JSCS Vol 64, No. 3
J. Serb. Chem. Soc. 64(3) 149-154 (1999)
UDC 547.459.6:535.343
JSCS-2633
Original scientific paper
Solvent effects on electronic
absorption spectra of 3-N-(4-substituted phenyl)-5-carboxy uracils
N. V. VALENTIC, G. S. USCUMLIC, M. RADOJKOVIC-VELICKOVIC and M.
MISIC-VUKOVIC
Department of Organic Chemistry,
Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4,
P.O.Box 494, YU-11001 Belgrde, Yugoslavia
(Received
7 December 1998)
Absorption
spectra of some 3-N-(4-substituted phenyl)-5-carboxy uracils
(substiuents: H, Cl, Br, I, Me, Et, OMe, COOH and NO2) were recorded
in twelve solvents in the range 200-400 nm. The effects of solvent polarity and
hydrogen bonding on the absorption spectra are interpreted by means of linear
solvation energy relationships using a general equation of the form n=n0+sp*+bb+aa,
where p* is a measure of the solvent polarity, bis the scale of the solvent
hydrogen bond acceptor basicities and ais the scale of the solvent hydrogen
bond donor acidities.
Key
words: ultraviolet absorption spectra, solvent effects, linear solvation
energy relationships.
J. Serb. Chem Soc. 64(3) 155-162 (1999)
UDC 547.94:582,937:547.741:542.9
JSCS-2634
Original scientific paper
Total synthesis of bisindole
alkaloid Ochrolifuanine A. Study of the Michael type condensation of
ethyl-3-trialkylsiloxy propenoate with tryptamine
INDU P. MALHOTRA and N. MALHOTRA
INTECH, 1957 N. Bronson Avenue #
108, Hollywood, CA 90068, U.S.A.
(Received 17 September
1998, revised 11 January 1999)
The total synthesis of Ochrolifuanine A (1a)
has been completed in seven steps, starting from the condensation of tryptamine
with ethyl-3-trialkylsiloxy propenoate, as the key step. A plausible mechanism
for this reaction is proposed. The structures of the intermediates are also
discussed in light of the spectral data obtained.
Key
words: bisindol alkaloid, Ochrolifuanine A synthesis, Michael type
condesation.
J.
Serb. Chem. Soc. 64(3) 163-168 (1999)
UDC 547.77/.79
JSCS-2635
Original scientific paper
2-(1'-Propylimino)-5-arylidene-4-oxotetrahydro-1,3-thiazoles
KATARINA POPOV-PERGAL, MIROSLAV PERGAL, JÁNOS CSANÁDI* and DEJAN
DJOKOVIC**
Faculty of Forestry, University of
Belgrade, YU-11001 Belgrade,
*Institut of Chemistry, Faculty of Science, University of Novi
Sad, Trg Dositeja Obradovica 3, YU-21000 Novi Sad and
**Faculty of Chemistry, University of Belgrade, Studentski trg
12-16, YU-11000 Belgrade, Yugoslavia
(Received 3 August 1998)
Propylimino derivatives of seven
5-arylidene-2,4-dioxotetrahydro-1,3-thiazoles, through the intermediate
2-thiono-5-arylidene-4-oxotetrahydro-1,3-thiazoles, were synthesized as new
potential biologically active compounds. Log P was calculated for both possible
tautomeric forms. The IR, 1H-NMR and 13C-NMR spectra, as well as M + in the MS are given for
synthesized compounds.
Key
words: heterocycles, synthesis,
5-arylidene-2,4-dioxotetrahydro-1,3-thiazoles, C-2 substitution, 1-propylimino
derivatives.
J.
Serb. Chem. Soc. 64(3) 169-171 (1999)
UDC 547.91/918:542.9:546.814/541.128.1/
JSCS-2636
Preliminary
communication
PRELIMINARY COMMUNICATION
Synthesis of C7-C16-alkyl glycosides in the presence of tin(IV)
chloride as a Lewis acid catalyst
STANIMIR KONSTANTINOVIC, JASMINA PREDOJEVIC, ZORICA PETROVIC,
ALEKSANDRA SPASOJEVIC, BILJANA DIMITRIJEVIC and GRADIMIR MILOSEVIC*
Department of Chemistry, Faculty of
Science, University of Kragujevac, P.O. Box 60, YU-34000 Kragujevac, and
*Merima Chemical Industry, YU-37000 Krusevac, Yugoslavia
(Received 20 November
1998)
The Lewis acid catalyzed glycosylation reaction
of b-peracetylated sugar derivatives (glucose, galactose, xylose, maltose or
lactose) with fatty alkanols is used for the synthesis of C7-C16-alkyl glycosides. The process occurs under the
influence of tin(IV) chloride.
Key
words: synthesis of C7-C16-alkyl
glycosides; tin(IV) chloride as Lewis acid catalyst.
J. Serb. Chem. Soc. 64(3) 173-176 (1999)
UDC 547.572:543.94:661.846.23
JSCS-2637
Short communication
SHORT COMMUNICATION
Reduction
of some rigid ketones in the presence of thermally activated Mg(OH)2 in
2-propanol as hydrogen donor
JOZE FORSEK
Faculty of Chemistry, University of
Belgrade, Studentski trg 12-16, P.O.Box 158, YU-11001 Belgrade, and
Center for Chemistry of the Institute of Chemistry, Technology and
Metallurgy, Njegoseva 12, YU-11000 Belgrade, Yugoslavia
(Received
20 November 1998)
The
cyclic ketones 1 and 4 are reduced with Mg(OH)2 in
2-propanol with a pronounced stereoselectivity to give (practically in
quantitative yield) mixtures of the a - and b-hydroxyl compound in which the
respective equatorial isomer prevails, while a similar reduction of the
steroidal diketones 7 and 10, proceeds both regioselectively
(occuring only at the 3-oxo group) and stereoselectively to produce
preferentially the corresponding 3b-alcohol.
Key
words: thermally activated Mg(OH)2, reduction
of rigid ketones, 2-propanol.
J.
Serb. Chem. Soc. 64(3) 177-189 (1999)
UDC 678.632:541.6:543.51/.544.2
JSCS-2638
Original scientific paper
Study of the structure of
phenol-formaldehyde novolac resins by NMR spectroscopy and gel-permeation
chromatography
SLOBODANKA MARKOVIC, JASNA DJONLAGIC*, JOANNA ZAKRZEWSKA** and
BRANKO DUNJIC*
"PKS"-LATEX - Chemical
Industry, 3 Decembra b.b., YU-32000 Cacak,
*Faculty of Technology and Metallurgy, University of Belgrade,
Karnegijeva 4, YU-11000 Belgrade and
**Institute of General and Physical Chemistry, Studentski trg
12-16, YU-11000 Belgrade, Yugoslavia
(Received 13 July 1998)
13C-NMR spectroscopy and gel-permeation
chromatography studies were carried out on different samples of typical
commercial phenol-formaldehyde novolac resins. Six random novolac resins (NLO
1-6), with decreasing ratios of phenol/formaldehyde from 1:0.75 to 1:0.85, were
prepared in the presence of oxalic acid at two different concentratons. A
high-ortho novolac resin (NL-OO') was synthesized in the pH range 4-6 using
zinc acetate (Zn(OAc)2), as catalyst. An improved description of the
chemical structure, in terms of composition, the number of free para-
and ortho- positions, the isomeric distribution, the degree of
polymerization, the number average molecular weight, the degree of branching
and molecular weight distribution, was obtained.
Key
words: novolac resins, phenol-formaldehyde resins, NMR-spectroscopy,
GPC-chromatography.
J.
Serb. Chem. Soc. 64(3) 191-198 (1999)
UCC 546.732:547.837:541.428.46:615.777
JSCS-2639
Original scientific paper
Biologically active dinuclear
complexes of cobalt(II) with a pendant octaazamacrocyclic ligand and
pseudohalides
GORDANA N. VUCKOVIC, MAJA T. SUMAR, ILIJA D. BRCESKI, VUKADIN M.
LEOVAC* and DRAGANA S. MITIC**
Faculty of Chemistry, University of
Belgrade, P. O. Box 158, YU-11001 Belgrade,
*Institute of Chemistry, Faculty of Science, University of Novi
Sad YU-21000 Novi Sad, and
**Faculty of Biology, University of Belgrade, YU-11000 Belgrade,
Yugoslavia
(Received 27 November
1998)
In the three newly-prepared mixed dinuclear
penta-coordinated cobalt(II) complexes, with the pendant macrocyclic ligand N,N',N'',N'''-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane
(tpmc) and pseudohalides, of the general formula SCo2(NCY)ntpmcC(ClO4)4-n(Y = O, n = 1; Y = S, Se, n = 2), the NCO- group is bridging, and the other two pseudohalides are
nonbridging, i.e., singly coordinated to each metal in the trans
position. It can be supposed that the pendant ligand assumes the boat
conformation, in complex involving the cyanate ligand whereas it is in the
chair conformation in the complexes involving the thiocyanate and selenocyanate
ligands. It was found that these complexes exhibit biological activity towards
the following strains of microorganisms: Esherichia coli (ATCC 25922),
Staphylococcus aureus (ATCC 25923), Bacillus thuringiensis (ssp.
kurstaki), Pseudomonas aeruginosa (ATCC 27853) and Candida albicans.
Key
words: pendant octaazamacrocycle, cobalt(II) complexes, antimicrobial
activity, pseudohalides.
J.
Serb. Chem. Soc. 64(3) 199-205 (1999)
UDC 536.717/.77:539.144.3:541.113
JSCS-2640
Original scientific paper
Hyperenergetic molecular graphs
IVAN GUTMAN
Faculty of Science, University of
Kragujevac, P.O.Box 60, YU-34000 Kragujevac, Yugoslavia
(Received 21 December
1998)
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,. Knowing that E(G)
increases with the number of edges of G, it was expected that the
complete graph Kn has greates energy among all n-vertex
graphs. This, however, is not so and there exist hyperenergetic graphs,
i.e., graphs whose energies exceed E(Kn). It will be shovn how
hyperenergetic graphs can be constructed for all n > 8.
Key
words: total p-electron energy, energy of graph, cluster graph,
hyperenergetic graph.
J.
Serb. Chem. Soc. 64(3) 207-213 (1999)
UDC 549.657.13:541.183.12
JSCS-2641
Original scientific paper
The standard reaction Gibbs energy
of the cation exchange reaction of the biionic (Mg, Na)-form of montmorillonite
ZAGORKA RADOJEVIC, LJILJANA KOSTIC-GVOZDENOVIC* and MARIJA
TECILAZIC-STEVANOVIC*
Lola Institute, Kneza Viseslava
70a, Belgrade, and
*Faculty of Technology and Metallurgy, Karnegijeva 4, YU-11000
Belgrade, Yugoslavia
(Received 24 July,
revised 22 October 1998)
The aim of this paper is to contribute to the
knowledge of the quantitative formulation of the ion exchange reaction in
clays. The equilibrium was studied at 11 °C in a system of solutions of NaCl
and MgCl2, the concentrations of which never exceeded 0.1
mol dm-3, and the "Jelenkovac" montmorillonite,
the particle size of which was below 2 mm. The standard reaction Gibbs energy
of the Mg-Na exchange determined by applying the Gapon equation (DrGoNaMg = 11.9 kJ mol-1) and that obtained according to Levy-Shainberg
(DrGoNaMg = 10.5 kJ mol-1) showed a large degree of concordance. The latter method also
includes the exchangeable ion activity coefficient obtained from ion-clay
interaction data which includes data on the thickness of the interlayer space
in the montmorillonite structure, as well as the thickness of the basis
montmorillonite layer itself.
Key
words: Standard reaction Gibbs energy, cation exchange reaction,
montmorillonite, clays.
J.
Serb. Chem. Soc. 64(3) 215-219 (1999)
UDC 549.742.112:541.183/661.51/.99/
JSCS-2642
Short communication
SHORT COMMUNICATON
SEM-presentation of the sorption of NOx and
ammonia on sepiolite papers
MIROSLAVA DOJCINOVIC, MILAN MITROVIC, MILICA RANCIC and DUSAN VUCELIC
Institute of General and
Physical Chemistry, Studentski trg 12/V, P.O.Box 551, YU-11001 Belgrade,
Yugoslavia
(Received 23 November
1998)
The sorption of NOx and ammonia was performed on
sepiolite paper, laboratory prepared from the mineral sepiolite and cellulose
or glass fibers. It was found that nitric oxides are sorbed at room
temperature; that, in the first adsorption-desorption cycles (desorption at
160°C), a part of the oxides is irreversibly sorbed and the other part is
physically reversibly sorbed, since the adsorbed and desorbed quantities of NOx
are approximately constant during 30 cycles. Ammonia is only physically sorbed
on the sepiolite in the paper, but after saturation of the papers saturation
with NOx, the sorbed quantity increases more than five times. Visualisation of
some of the sorption products on the surface of the sepiolite paper is
presented, in the form of SEM photographs.
Key words: sorption, nitric oxides, ammonia,
sepiolite, SEM.
J.
Serb. Chem. Soc. 64(3) 221-233 (1999)
UDC 539.4/411/.42:621.3.012
JSCS-2643
Original scientific paper
A new procedure for evaluating the material
resistance curve under static loading conditions by applying the potential drop
method
VENCISLAV K. GRABULOV
Military Technical
Institute, Kataniceva 15, YU-11000 Belgrade, Yugoslavia
(Received 9 December
1998)
This paper presents a new technique of J-R curve
evaluation using the continuously cracked single specimen potential drop method
(SSPD). The experiments were performed under static loading conditions on
fatigue precracked standard Charpy specimens. The specimens were machined from
high strength steel, NN-70 (YU version of USA HY-100). The displacement and
potential drop were measured and the evaluated static J-R curve is in good
agreement with the J-R curve obtained by the standard ASTM-E 1152 method. This
method has advantages over the standard procedures, since it uses a single
specimen which is continuously cracked. This opens the perspective to use the
new procedure for evaluating dynamic J-R curves and possibilities for
application on materials with microstructural heterogeneity, i.e.,
welded joints.
Key words: fracture mechanics, J integral, resistance
curve, J-R curve, crack growth, potential drop method, material testing.
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