JSCS Vol 65, No. 8
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J.Serb.Chem.Soc.
65(8) 541-547 (2000)
UDC 547.924/.923:543/.53
JSCS-2774
Original scientific paper
The crystal structure of
14-oxo-13,14-seco-5a-cholest-13(18)-en-3b-yl acetate and the assignment of the
configuration of its acetoxy derivatives
MIRA S. BJELAKOVIC*, VLADIMIR D. PAVLOVIC*,**, LJUBINKA
LORENC*,**, BERNARD TINANT*** and JEAN-PAUL DECLERCQ***
*Center for Chemistry, ICTM, P.O.
Box 815, YU-11001 Belgrade,
**Faculty of Chemistry, University of Belgrade, Studentski trg 16,
P.O. Box 158, YU-11001 Belgrade, Yugoslavia and
***Laboratoire de Chemie Physique et de Cristallographie,
Universite Catholoque de louvain, 1 Place Lous Pasteur, B-1348 Louvain-la
Neuve, Belgium
(Received 15 March 2000)
The crystal structure of 14-oxo-13,
14-seco-5a-cholest-13(18)-en-3b-yl acetate (2), obtained (in addition to
the (E)- D12-isomer 3) by oxidative fragmentation of the
C(13)-C(14) bond of 14a-hydroxy-5a-cholestten-3b-yl acetate (1), was
determined by X-ray analysis. In addition, the configurations of the acetoxy
derivatives 4-6, formed by the thermal lead tetraacetate oxidation of
1, were deduced from the relevant 1H-NMR parameters.
Keywords: X-ray analysis, 14-oxo, 13,
14-seco-5a-cholest-13(18)-en-3b-yl acetate, acetoxy derivatives of, 1H-NMR.
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J.Serb.Chem.Soc.
65(8) 549-553 (2000)
UDC 547.466.25:546.271:543.94
JSCS-2775
Original scientific
paper
Valine-mediated borane reduction of
ketones
A. V. TEODOROVIC, M. D. JOKSOVIC, S. K. KONSTANTINOVIC, J. N.
MILOVANOVIC and B. M. MOJSILOVIC
Faculty of Science, University of
Kragujevac, P.O. Box 60, YU-34000 Kragujevac, Yugoslavia
(Received 24 November
1999)
Acetophenone, 3,3-dimethyl-2-butanone,
3-methyl-2-butanone, and 2-pentanone were reduced with (S)-valine-mediated
borane in very good yields (86-91 %) giving predominantly alcohols of the
(R)-configuration (80, 64, 55 and 36 % ee, respectively).
Keywords: valine-mediated borane, chiral reduction,
acetophenone.
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J.Serb.Chem.Soc. 65(8)555-560(2000)
UDC 547.673:582.29
JSCS-2776
Original scientific
paper
Isolation and antimicrobial acitivity
of anthraquinones from some species of the lichen genus Xanthoria
N. T. MANOJLOVIC, S. SOLUJIC, S. SUKDOLAK and LJ. KRSTIC*
Faculty of Science, University of
Kragujevac, P.O. Box 60, YU-34000 Kragujevac and
*Center for Chemistry, ICTM, P.O. Box 815, YU-11001 Belgrade,
Yugoslavia
(Received 20 December
1999, revised 3 May 2000)
The isolation of six anthraquinones,
erythroglaucin, physcion, xanthorin, emodin, fallacinal and teloschistin, from
three species of the lichen genus Xanthoria (X. fallax, X. elegans and X.
policarpa) is reported. Physcion is the dominant anthraquinone in all species.
the anthraquinones showed broad-spectrum antifingal activity and selective
activity against some phytopathogenic bacterial species.
Keywords: anthraquinones, Xanthoria,
antibacterial activity, antifungal activity.
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J.Serb.Chem.Soc. 65(8) 561-569 (2000)
UDC 546.881:546.027:553.985
JSCS-2777
Original scientific
paper
The vanadium isotopic constitution
of petroleum asphaltenes: La Luna Formation (Venezuela)
PAVLE I. PREMOVIC*, DRAGAN M. DJORDJEVIC*, IVANA R. TONSA*,
LILIANA LOPEZ**, SALVADOR LOMANOCO**, MIRJANA S. PAVLOVIC***, MIOMIR V. VELJKOVIC***
and OLIVERA M. NESKOVIC***
*Laboratory for Geochemistry and
Gosmochemistry, Deparment of Chemistry, Faculty of Science, University of Nis,
P.O. Box 91, YU-18000 Nis,
**Instituto de Ciencias de le Tierra, Facultad de Ciencias, Universidad
Central de Venezuela, Aptdo. 3895, Caracas 1010-A and
***Vinca Institute of Nuclear Sciences, P.O. box 522, YU-11001
Belgrade, Yugoslavia
(Received 10 November
1999)
High resolution mass spectrometry indicates that
the isotopic abundance of 50vanadium (V) of the Late Cretaceous La Luna
petroleum asphaltenes and related source kerogen of marine origin (both highly
enriched with V >> 2000 ppm) is higher by about 3,5 % than that of an
inorganic vanadium source (VOSO4 > 5H2O, Merck). It is proposed that the difference in the 50V/51V values between the La Luna source kerogen/the
associated petroleum asphaltenes and the inorganic source can be best ascribed
to the biological processing of seawater V. The fact that the isotopic
compositions of V vary over a very narrow range (2.46-2.50) suggest an
essentially same (or similar) and fixed bilogical source of V.
Keywords: vanadium, isotope, asphaltene,
petroleum.
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J.Serb.Chem.Soc.
65(8) 571-575 (2000)
UDC 539.126.34:539.12-16
JSCS-2778
Original scientific paper
More hyperenergetic molecular
graphs
JACK H. KOOLEN, VINCENT MOULTON*, IVAN GUTMAN** and DUSICA
VIDOVIC**
FSPM-Strukturbildungsprozesse,
University of Bielefeld, D-33501 Bielefeld, Germany,
*Physics and Mathematics Department (FMI), Mid Sweden University,
sundsvall, S-85170, Sweden and
**Faculty of Science, University of Kragujevac, P.O.Box 60,
YU-34000 Kragujevac, Yugoslavia
(Received 4 November
1999)
If G is a molecular graph and l1, l2, ..., ln are its eigenvalues,
then the energy of G is equal to E(G) = |l1| + |l2| + ... + |ln|. This energy cannot
exceed the value 
. The graph G is said to be hyperenergetic if E(G)
>> 2n - 2. We describe the construction of hyperenergetic graphs G
for which 
.
Keywords: total p-electron energy, energy of
graph, hyperenergetic graphs.
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J.Serb.Chem.Soc. 65(8) 577-580 (2000)
UDC 54.02/.022/.084
JSCS-2779
Note
Note
On
the application of line graphs in quantitative structure-property studies
IVAN GUTMAN and ZELJKO TOMOVIC
Faculty of Science, University of
Kragujevac, P.O. Box 60, YU-34000 Kragujevac, Yugoslavia
(Received 10 December
1999)
Let G be a molecular graph possessing m0(G) edges. let m1(G) be the number
of edges of the line graph L(G) of G, known as the Bertz
index. Let m2(G) be the number of edges of the line
graph of L(G), etc. We examine the applicability of the
sequence mi(G), i = 0, 1, 2, ..., for predicting
physicochemical properties of alkanes. Some earlier obtained results are
extended and amended.
Keywords: line graph, Bertz index, QSPR,
OSAR.
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J.Serb.Chem.Soc. 65(8) 581-585 (2000)
UDC 547.77/.789:543.237.7
JSCS-2780
Note
NOTE
Contribution
to the thermodynamics of 1-(2-thiazolylazo)-2-naphthol in the
water-nitrobenzene extraction system
EMANUEL MAKRLIK and PETR VANURA*
Institute of Physical Engineering,
University of West bohemia, veleslavinova 11, 301 14 Pilsen, Czech Republic and
*Department of analytical Chemistry, Prague Institute of Chemical
Technology, Technicka 5, 166 28 Prague 6, Czech Republic
(Received 12 January,
revised 12 May 2000)
General relations among thermodynamic parameters
characterizing chemical equilibria including species H2A+, HA, H+ and A- in both phases of a two-phase water-nitrobenzene extraction
system have been derived. From the extraction measurements, the equilibrium
distribution constant of electroneutral 1-(2-thiazolylazo)-2-naphthol (TAN, HA)
between the nitrobenzene and aqueous phases has been determined: log KD(HA) = 3.90±0.02. By using this value and further known constants
and applying the mentioned relations, the following values of dissociation constants
of TAN in nitrobenzene saturated with water have been calculated for a
temperature of 25°C: pKdnb(H2A+) = -log Kdnb(H2A+) = 4.9 and pKdnb(HA) = -log Kdnb(HA) = 16.5.
Keywords: 1-(2-thiazolylazo)-2-naphthol,
water -nitrobenzene system, distribution constant, dissociation constants.
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J.Serb.Chem.Soc. 65(8) 587-593 (2000)
UDC 547.473..2:543.257.7:547.565.2
JSCS-2781
Original scientific
paper
Coulometric titrations of bases in
propylene carbonate and g-butyrolactone using hydroquinone as the depolarizer
and a quinhydrone indicator electrode
LJ. N. JAKSIC*, R. M. DZUDOVIC**, R. P. MIHAJLOVIC** and Z. D.
STANIC**
*Faculty of mining and Geology,
University of Belgrade and
**Faculty
of Science, University of Kragujevac, Kragujevac, Yugoslavia
(Received 8 October
1999, revised 11 February 2000)
The application of hydroquinone for the coulometric
generation of hydrogen ions in propylene carbonate (PC) and g-butyrolactone
(GBL) is described. The current-potential curves recorded for theid
sepolarizer, titrated bases, indicator and the solvents used showed that the
investigated depolarizer is oxidized at lower potentials than the oxidation
potentials of other components in the solution. the hydrogen ions generated by
the oxidation of hydroquinone were used for the titration of organic bases
(triethylamine, n-butylamine, pyridine, quinoline, aniline, N,N’-diphenylguanidine,
piperidine, and 2,2’-bipiridine) in PC and GBL with visual (Crystal Violet as
indicator) and potentiometric end-point detection using a quinhydrone electrode
as the indicator electrode. The quinhydrone added to the to be analyzed
solution served both as a source of hydrogen ions and, together with the
immersed platinum electrode, as a quinhydrone electrode. The relative error of
the determination of the bases was about 1 %.
Keywords: propylene carbonate,
g-butyrolactone, coulometric titrations, hydroquinone, base, quinhydrone
electrode.
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J.Serb.Chem.Soc.
65(8) 595-601 (2000)
UDC 546.23:543.062:535.243
JSCS-2782
Original scientific
paper
Kinetic determination of Se(IV) in
pharmaceutical samples
S. S. MITIC, J. I. VUCETICb#, S. M. MILETIC and D. A. KOSTIC
Department of Chemistry, University
of Nis, YU-18000 Nis and
*Faculty of Chemistry, University of Belgrade, YU-11001 Belgrade,
Yugoslavia
(Received 9 December
1999, revised 1 April 2000)
A kinetic method is described for the determination
of Se(IV) based on its inhibiting effect on the Fe(III) catalysis of the
oxidation of C6H5COONa with hydrogen
peroxide. The detection limit is 0.06 µg cm-3. The relative error ranges
between 2.1 and 9.5 % for the concentration interval 0.26 to 2.6 µg cm-3. Kinetic equations are proposed for the investigated process. The
effects of certain foreign ions upon the reaction rate were determined in order
to assess the selectivity of the method. the method was applied for the
determination of Se(IV) in pharmaceutical samples.
Keywords: kinetic method, Se(IV), pharmaceutical
samples.
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J.Serb.Chem.Soc.
65(8) 603-607 (2000)
UDC 615.77.002.2
JSCS-2783
Original scientific
paper
Effects of methyl oleate and tween 80
on the antibiotic productivity and the fatty acid composition of the total
lipids of Streptomyces hygroscopicus CH-7
GORDANA GOJGIC-CVIJOVIC, IVANKA KARADZIC* and JOVAN VUCETIC**
Institute for Chemistry, Technolgy
and Metallurgy, Center for Chemistry, Njegoseva 12, YU-11000 belgrade,
*Institute for Chemistry, Faculty of Medicine, University of
Belgrade, Visegradska 26, YU-11000 Belgrade and
**Faculty of Chemistry, University of Belgrade, Studentski trg 16,
YU-11000 Belgrade, Yugoslavia
(Received 5 November
1999)
The effects of methyl oleate and Tween 80,
hexaene H-85 production stimulators, on the fatty acid composition of the total
lipids of S. hygroscopicus CH-7 were investigated. Besides oleic acid in
the biomass, an increase of the branched chain fatty acid contents was
observed: from 1.6 to 2.1 fold in the medium with methyl oleate and 2.5 - 2.9
in the medium with Tween 80 compared to the base medium. These two additives
act differently on the growth of the producing strain and the uptake of valine,
an essential nutrient. A decreased proteolytic activity and similar cellular
fatty acid profiles indicate that the main effect of the added compounds is to
facilitate the excretion of antibiotics to the outer medium, thus increasing
biosynthesis.
Keywords: Streptomyces hygroscopicus, methyl
oleate, Tween 80, fatty acid(s), polyene antibiotic(s).
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J.Serb.Chem.Soc.
65(8) 609 (2000)
Erratum
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Copyright & copy; SHD 2000.
Last
Updated december 11, 2000.
For
more information contact: SHD@elab.tmf.bg.ac.yu