JSCS Vol 68, No. 4-5
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J.Serb.Chem.Soc.
68(4–5)239–242(2003) |
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Professor Miroslav J. Gašić
On the occasion of his 70th birthday
This
issue of the Journal of the Serbian Chemical Society is dedicated to Professor
Miroslav J. Gašić and to his main scientific activities in the field of organic
chemistry, on the occasion of his 70th birthday. Professor Gašić certainly made
very important contributions to the development of organic chemistry,
particularly at the University of Belgrade. Therefore, it is my privilege and
great pleasure, as his colleague and close friend for many years, to give a
short professional summary of Professor Gašić on the occasion of his life jubilee.
Professor Miroslav J. Gašić was born on December 30, 1932, in
Belgrade to his father Dr. Jovan and mother Ljubica (nee Djordjević). He
received his secondary school and university education in Belgrade, graduating
from the Faculty of Science, University of Belgrade (B. Sc. in Chemistry) in
1959. In 1964 he obtained a Ph.D. in Chemistry from the same faculty. After
graduation, he became permanent member of the staff at the Faculty of Science,
University of Belgrade, starting as a research assistant (instructor) in 1960,
and then gradually passing through all the teaching positions (Assistant
Professor in 1970, Associate Professor in 1976), to full Professor in Organic
Chemistry (1983). He was teaching Organic Chemistry, Organic Reaction
Mechanisms, Natural Product Chemistry and Industrial Organic Chemistry to
chemistry students at the Department of Chemistry, as well as Organic Chemistry
to molecular biology students at the Department of Biology. At the Faculty of
Science, University of Belgrade, where he spent almost 40 years until his
retirement, becoming Professor Emeritus in 1998, Professor Gašić held the Chair
(Division) of Organic Chemistry for a long time (1985–1996) and was Dean of the
Department of Chemistry and Physical Chemistry in the period of 1982 to 1984.
Since 1981, Professor Gašić has been project coordinator and
research leader in the Center of Chemistry of the Institute of Chemistry,
Technology and Metallurgy in Belgrade, and since 1998 its scientific advisor.
Besides, he was research associate of the Montenegrin Institute of Biological
Investigations in Kotor. He coordinated (or still coordinates) six complex
projects financed by the Republican Ministry of Science (1981–1985, 1986–1990,
1991–1995, 1996–2000, 2001–2003, and 2001–2004), and two projects financed by
the Federal Ministry of Science (1993, and 1995–1997). He was also coordinator
of a series of projects in the area of marine chemistry and biochemistry
(1981–91), as part of a Yugoslav-German cooperation in research and technology,
as well as co-leader of the project on Mediterranean ecology, financed by FAO.
Professor Gašić was a postdoctoral fellow of the Worcester
Foundation for Experimental Biology in the USA (1965–66), research associate at
the University of California, Los Angeles, USA (1966–67), visiting scientist at
Indiana University, Bloomington, USA (1972–73), and visiting scholar at the
National Academy of Sciences, Washington, D.C., in 1983 and 1990.
For his contributions to science, Professor Gašić was elected to the
Serbian Academy of Sciences and Arts in 1985 as a corresponding member, and in
1994 as a full member. For his scientific achievements, Professor M. Gašić also
received the Annual Award of the City of Belgrade (1987) and the Serbian
Chemical Society Award for outstanding contributions to chemistry (1998).
For a long time Professor Gašić has been a very active member of
the Serbian Chemical Society, acting as its general secretary (1970–1972), and
later as president, in the period of 1998–2001. He has been a long time member
of the Editorial Board of the Journal of the Serbian Chemical Society.
Moreover, he was a member of the Executive Committee of the Union of Yugoslav
Chemical Societies and its president in the period 1993–1997, a member of the
American Chemical Society and the German Chemical Society (GDCh), as well as a
member of the Organic Chemistry Commission of the International Union of Pure
and Applied Chemistry.
Professor Gašić’s main scientific interest is in the field of
organic chemistry, more specifically organic reactions and natural product
chemistry, and recently, in the field of biochemistry as well. His research
activity covered a wide range of areas and topics. Chronologically, it began
with the partial synthesis and transformations of steroids resulting in the
preparation of a new structural type of steroids containing a ten-membered
ring. The positions and stereochemistry of functional groups within this
modified steroidal framework provided very stable and suitable models for the study
of the reactivity of and stereoelectronic effects in medium-sized rings, a
topic which at the time was difficult to approach.
After a few years of involvement in reaction mechanisms, he
revived his interest in steroids by using 5,10-seco-steroids containing a
ten-membered ring for the study of the nature of carbocationic intermediates in
solvolysis reactions.
A series of papers by Professor Gašić represented local pioneer
contributions to the application of spectroscopic 1H and 13C-NMR methods in
structural elucidation of organic compounds (stereochemical relationship
between functional groups in a-substituted polycyclic d-lactones, effects
of substituents on the chemical shift of sp2 hybridized carbon atom
signals, structure of alkaloids isolated from local plants, structure
elucidation and quantification of kerogen in oil shales, etc.).
In more recent years, he turned his attention thoroughly to
natural products from marine organisms, their isolation, structure elucidation,
reactivity and biological activity evaluation. In this respect his interest was
primarily focused on compounds with antitumor activity based on redox processes
and on those showing specific interactions with tumor tissues. In this respect,
the investigation of the biological activity of the sesquiterpene avarol,
isolated from the sponge Dysidea avara, should be particularly mentioned. This
compound and a few of its derivatives were found to have marked cytostatic and
antibacterial activity.
Most of Professor Gašić’s work with his colleagues and coworkers
was published in more than a hundred papers in international journals and a few
monographs and patents, or presented at scientific meetings in Europe and the
USA, mostly as plenary, section or visiting professor lectures. In addition to
the Science Citation Index, his papers were cited in various monographs, annual
reviews and monograph series, such as Steroid Reaction Mechanisms (Elsevier),
Reagents for Organic Syntheses (John Wiley & Sons), Alicyclic Chemistry,
Terpenoids and Steroids, and Annual Reports on the Progress of Chemistry (The
Chemical Society, London), Marine Natural Products and Synthesis (Academic
Press), International Review of Science (Butterworths), Modern Synthetic
Reactions (Benjamin), Synthetic Reagents (Elis Horwood Ltd.), Bioorganic
Chemistry (Springer Verlag).
In conclusion, through his diverse activities, teaching and
scientific work, Professor Gašić became one of the leading figures of the
Belgrade University school of Organic Chemistry, thus significantly contributing
to its traditionally high and internationally recognized level.
Dragomir Vitorović
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J.Serb.Chem.Soc.
68(4–5)243–248(2003) |
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Chemical modification of b-lactoglobulin by quinones
IRENA NOVAKOVIC, ZORAN VUJCIC*, TATJANA BOZIC*, NATASA BOZIC*,
NENAD MILOSAVIC* and DUSAN SLADIC*
Institute of Chemistry,
Technology and Metallurgy, Department of Chemistry, Njegoseva 12, P. O. Box
473, 11001 Belgrade and
Faculty of Chemistry, University of Belgrade, Studentski trg
12–16, P. O. Box 158, 11001 Belgrade, Serbia and Montenegro
(Received 31 December 2002)
The avarone/avarol quinone/hydroquinone couple, as well as their
derivatives show considerable antitumor activity. In this work, covalent
modifications of b-lactoglobulin, isolated from cow milk, by avarone, its model
compound 2-tert-butyl-1,4-benzoquinone, and several of their alkylthio
derivatives were studied. The techniques applied for assaying the modifications
were: UV/VIS spectrophotometry, SDS PAGE and isoelectrofocusing. The results of
the SDS PAGE suggest that polymerisation of the protein occurs. The shift of
the pI of the protein upon modification toward lower values indicates that
lysine amino groups are the principal site of the reaction of b-lactoglobulin
with the quinones.
Keywords:
avarone, quinone, b-lactoglobulin, covalent modification.
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J.Serb.Chem.Soc.
68(4–5)249–256(2003) |
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Composition of the lipophilic
extract from the sponge Suberites domuncula
SALVATORE DE ROSA, CARMINE IODICE, JORDAN NECHEV*, KAMEN STEFANOV*
and SIMEON POPOV*
Istituto di Chimica
Biomolecolare C.N.R., Via Campi Flegrei, 34; 80078 Pozzuoli (Naples), Italy and
*Institute of Organic Chemistry with Centre of Phytochemistry,
Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
(Received 26 November 2002)
The composition of the lipophylic extract from the sponge
Suberites domuncula was investigated. Lipids and their fatty acids, as well as
volatile compounds and sterols were identified. Stanols are the main class of
steroids in the investigated sponge. A high concentration of unsaturated long
chain fatty acids (C26–C28) was identified. The presence of branched and odd fatty acids
indicates associated bacteria in the sponge.
Keywords:
lipids, sterols, volatiles, GC/MS, sponge.
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J.Serb.Chem.Soc.
68(4–5)257–268(2003) |
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The hypothetical ancestral
animal. the Urmetazoa: telomerase activity in sponges (Porifera)
WERNER E. G. MÜLLER and ISABEL M. MÜLLER
Institut für Physiologische
Chemie, Abteilung Angewandte Molekularbiologie, Universität,Duesbergweg 6,
D-55099 Mainz, Germany
(Received 29 November 2002)
Sponges (Porifera) represent the lowest metazoan phylum,
characterized by a pronounced plasticity in the determination of cell lineages,
and they are the closest related taxon to the hypothetical ancestral animal,
the Urmetazoa, from which the metazoan lineages diverged. In a first approach
to elucidate the molecular mechanisms controlling the switch from the cell
lineage with a putative indefinite growth capacity to senescent, somatic cells,
the activity of the telomerase as an indicator for immortality has been
determined. The studies were performed with the marine demosponges Suberites
domuncula and Geodia cydonium, in vivo with tissue but also in
vitro using the primmorph system. Primmorphs are formed from dissociated
cells which have retained their proliferation potency. It was found that the
activity of telomerase in tissue of both sponges is high. Based on this and
additional findings it is assumed that the separation of the senescent sponge
cell lineage from the immortal germ-/somatic cell lineage is triggered by the
loss of contact to cell adhesion factors. First evidence is included which
suggests that the final progress of the senescent, telomerase-negative cells to
cell death is caused by apoptosis.
Keywords:
Suberites domuncula, Geodia cydonium, primmorphs, senescence, telomeres,
telomerase, cell lineages, Urmetazoa.
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J.Serb.Chem.Soc.
68(4–5)269–275(2003) |
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A comparative study on the
sterol composition of some brown algae from the Black Sea
ZORNITSA GANCHEVA KAMENARSKA, STEFKA DIMITROVA
DIMITROVA-KONAKLIEVA, KAMEN LJUBOMIROV STEFANOV and SIMEON SIMEONOV POPOV
Institute of Organic Chemistry
with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia 1113,
Bulgaria; E-mail: simpopov@orgchm.bas.bg
(Received 20 July 2002)
The sterol composition of the brown algae Stilophora rhizodes (Turner)
J. Agardh, Punctaria latifolia Grev. and Punctaria plantaginea (Roth.)
Grev. from the Black Sea was investigated. Fifteen sterols were identified in
the sterol fractions. The main ones were cholesterol and
24-methylenecholesterol. Characteristic for brown algae, fucosterol was present
in low concentrations. The results obtained were compared with recent data for
the sterol composition of other Black Sea brown algae. Some conclusions
concerning the evolutionary position of brown algae are made.
Keywords:
Algae, Stilophora rhizodes, Punctaria latifolia, Punctaria plantaginea,
sterols, chemoevolution.
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J.Serb.Chem.Soc.
68(4–5)277–280(2003) |
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Lignans from the plant species
Achillea lingulata
SNEZANA TRIFUNOVIC, VLATKA VAJS*, VELE TESEVIC, DEJAN DJOKOVIC and
SLOBODAN MILOSAVLJEVIC
Faculty of Chemistry,
University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia and
Montenegro and
*Institute for Chemistry, Technology and Metallurgy, Njegoseva 12,
11000 Belgrade, Serbia and Montenegro
(Received 17 December 2002)
Five lignans with a 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane
skeleton, epieudesmin, kobusin, pinoresinol, fargesin and sesartemin, were
isolated from the aerial parts and roots of Achillea lingulata. Their
structures were identified by comparison of their 1H-NMR
and MS data to those in the literature. Fargesin and pinoresinol have not been
isolated previously from any species of the genus Achillea.
Keywords:
Asteraceae, Achillea lingulata, lignans, epieudesmin, kobusin, pinoresinol,
fargesin, sesartemin.
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J.Serb.Chem.Soc.
68 (4–5)281–289(2003) |
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Conformational analysis of
three germacranolides by the PM3 semi-empirical method
SLOBODAN MILOSAVLJEVIC*, IVAN JURANIC*, IVANA ALJANCIC*,**,
VLATKA VAJS*,** and NINA TODOROVIC**
*Faculty of Chemistry,
University of Belgrade, P. O. Box 158, 11001 Belgrade and
**Institute of Chemistry, Technology and Metallurgy, Njegoseva 12,
11000 Belgrade, Serbia and Montenegro
(Received 17 December 2002)
The conformations of the C-6 lactonized germacranolides 1–3
were calculated by applying the PM3 semi-empirical method. The low-temperature 1H-NMR
spectra of parthenolide (1) were also measured. The relations between
the calculated and the experimentally determined geometries were established
using a modified Karplus equation. The applied quantum-chemical calculations
proved to be an efficient and easy-to-use tool for the elucidation and
prediction of the properties of germacranolide-type sesquiterpene lactones.
Keywords:
germacranolides, parthenolide, ridentin,
1b,10a-epoxy-3b,9b-diacetoxy-11a,13-dihydrocostunolide, conformations, PM3
semi-empirical calculations.
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J.Serb.Chem.Soc
68(4–5)291–302(2003) |
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Antimalarial, antimycobacterial
and antiproliferative activity of phenyl substituted mixed tetraoxanes
DEJAN OPSENICA, DENNIS E. KYLE*, WILBUR K. MILHOUS* and BOGDAN A.
SOLAJA**
Institute of Chemistry,
Technology and Metallurgy, Belgrade, Serbia and Montenegro,
*Division of Experimental Therapeutics, Walter Reed Army Institute
of Research, Washington, DC 20307-5100 and
**Faculty of Chemistry, University of Belgrade, P. O. Box 158,
11001 Belgrade, Serbia and Montenegro (E-mail: bsolaja@chem.bg.ac.yu)
(Received 10 November 2002)
Mixed tetraoxanes of the 4”-phenyl-substituted
cyclohexyl-spirotetraoxacyclohexyl-spirocholate series have been prepared and
evaluated as possible antimalarials, antiproliferatives and antimycobacterials.
The activity of the (4”R or S)-phenyl series against P.
falciparum D6 and W2 strains was found to be at the level of artemisinin,
with two compounds, the acid 4 and the amide 6, exhibiting
encouraging anti-TB activity as well. Very promising in vitro results of
the said tetraoxanes were obtained against solid tumours and, in some
instances, the activity against a selected number of cell lines was higher than
that of the antitumor drug paclitaxel.
Keywords:
mixed tetraoxane, malaria, tuberculosis, cancer, peroxide, steroid.
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J.Serb.Chem.Soc.
68(4–5)303–312(2003) |
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Acid-catalyzed and photolytic
reactivity of some unsaturated B-nor-5,10-secosteroidal ketones
MIRA S. BJELAKOVIC* , VLADIMIR D. PAVLOVIC*,**, MILAN
M. DABOVI* and LJUBINKA B. LORENC*,**
*Center for Chemistry, ICTM, P.
O. Box 473, 11001 Belgrade,
**Faculty of Chemistry, University of Belgrade, Studentski trg 16,
P. O. Box 158, 11001 Belgrade, Serbia and Montenegro
(Received 13 December 2002)
The acid-catalyzed reaction of (Z)- and
(E)-B-nor-5,10-seco-ketones 2 and 3 resulted in an intramolecular
cyclization to give the 5-hydroxy-A-nor-1b,5b-10(19)-methylidene derivative 8,
the 5b-hydroxy-A-nor-1(10)-unsaturated compound 9 and the
5b,10a-dihydroxy-A-nor-product 10, from the (Z)-isomer and the
5-hydroxy-A-nor-1a,5b-10(19)-methylidene product 11, from the
(E)-isomer. Upon UV-irradiation, the (Z)- and (E)-seco-ketones 2 and 3
underwent a reversible (Z)/(E) and (E)/(Z)-isomerization and in addition to a
transannular photocyclization to afford the 10(19)-methylidene derivatives 8
and 11, respectively, while photolysis of the
10(19)-methylidene-B-nor-5,10-seco-ketone 4 gave the oxetane derivative 12.
Keywords:
(Z)- and (E)-B-nor-5,10-secosteroidal ketones,
10(19)-methylidene-B-nor-5,10-secosteroidal ketone, acid-catalyzed reactions,
photolytic reactions, mechanistic interpretation.
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J.Serb.Chem.Soc.
68(4–5)313–320(2003) |
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Synthesis of tetrahydrokhusitone. Annulation of
the cyclohexane ring by free radical and carbanionic sequence of reactions
GORAN PETROVIC and ZIVORAD CEKOVIC
Faculty of Chemistry,
University of Belgrade, Studentski trg 16, P. O. Box 158 and
Center for Chemistry, Institute for Chemistry, Technology and
Metallurgy, Njegoseva 12, 11000 Belgrade, Serbia and Montenegro
(Received 16 December
2002)
The synthesis of
norcadinane sesquiterpene tetrahydrokhusitone 1 has been achieved by a
new method for annulation of cyclohexane ring involving a sequence of free
radical d-alkylation of the non-activated carbon atom and intramolecular
carbanionic alkylation. (–)-Menthol was used as the starting compound.
Keywords:
khusitone, norcadinanes, annulation of the cyclohexane ring, 1,5-hydrogen
transfer, cycloalkylation, isomerization, tetrahydrokhusitone.
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J.Serb.Chem.Soc.
68(4–5)321–326(2003) |
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Implicit-OR tiling of
deoxyribozymes: Construction of molecular scale OR, NAND, and four-input logic
gates
MILAN N. STOJANOVIC, DRAGAN B. NIKIC and DARKO STEFANOVIC*
Division of Experimental
Therapeutics and Clinical Pharmacology, Department of Medicine, Columbia
University, Box 84
630W 168th Street, New York, NY 10032, USA and
*Department of Computer Science, University of New Mexico,
Albuquerque, New Mexico 87131, USA
(Received 12 November 2002)
We recently reported the first complete set of molecular-scale
logic gates based on deoxyribozymes. Here we report how we tile these logic
gates and construct new logic elements: OR, NAND, and the first element with
four inputs (i1^i5)Ú(i2^i6). Tiling of logic gates was achieved through a common substrate
used for core deoxyribozyme; degradation of this substrate defines the output.
This kind of connection between logic gates is an implicit-OR tiling, because
it suffices that one componenet of the network is active for the whole network
to give an output of 1.
Keywords:
molecular-scale logic elements, deoxyribozymes, allosteric control.
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J.Serb.Chem.Soc.
68(4–5)327–337(2003) |
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Effects of pH on kinetics of
the structural rearrangement that gates the electron-transfer reaction between
zinc cytochrome c and plastocyanin. Analysis of protonation
states in a diprotein complex
MILAN M. CRNOGORAC AND NENAD M. KOSTIC
Department of Chemistry, Iowa
State University, Ames, Iowa, IA 50011, USA
(Received 13 December 2002)
Electron transfer from zinc cytochrome c to copper(II)plastocyanin
in the electrostatically-stabilized complex [Crnogorac MM, Shen C, Young S,
Hansson O, Kosti} NM (1996) Biochemistry 35, 16465–74]. We study this
rearrangement in four complexes Zncyt/pc(II), which zinc cytochrome c makes
with the wild-type form and the single mutants Asp42Asn, Glu59Gln, and Glu60Gln
of plastocyanin. The rate constant for the rearrangement, kF,
differs for the four forms of plastocyanin but is independent of pH from 5.4 to
9.0 in all four cases. That kF is affected by the single mutations but not by
pH changes suggests that the residues Asp 42, Glu59, and Glu60 in the wild-type
plastocyanin remain deprotonated (i.e., as anions) within the
Zncyt/pc(II) complex throughout the pH range examined. This fact agrees with
the notion that loss of salt bridges in the initial (redox-inactive)
configuration of the complex is compensated by formation of new salt bridges in
the rearranged (redox-active) configuration.
Keywords:
plastocyanin, zinc cytochrome c, pH effects, gated electron transfer,
site-directed mutagenesis, protein-protein rearrangements.
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J.Serb.Chem.
Soc 68(4–5)337–348(2003) |
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Structural studies on
metallobleomycins: The interaction of Pt(II) and Pd(II) with bleomycin
ATHANASIOS PAPAKYRIAKOU, IOANNIS BRATSOS and NIKOS KATSAROS
Institue of Physical Chemistry,
NCSR “Demokritos” 153–10 Ag. Paraskevi Attikis, Athens, Greece
(Received 11 November 2002)
Two of the most successful chemotherapeutic agents used in the
treatment of several neoplasias are bleomycin and cisplatin. Both drugs attack
the DNA leading to the cancer cells death via different mechanisms. In view of
the fact that the combination with each other leads to enhanced activity with
less sever side effects, we have undertaken NMR studies on the complexes formed
between bleomycin and PtII, PdII,
cisplatin and transplatin. Herein we present a brief review of the studies on
metallobleomycins which were carried out by our lab and others, as an outline
of the results obtained using NMR in combination to circular dichroism
spectroscopy. Our data indicate that in most cases and under several conditions
studied, both metal ions form similar complexes with BLM, while more than one
species are present in the solution. Structural implications and comparisons
with other metallobleomycins are being discussed.
Keywords:
bleomycin, platinum, palladium, cisplatin, NMR.
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J.Serb.Chem.Soc.
68(4–5)349–361(2003) |
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Roughness development in
electrodeposited soft magnetic CoNiFe films in the presence of organic
additives
IBRO TABAKOVIC and STEVE RIEMER
Seagate Technology, One Disc
Drive, Bloomington, MN 55435, USA
(Received 10 September 2002)
The effects of three additives, sodium lauryl sulfate (NaLS),
saccharin (Sacc), and NaLS + Sacc, on roughness development during the
electrodeposition of CoNiFe films were investigated. The characterization of
these films by atomic force microscopy shows that the electrodeposits produced
from NaLS containing solution result in a rough surface. The role of NaLS
surfactant is to change the interfacial tension and clean non-polar species
like hydrogen bubbles from the surface. In Sacc containing solution, the evolution
of a smooth surface is controlled by adsorbed Sacc molecule at the interface.
The kinetic roughening of these deposits was investigated by dynamic scaling
analysis. It was demonstrated that the roughness of CoNiFe films, obtained in
the presence of NaLS + Sacc additives, was also dependent on current density,
roughness of substrate, and the temperature of plating bath.
Keywords:
soft magnetic CoNiFe films, morphology, roughness, saccharin, sodium lauryl
sulfate, dynamic scaling analysis.
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J.Serb.Chem.Soc.
68(4–5)363–381(2003) |
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Use of the group theory for
classification of electronic states of acetylene
STANKA JEROSIMIC and MILJENKO PERIC
Faculty of Physical Chemistry,
University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia and
Montenegro
(Received 15 July 2002)
The electronic states of the acetylene molecule are classified
employing the group theory combined with the use of the Walsh diagrams and some
elementary quantum chemical considerations. The results of this analysis are
compared with those obtained by explicit ab initio calculations. It is shown
that the global structure of the electronic spectrum can be
reproduced/predicted without carrying out detailed ab initio calculations.
Keywords:
group theory, Walsh diagrams, classification of electronic states, acetylene.
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J.Serb.Chem.Soc.
68(4–5)383–390(2003) |
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Regiospecificity in the
heterocyclization of b-oxonitriles to 5-substituted 4-oxothiazolidine
derivatives
RADE MARKOVIC*, ZDRAVKO DZAMBASKI**, MILOVAN STOJANOVIC**, PETER
STEEL*** and MARIJA BARANAC*,**
*Faculty of Chemistry,
University of Belgrade, Studentski trg 16, P. O. Box 158, 11001 Belgrade,
Serbia and Montenegro,
**Center for Chemistry ICTM, P. O. Box 815, 11000 Belgrade, Serbia
and Montenegro and
***University of Canterbury, P. O. Box 4800, Christchurch, New
Zealand
(Received 23 December 2002)
A study on the regiospecificity of the base-catalyzed reaction of
activated b-oxonitriles 1 with diethyl mercaptosuccinate affording the title
compounds 3 is reported. Other competitive heterocyclic products, that is
4-oxo-1,3-thiazinanes 4, derivatives of tetrahydrothiophene 5 and/or
thiacyclohexane 6 which on the grounds of mechanistic considerations could be
formed, were not observed. Spectroscopic and experimental evidence, together
with theoretical considerations, provides a reasonable explanation for the
observed regiospecificity.
Keywords:
regiospecific, heterocyclization, 4-oxothiazolidines.
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J.Serb.Chem.Soc.
68(4–5)391–399(2003) |
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Algebraic structure count of
linear phenylenes and their congeners
IVAN GUTMAN
Faculty of Science, University
of Kragujevac, P. O. Box 60, 34000 Kragujevac, Serbia and Montenegro
(Received 27 August 2002)
The algebraic structure count of the linear phenylene with h six-membered
rings is known to be equal to h + 1. We show that the same expression
applies if each four-membered ring in the phenylene is replaced by a linear
array consisting of k four-membered rings, where k = 4, 7, 10,
... For any other value of k, the algebraic structure count is either 0
or 1 or 2, and does not increase with increasing h.
Keywords:
algebraic structure count, Kekulé structures, phenylenes.
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J.Serb.Chem.Soc.
68 (4–5)401–408(2003) |
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Wiener-type indices and
internal molecular energy
IVAN GUTMAN, DUSICA VIDOVIC, BORIS FURTULA and IGOR G. ZENKEVICH*
Faculty of Science, University
of Kragujevac, P. O. Box 60, 34000 Kragujevac, Serbia and Montenegro and
*Chemical Research Institute, St. Petersburg State University,
Universitetsky pr. 26, St. Petersburg 198504, Russia
(Received 7 October 2002)
In earlier studies it was established that internal molecular
energies (Eint) of alkanes can be reproduced, in an approximate yet reliable
manner, by means of a molecular-graph-based structure-descriptor U. It
was also established that U is linearly correlated with the Wiener index
W. We now show that the correlation between U and W is more
complicated than earlier expected, and that it cannot be represented by a
single line. We also show that a very good linear correlation exists between U
and a modified version Wm(l) of the Wiener index, which
is thus more suitable for modeling Eint than
the ordinary Wiener index.
Keywords:
Wiener index, modified Wiener index, internal molecular energy, alkanes.
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J.Serb.Chem.Soc.
68(4–5)409–416(2003) |
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FTIR study of carbon monoxide
adsorption on ion-exchanged X, Y and mordenite type zeolites
V. RAKIC, V. DONDUR*, and R. HERCIGONJA*
Faculty of Agriculture,
Institute of Food Technology, University of Belgrade, Nemanjina 6, 11081
Belgrade - Zemun, P. O. Box 127 and
*Faculty of Physical Chemistry, University of Belgrade, Akademski
trg 12, 11000 Belgrade, P. O. Box 137, Serbia and Montenegro
(Received 7 November 2002)
In this work Fourier transform infrared (FTIR) study has been
applied to study the adsorption of carbon monoxide on transition metal (Mn+, Co2+, Ni2+)
ion-exchanged zeolites type Y, X and mordenites. The adsorption of CO at room
temperature produces overlapping IR absorption bands in the 2120–2200 cm-1
region. The frequency of the band around 2200 cm-1 is
found to be dependent not only on the charge-balancing transition metal cation,
but also on the framework composition. The frequencies of the band near 1600 cm-1 was
found to be dependent on the Si/Al ratio of the investigated zeolites.
Keywords:
FTIR, zeolites, carbon monoxide.
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J.Serb.Chem.Soc.
68(4–5)417–423(2003) |
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A kinetic study of the
depyritization of oil shale HCl-kerogen concentrate by Thiobacillus
ferrooxidans at different temperatures
MIROSLAV M. VRVIC*,** VESNA DRAGUTINOVIC**,***,
VALERIJA MATIC**, SNEZANA SPASIC**, OLGA CVETKOVIC** and DRAGOMIR VITOROVIC*,**
*Faculty of Chemistry,
University of Belgrade, Studentski trg 16, P. O. Box 158, 11001 Belgrade,
**Department of Chemistry, Institute of Chemistry, Technology and
Metallurgy, Njegoseva 12, P. O. Box 473, 11001 Belgrade and
***Institute of Chemistry, School of Medicine, University of
Belgrade, Visegradska 26, 11000 Belgrade, Serbia and Montenegro
(Received 25 December 2002)
The results of kinetic studies of bacterial depyritization of
HCl-kerogen concentrate of Aleksinac (Serbia) oil shale by the
chemolithoautotrophic thionic bacteria Thiobacillus ferrooxidans under
discontinuous laboratory conditions at various temperatures (0, 20, 28 and
37°C) at a pH of ca. 1.5 are presented in this paper. Low pH prevents the
occurrence of the precipitation of iron(III)-ion hydrolysis products on the
substrate particles and thereby reduces the process efficiency. Bacterial
depyritization is developed as per kinetics of the first order. The activation
energy which points to a successive mechanism of pyrite biooxidation, was
computed from the Arrhenius plot. The biochemical kinetics indicators point to
a high affinity of the bacteria toward pyrite but small values of Vmax, which
are probably the result of decelerated metabolic processes due to the low pH
value of the environment resp. the large difference of the pH between the
external medium and the cell interior.
Keywords:
oil shale, Thiobacillus ferrooxidans, depyritization, kinetics.
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J.Serb.Chem.Soc.
68 (4–5)425–433(2003) |
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Transition metal complexes with
thiosemicarbazide-based ligands. Part 45. Synthesis, crystal and molecular
structure of
[2,6-diacetylpyridine bis(S-methylisothiosemicarbazonato)]diazide-iron(III)
VUKADIN M. LEOVAC VLADIMIR DIVJAKOVIC VALERIJA I. CESLJEVIC and
REFIK FAZLIC*
Faculty of Science, University
of Novi Sad, Trg D. Obradovi}a 3, 21000 Novi Sad, Serbia and Montenegro and
*Faculty of Science, University of Tuzla, Univerzitetska 4, 75000
Tuzla, Bosnia and Herzegovina
(Receved 3 January 2003)
The template reaction of a warm methanolic solution of FeCl3.6H2O,
S-methylisothiosemicarbazidehydroiodide and 2,6-diacetylpyridine in the
presence of LiOAc and NaN3 yielded the high-spin complex
[Fe(HL)(N3)2], were HL is the monoanion of the ligand 2,6-diacetylpyridine
bis(S-methylisothiosemicarbazone). X-Ray analysis of the complex showed its
pentagonal-bipyramidal configuration, with pentadenate (N5) HL in
the equatorial plane and two monodentate azide groups in the axial positions.
Crystal data are: monoclinic, P21/c, a
= 1.0263(2), b = 1.2525(2), c = 1.6660(3) nm, b = 98.94°, V =
2.1154 nm3, Z = 4, rx = 1.499 g cm-3, r0 = 1.48
g cm-3, F(000) = 984, m = 9.40 cm-3.
Keywords:
iron(III) complex, 2,6-diacetylpyridine bis(S-methylisothiosemicarbazone)
azide, crystal structure.
Copyright & copy; SHD 2003.
May 15, 2003.
For more information contact: SHD@tmf.bg.ac.yu