIC, OSCAR MONTOYA*, ALEKSANDAR ORLOVIC, DEJAN SKALA
Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, P. O. Box 3503, 11120 Belgrade, Serbia
*Department of Chemical Engineering, National University of Columbia, Bogota D. C., Avendida Carrera 30 No 45-03, Columbia

(Received 10 January, revised 4 May 2006)
The non-catalytic synthesis of biodiesel (fatty acids methyl esters) from triglycerides and methanol proceeds at elevated pressures above 100 bar and temperatures above 523 K. Kinetic investigations of the system revealed an unusual behavior of the reaction rate constant with increasing temperature and pressure. In order to explain this phenomenon, the phase behavior of the triglycerides–methanol mixture was investigated. The phase equilibria of the binary system sunflower oil–methanol were measured at different temperatures between 473 and 503 K, and a range of pressures between 10 and 56 bar. The experimental data were correlated using the Peng–Robinson, Soave–Redlich–Kwong and Redlich–Kwong–Aspen equations of state and different mixing rules. The best results were obtained with the RK–ASPEN equation of state and the Van derWaals mixing rule (VdW), which were then used to calculate the distribution of the phases at pressures and temperatures usual for the non-catalytic synthesis of biodiesel under high pressures. The obtained data indicated a strong influence of the phase equilibria on the reaction kinetics.

Keywords: vapor–liquid equilibria, high pressure, supercritical conditions, binary interaction parAMeters, biodiesel synthesis.

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J. Serb. Chem. Soc. 72 (1) 29–35 (2007)
UDC 547.581.9+543.4/.5:615.014.2; JSCS–3531; 10.2298/JSC0701029K; Original scientific paper

Spectrophotometric determination of thioctic (a-Aipoic) acid in water and pharmaceutical preparations
ZAGORKA KORI]ANAC, MIRA CAKAR, SLADJANA TANASKOVIC and TATIJANA JOVANOVIC
Faculty of Pharmacy, University of Belgrade, P. O. Box 146, Vojvode Stepe 450, 11000 Belgrade, Serbia

(Received 28 December 2005, revised 30 May 2006)
A spectrophotometric method is described for the assay of thioctic acid. The method is based on the reaction between the drug and palladium(II) chloride. In this reaction, a yellow-coloured, water soluble product with a 1:1 stoichiometric ratio and an absorption maximum at 365 nm was formed. The stability of the formed complex depends on various factors (pH, reaction time, concentration of reagents, ionic strength). Based on these findings, a new method is suggested for the spectrophotometric determination of thioctic acid in pharmaceutical formulations. This
method is simple, sensitive and reproducible.

Keywords: thioctic acid, spectrophotometric determination, injection solutions and tablets.

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J. Serb. Chem. Soc. 72 (1) 37–44 (2007)

UDC *carvedilol+66.092:541.143; JSCS–3532; 10.2298/JSC0701037S; Short communication

Monitoring of the photochemical stability of carvedilol and its degradation products by the RP-HPLC method

JELENA STOJANOVIC, SOTE VLADIMIROV*, VALENTINA MARINKOVIC, DRAGAN VELICKOVIC, PREDRAG SIBINOVIC

Zdravlje Actavis Company, Pharmaceutical and Chemical Industry, Quality Control Department, Leskovac, Serbia

*Faculty of Pharmacy, Department of Pharmaceutical Chemistry, Belgrade, Serbia

(Received 24 October 2005, revised 12 April 2006)

A sensitive, selective, precise and stability-indicating, new high-performance liquid chromatographic method for the analysis of carvedilol both as a bulk drug and in formulations was developed and validated. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. The method was validated for linearity, selectivity, precision, robustness, LOD, LOQ and accuracy. The chromatographic separation was achieved on a Chromolit RP8e, 100 ´ 4.6 mm, analytical column. The mobile phase consisted of a mixture of acetonitrile and water (45:55, V/V) (pH 2.5), pH adjusted with formic acid. The absorbance was monitored with a UV detector at 280 nm and the temperature of the analyses was 40 °C. The flow rate was 0.5 mL/min. The linearity (r ³ 0.999), reproducibility (0.68–1.27 %) and recovery (99.71–101.58) were found to be satisfactory. This method enables the simultaneous determination of carvedilol and its degradation products, as well as stability.

Keywords: carvedilol, 4-hydroxycarbazole, RP-HPLC, stability.

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J. Serb. Chem. Soc. 72 (1) 45–53 (2007)

UDC 669–492.2/.3–034.3+621.927:621.78:537.31; JSCS–3533; doi: 10.2298/JSC0701045R; Original scientific paper

The properties of high-energy milled pre-alloyed copper powders containing 1 wt. % Al

VISESLAVA RAJKOVIC, DUSAN BOZIC and ALEKSANDAR DEVECERSKI

Vinca Institute of Nuclear Sciences, P. O. Box 522, 11001 Belgrade, Serbia

(Received 30 November 2005, revised 2 April 2006)

The microstructural and morphological changes of inert gas atomized pre-alloyed Cu-1 wt. % Al powders subjected to hith-energy milling were studied. The microhardness of hot-pressed compacts was measured as a function of milling time. The thermal stability during exposure at 800 °C and the electrical conductivity of compacts were also exAMined. During the high-energy milling, severe deformation led to refinement of the powder particle grain size (from 550 nm to about 55 nm) and a decrease in the lattice parAMeter (0.10 %), indicating precipitation of aluminium from the copper matrix. The microhardness of compacts obtained from 5 h-milled powders was 2160 MPa. After exposure at 800 °C for 5 h, these compacts still exhibited a high microhardness value (1325 MPa), indicating good thermal stability. The increase of microhardness and good thermal stability is attributed to the small grain size (270 and 390 nm before and after high temperature exposure, respectively). The room temperature electrical conductivity of compacts processed from 5 h-milled powder was 79 % IACS.

Keywords: Cu-1 wt.% Al pre-alloyed powders, high-energy milling, grain size, hardening, electrical conductivity.

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J. Serb. Chem. Soc. 72 (1) 55–62 (2007)

UDC546.815'24'711+546.815'24'22:535.004.12:543.4; JSCS–3534; doi: 10.2298/JSC0701055T; Original scientific paper

Pb_1-xMn_xTe and PbTe_1-xS_x compounds and their optical properties

JELENA TRAJIC, ALEKSANDAR GOLUBOVIC, MAJA ROMCEVIC, NEBOJSA ROMCEVIC, SLOBODANKA NIKOLIC and VLADIMIR N. NIKIFOROV*

Institute of Physics, Pregrevica 118, P. O. Box 68, 11080 Zemun, Serbia

*Low-temperature Physics Department, Moscow State University, 119899 Moscow, Russia

(Received 7 December 2005, revised 6 April 2006)

Pb1-xMnxTe crystals were obtained by the Bridgman method and PbTe1-xSx crystals were grown by the vapour–liquid–solid technique. The tructural properties of Pb_1-xMn_xTe (x £ 0.10) and PbTe_1-xS_x (x £ 0.05) were observed by X-ray powder diffraction analysis. The optical properties were studied by RAMan spectroscopy as a function of temperature. Measurements on these sAMples of different composition gave information about the Mn and S position in the lattice (off-centering), their clustering and ordering, as well as of the influence of these processes on the crystal structure and properties. The model of phonon behaviour based on the Random Element Isodisplacement model was applied, and it was found that the phonons in PbTe_1-xS_x show a two-mode behaviour (each TO-LO mode pair of the end members degenerates to an impurity mode), while the Pb_1-xMn_xTe optical phonons have a ntermediate one-two-mode behaviour (the LO-mode frequency shifts continuously from PbTe to MnTe, while the other modes resemble the two-mode case).

Keywords: lead manganese telluride, lead telluride sulphide, structural properties, RAMan spectroscopy.

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J. Serb. Chem. Soc. 72 (1) 63–71 (2007)

UDC 547.821+547.576+547.288.3+546.733:548.7:54.06; JSCS–3535; doi: 10.2298/JSC0701063B; Original scientific paper

Crystal structure of tris(pyridine)(salicylaldehyde semicarbazonato(2-))cobalt(III)-trichloropyridinecobaltate(II) at 293 and 120 K

GORAN A. BOGDANOVIC, VUKADIN M. LEOVAC*, LJILJANA S. VOJINOVIC-JESIC*, ANNE SPASOJEVIC-DE BIRÉ**

Vinca Institute of Nuclear Sciences, Laboratory of Theoretical Physics and Condensed Matter Physics, P. O. Box 522, 11001 Belgrade, Serbia,

*Department of Chemistry, Faculty of Science, University of Novi Sad, Trg Dositeja Obradovi}a 3, 21000 Novi Sad, Serbia

**Laboratoire de Structures, Propriétés et Modélisation des Solides, (SPMS), UMR 8580 du CNRS, Ecole Centrale Paris, Grande Voie des Vignes 92295 Chãtenay-Malabry Cedex, France

(Received 15 November 2005, revised 14 May 2006)

The crystal structure of [Co^III(L)(py)₃][Co^IICl₃(py)[ (H₂L = salicylaldehyde semicarbazone)was determined by X-ray analysis based on two single crystal X-ray experiments performed at 120 K and 293 K, respectively. It was found that the pyridine ligand of the complex anion is disordered over two positions. The preferential position of this pyridine found at120Kwas explained in terms of the C–H...Cl intermolecular interaction between the tetrahedral [Co^II(py)Cl₃]^- anions. The mer-octahedral geometry of the cation in the presented crystal structure was compared with previously published structures of similar composition, [Co^III(L¹)(py)₃]+[Co^IICl₃(py)]^-·EtOH and [Co^III(LI)(py)₃]+I₃^- (H₂L^I = salicylaldehyde S-methylisothiosemicarbazone). Although the tetrahedral [Co^IICl₃(py)]^- anions possess the sAMe charge, they mutually form different intermolecular interactions which can be realized either by C–H...Cl hydrogen bonds or by p-p interactions between the pyridine rings.

Keywords: Co(III) complexes, salicylaldehyde semicarbazone, crystal structure, low temperature X-ray experiment, disordered crystal structure.

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J. Serb. Chem. Soc. 72 (1) 73–80 (2007)

UDC 635.74+664.1.035:547.972.2/.3+547.962.6; JSCS–3536, doi: 10.2298/JSC0701073V; Original scientific paper

Extraction of flavonoids from garden (Salvia officinalis L.) and glutinous (Salvia glutinosa L.) sage by ultrasonic and classical maceration

DRAGAN T. VELICKOVIC, MILENA T. NIKOLOVA*, STEPHANIE V. IVANCHEVA*, JELENA B. STOJANOVIC and VLADA B. VELJKOVIC

Zdravlje-Actavis Company, 199 Vlajkova St., 16000 Leskovac, Serbia

*Institute of Botany, Bulgarian Academy of Sciences, 23 G. Bunchev St., 1113 Sofia, Bulgaria

**Faculty of Technology, 124 Bulevar oslobo|enja St., 16000 Leskovac, Serbia

(Received 2 December 2005, revised 10 May 2006)

Flavonoids were analysed in the extracts of garden (Salvia officinalis L.) and glutinous (Salvia glutinosa L.) sage. Ultrasonic extraction (20 minutes at 40 °C) and classical maceration (6 h at room temperature) of the extractable substances from dried herbs and dried residual plant materials from which the essential oil had previously been removed by hydrodistillation were performed with petroleum ether, 70 % aqueous solution of ethanol and water. It was found that the extracts from both plants contained flavonoids, but their compositions were dependent of the plant species, the polarity of the extracting solvent and the extraction technique applied. Apigenin and its derivatives (e.g., apigenin 4'-methyl ether), scutellarein 6-methyl ether, isoscutellarein 8-methyl ether, luteolin and 6-OH-luteolin-6-methyl ether where distinctive for S. officinalis. Apigenin, luteolin, 6-OH-luteolin-6-methyl ether, kaempherol 3-methyl ether, kaempherol 3,7-dimethyl ether, quercetin 3,7,3'-trimethyl ether and quercetin 3,7,3',4'-tetrAMethyl ether were distinctive for S. glutinosa. The flavonoids were also detected in considerable quantities in the plant material from which the essential oils had been already removed. Hence, this industrial waste plant material might be further used as a source of the flavonoids.

Keywords: garden sage, glutinos sage, Salvia officinalis L., Salvia glutinosa L., flavonoids, ultrasonic extraction, maceration.

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J. Serb. Chem. Soc. 72 (1) 81–87 (2007)

UDC 633.791:66.061:54–139:546.264–31; JSCS–3537; doi: 10.2298/JSC0701081Z; Original scientific paper

Supercritical fluid extraction of hops

ZORAN ZEKOVIC, IVANA PFAF-SOVLJANSKI and OLGICA GRUJIC

Faculty of Technology, Department of Biotechnology and Pharmaceutical Engineering, University of Novi Sad, Bul. Cara Lazara 1, 21000 Novi Sad, Serbia

(Received 16 January, revised 10 May 2006)

Five cultivars of hop were extracted by the method of supercritical fluid extraction using carbon dioxide (SFE–CO₂) as extractant. The extraction (50 g of hop sAMple using a CO₂ flow rate of 97.725 L/h) was done in the two steps: 1. extraction at 150 bar and 40°C for 2.5 h (sAMple of series A was obtained) and, after that, the sAMe sAMple of hop was extracted in the second step: 2. extraction at 300 bar and 40 °C for 2.5 h (sAMple of series B was obtained). The Magnum cultivar was chosen for the investigation of the extraction kinetics. For the qualitative and quantitative analysis of the obtained hop extracts, the GC-MS method was used. Two of four themost common compounds of hop aroma (a-humulene and b-caryophyllene) were detected in sAMples of series A. In addition, isomerized a-acids and a high content of b-acids were detected. The a-acids content in the sAMples of series B was the highest in the extract of the Magnum cultivar (it is a bitter variety of hop). The low contents of a-acids in all the other hop sAMples resulted in extracts with low a-acids content, i.e., that contents were under the prescribed a-acids content.

Keywords: Humulus lupulus, Cannabinaceae, hop extraction, supercritical carbon dioxide.

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February 05, 2007.
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