J. Serb. Chem. Soc. 63(11) 833-840 (1998)
UDC 547.593.4:547.92
JSCS-2590
Original scientific paper
Stereoselective transformation of
cyclodecene-1,4-dione systems, derived from steroids, to the corresponding
spiro-g-lactones
LJUBINKA
LORENC*,**, LIDIJA BONDARENKO-GHEORGHIU**, VLADIMIR PAVLOVIC*,**,
NATALIJA KRSTIC** and MIHAILO LJ. MIHAILOVIC*,**
*Faculty of Chemistry, University of Belgrade,
Studentski trg 12-16, P.O.Box 158, YU-11001 Belgrade and
**Center
for Chemistry, ICTM, P.O.Box 815, YU-11001 Belgrade, Yugoslavia
(Received 4 August 1998)
The thermal and acid-catalyzed intramolecular rearrangement
of the (Z)- and (E)-cyclodecene-1,4-dione compounds derived from
steroids, 2a,b and 3a,b, respectively, proceeds stereoselectively
to give the corresponding configurationally different spiro-g-lactone
derivatives, the (5R,9R)-isomers 4a,b (from the (Z)-cyclodecenediones
2a,b) and the (5R,9S)-isomers 5a,b (from the (E)-cyclodecenediones
3a,b). A possible mechanistic pathway of the observed intramolecular
process leading to the spiro-g-lactone structures is discussed.
Key words: steroidal
cyclodecene-1,4-dione systems, stereoselective transformation, spiro-g-lactones.
J. Serb. Chem. Soc. 63(11) 841-844 (1998)
UDC 547.768:547.587.51
JSCS-2591
Note
N
O T E
The
preparation of an isoxazole derivative of 4-hydroxycoumarin
LjUBOMIR
KRSTIC, SLAVICA SOLUJIC*, SLOBODAN SUKDOLAK*, MILUTIN STEFANOVIC** and DUSAN SLADIC**
*Center for Chemistry, ICTM, Njegoseva 12, POB
815, 11001 Belgrade,
**Faculty
of Science, Department of Chemistry, Radoja Domanovica 12, 34000 Kragujevac and
***Faculty
of Chemistry, University of Belgrade, POB 158, YU-11001 Belgrade, Yugoslavia
(Received 9
July 1998)
A method
for preparation of an isoxazole derivative of 4-hydroxycoumarin,
3-phenyl-5-(4-hydroxy-3-coumarinyl)-isoxazole has been described. The reaction
sequence includes addition of bromine to 3-cinnamoyl-4-hydroxycoumarin, and the
subsequent treatment of the obtained dibromo derivative with 2 equivalents of
sodium azide. Due to steric reasons, the azido group is introduced in the b-position
with respect to the side chain carbonyl group, so that an isoxazole ring can be
formed. The total yield of the reaction was 58%.
Key words: 4-hydroxycoumarin,
isoxazole, azidovinyl ketones.
J. Serb. Chem. Soc. 63(11) 845-850 (1998)
UDC 547.964:546.73-541.428.49
JSCS-2592
Original scientific paper
Investigation of complexes of the tripeptides
Leu-Leu-Tyr and Leu-Ser-Phe with Co(III)
LIDIA
BARBARA JASIŃSKA, JAN RYSZARD RUMIŃSKI*, PIOTR GUGAc and DOROTA KACZYŃSKA**
*Department of Chemistry, The Ludwig Rydygier
Medical University, 85-363 Bydgoszcz, Poland,
**Institute
of Chemistry, N. Copernicus University, 87-100 Toru, Poland and
***Centre
of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363
Lódź, Poland
(Received 17
February, revised 31 August 1998)
Complexes
of Co(III) with Leu-Leu-Tyr (LLY) and Leu-Ser-Phe (LSF) peptides were obtained.
HPLC chromatograms suggest that the peptides are included into the Co(III)
complexes in an intact form. The complex LLY/pentammine Co(III) was isolated by
means of RP-HPLC, and characterized using 1H-NMR and LSMS techniques. The obtained
NMR spectra indicate that the aromatic ring of tyrosine acts as a ligand to the
cobalt cation.
Key words: peptides,
cobalt(III) complexes, HPLC.
J. Serb. Chem. Soc. 63(11)851-862(1998)
UDC 541.124-16:546.76'77''78'''/54-31/
JSCS-2593
Original scientific paper
A thermoanalytical study of the solid state
reactions in Li2CO3 - MexOy systems
N.
COLOVIC, M. ANTONIJEVIC and S. MILIC
Technical Faculty Bor, University of Belgrade,
P.O. Box 50 YU-19210 Bor, Yugoslavia
(Received
13 December 1997, revised 17 June 1998)
The
results of a study of the kinetics of the reaction between lithium carbonate
and the oxides of some transition metals (Cr, Mo, W) are presented in this
work. The reactions were carried out under non-isothermal conditions, in an air
atmosphere. The transformation degree, a, was surveyed by thermogravimetric
analysis. It was established by analysis of the experimental data that the
reaction between lithium carbonate and chromium(III) oxide occurs in one stage,
and that the reactions of molybdenum and wolfram oxides with lithium carbonate
are more complex. The values of the basic kinetic parameters (energy of
activation and pre-exponential factor) for all stages of the examined reaction
were also determined. The energy of activation for the reaction between Li2CO3 and Cr2O3 is 97.3 kJ/mol, for
the reaction between Li2CO3 and MoO3 (I stage) 120.6 kJ/mol, and for the reaction
between Li2CO3 and WO3 (I stage) 167.1
kJ/mol. Based on the values of the energies of activation and the
pre-exponential factors, a compensation effect was observed.
Key words: solid
state reactions, lithium carbonate, chromium, molybdenum and wolfram oxide,
compensation effect.
J. Serb. Chem. Soc. 63(11)863-868(1998)
UDC 546.34'822'':541.65
JSCS-2594
Original scientific paper
The optical properties of non-annealed LiNbO3
ALEKSANDAR
GOLUBOVIC, RADOS GAJIC* and ANDREJA VALCIC**
Institute of Chemistry, Technology and
Metallurgy, Njegoseva 12, YU-11000 Belgrade,
*Institute
of Physics, P.O.Box 57, YU-11001 Belgrade and
**Faculty
of Technology and Metallurgy, Karnegijeva 4, YU-11000 Belgrade, Yugoslavia
(Received
11 March, revised 30 June 1998)
Single
crystals of LiNbO3were grown by the
Czochralski technique. X-ray measurements were performed on the powder to
obtain the lattice parameters. The optical properties of non-annealed samples
LiNbO3 single crystals were
studied to investigate the effect of non-annealing on the optical properties.
Obtained results are discussed and compared with published data.
Key words: Czochralski
technique, LiNbO3, single crystals, optical properties,
non-annealing.
J. Serb. Chem. Soc. 63(11) 869-875 (1998)
UDC 546.776:547.565.3
JSCS-2595
Original scientific paper
Spectrophotometric study of the reaction of
molybdenum(VI) with sodium-pyrogallol-5-sulphonate. The determination of
molybdenum
MIRJANA
V. OBRADOVIC, SNEZANA S. MITIC, DRAGAN S. VESELINOVIC* and
DANIELA C. NASKOVIC**
Department of Chemistry, Faculty of Philosophy,
University of Nis, Cirila i Metodija 2, YU-18000 Nis,
*Faculty
of Physical Chemistry, University of Belgrade, P.O.Box 137, YU-11001 Belgrade
and
**D.D.
Zdravlje, Leskovac, YU-16000 Leskovac, Yugoslavia
(Received
17 April, revised 10 July 1998)
On the
basis of spectrophotometric measurements and applying the Job, Harvey-Manning,
mole ratio and the Franck-Ostwald methods it has been found that, in acid
media, molybdenum(VI) and sodium-pyrogallol-5-sulphonate (PS) form a complex
SMoO3(PS)2C2-. The wide absorption
maxima of this complex is at 314-375 nm. The stability constants of this
complex were calculated by using the Job and the Franck-Ostwald methods. The
thermodynamic values, D H°, DG°, and DS°, of the complex have also been
calculated. A spectrophotometric method for molybdenum determination has been
developed. The method is applied for the determination of molybdenum in steel.
Key words: molybdenum
determination, spectrophotometry, sodium-pyrogallol-5-sulphonate, complex.
J. Serb. Chem. Soc. 63(11) 877-882 (1998)
UDC 541.135:66.087
JSCS-2596
Original scientific paper
Elimination of nucleation exclusion zones by
electrodeposition at a reversing current
N.
D. NIKOLIC, E. R. STOJILKOVIC*, K. I. POPOV** and M. G. PAVLOVIC
ICTM-Institute of Electrochemistry, Njegoseva
12, YU-11000 Belgrade,
*Faculty
of Agriculture, University of Belgrade, Nemanjina 6, YU-11080 Zemun-Belgrade
and
**Faculty
of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, YU-11000
Belgrade, Yugoslavia
(Received
10 July 1998)
Elimination
of nucleation exclusion zones by electrodeposition at a reversing current (RC)
in the seconds time range is considered. It is shown that nucleation exclusion
zones formed in constant regimes can be eliminated by a reversing current only
if the deposition process is under full diffusion control.
Key words: metal
deposition, reversing current, exclusion zones.
J. Serb. Chem. Soc. 63(11) 883-889 (1998)
UDC 582.886:66.066.1:661.97
JSCS-2597
Original scientific paper
Extraction of Oenothera biennis seed oil
with supercritical carbon dioxide - determination of the content of gamma
linolenic acid in seed oil
IRENA
ZIZOVIC, DEJAN SKALA and MIHAJLO RISTIC*
Faculty of Technology and Metallurgy,
Karnegijeva 4, YU-11000 Belgrade and
*Institute
for Medical Herbs "Dr Josif Pancic", Tadeusa Koscuska 1, YU-11000
Belgrade, Yugoslavia
(Received 4
March, revised 8 July 1998)
Oenothera
biennis
oils can be extracted from seeds using usual organic solvents or by applying
the modern method of extraction based on supercritical carbon dioxide as the
solvent. The solubility of oil in supercritical carbon dioxide depends on the
temperature and pressure conditions of the extraction, i.e., on the
density of the carbon dioxide. The fatty acids content of the extracted oils
was analyzed after hydrolysis of the oil and the preparation of their methyl
esters using conventional procedures.
Key words: supercritical
extraction, Oenothera biennis, gamma linolenic acid.
J. Serb. Chem. Soc. 63(11) 891-901 (1998)
UDC 541.183.5:628.3:62.001.57
JSCS-2598
Original scientific paper
Modelling of a fixed bed adsorption column for
waste water treatment
VERA
D. MESHKO, LJILJANA T. MARKOVSKA, MIRJANA B. MINCEVA and VIOLETA V. CIBULIC*
Faculty of Technology and Metallurgy,
University "St. Cyril and Methodius", Ruger Boskovic 16,
91000-Skopje,
Republic
of Macedonia and
*
Public - Health Institute, Leskovac, Yugoslavia
(Received 6
June 1998)
A fixed
bed adsorption column for purification of waste water from textile fibres
colouring has been studied. All investigations were performed under dynamic
conditions at a constant temperature on united collective composite waste water
samples. A natural zeolite was used as the adsorbent. The mathematical model of
the fixed bed adsorption column, used for computer simulation, is based on mass
balance of the column and mass balance of a particle in the column. The
positions and shape of the breakthrough curve profile depend on several
factors, including the physical and chemical properties of both the sorbate and
sorbent, the influent concentration of sorbate, the particular rate limiting
mechanism, the nature of the equilibrium conditions, the height of the column and
the flow rate. The relative effects of these factors are highly specific to a
particular sorbent-sorbate system which constitutes one of the major
difficulties in designing such a process.
Key words: adsorption
column design, purification, waste water, textile dyeing.
Society Home Page Contents of this Vol. Journal Home Page
Copyright & copy; SHD 1996-98 .
Last
Updated November 5, 1998
For more
information contact: SHD@elab.tmf.bg.ac.yu