J.Serb.Chem.Soc. 67(2)69–75(2002)
UDC 66.091.2:547.1-311:661.834
JSCS – 2925
Original scientific paper
Hydride reduction of B-norcholestane 5a,6a-epoxide
MIRA S. BJELAKOVIC,a, VLADIMIR D. PAVLOVIC,a,b# and LJUBINKA B. LORENCa,b#
aCenter for Chemistry, ICTM, P. O. Box 473, YU-11001 Belgrade and bFaculty of Chemistry,
University of Belgrade, Studentski trg 12–16, P. O. Box 158, YU-11001 Belgrade, Yugoslavia
(Received 4 September 2001)
B-Norcholestane epoxide 2 is reduced with lithium aluminium hydride to give either the 3b,6a-diol
3 or the corresponding 3b,5a-diol 4, depending on the quality of the reducing reagent employed.
A plausible mechanistic explanation of the obtained results is suggested.
Keywords: 5a,6a-epoxy-B-norcholestan-3b-yl acetate, 5a-hydroxy-B-norcholestan-3b-yl acetate,
6a-hydroxy-B-nor-5b-cholestan-3b-yl acetate, lithium aluminium hydride, lithium
triethylborohydride.
J.Serb.Chem.Soc. 67 (2)77–85(2002)
UDC
JSCS – 2926
Original scientific paper
The reactivity of a,b-unsaturated carboxylic acids. Part XVI. The kinetics of the reaction of
cycloalkenylcarboxylic and cycloalkenylacetic acids with diazodiphenylmethane in various
alcohols
GORDANA S. USCUMLIC, JASMINA B. NIKOLIC# and VERA V. KRSTIC#
Department of Organic Chemistry, Faculty of Technology and Metallurgy, University of Belgrade,
Karnegijeva 4, YU-11001 Belgrade, Yugoslavia
(Received 15 June, revised 19 September)
The rate constants for the reaction of diazodiphenylmethane with 1-cyclopentenecarboxylic, 1cycloheptenecarboxylic, cyclopent-1-enylacetic and cyclohept-1-enylacetic acids were
determined in eight alcohols at 30 ºC using the appropriate UV-spectroscopic method. In order to
explain the kinetic results through solvent effects, the second order rate constants of the
examined acids were correlated using a total solvatochromic equation, of the form: log k = Ao +
sp* + aa + bb, where p* is a measure of the solvent polarity, b represents the scale of solvent
hydrogen bond acceptor basicities and a represents the scale of solvent hydrogen bond donor
acidities. The correlations of the kinetic data were carried out by means of multiple linear
regression analysis. The opposite sings of the electrophilic and the nucleophilic parameters are in
agreement with the well-known reaction mechanism. The results presented in this paper were
compared with the kinetic data for 1-cyclohexenecarboxylic and cyclohex-1-enylacetic acids
obtained under the same experimental conditions.
Keywords: cycloalkenecarboxylic acids, cycloalkenylacetic acids, diazodiphenyl-methane, kinetic
measurements, protic solvents.
J.Serb.Chem.Soc. 67(2)87–97(2002)
UDC 547.21+541.62:543.632.5
JSCS – 2927
Original scientific paper
Ordering of alkane isomers by means of connectivity indices
IVAN GUTMAN, DUSICA VIDOVIC and ANKA NEDIC
Faculty of Science, University of Kragujevac, P. O. Box 60, YU-34000 Kragujevac, Yugoslavia
(Received 3 September 2001)
The connectivity index of an organic molecule whose molecular graph is G is defined as C(l) =
S(dudu)l, where du is the degree of the vertex u in G, where the summation goes over all pairs of
adjacent vertices of G and where l is a pertinently chosen exponent. The usual value of l is –1/2,
in which case c = C(–1/2) is referred to as the Randic index. The ordering of isomeric alkanes
according to c follows the extent of branching of the carbon-atom skeleton. We now study the
ordering of the constitutional isomers of alkanes with 6 through 10 carbon atoms with respect to
C(l) for various values of the parameter l. This ordering significantly depends on l. The difference
between the orderings with respect to c and with respect to C(l) is measured by a function D and
the l-dependence of D was established.
Keywords: connectivity index, Randic index, alkanes, isomer ordering.
J.Serb.Chem.Soc. 67 (2)99–102(2002)
UDC 543.632.5:547.21+541.62
JSCS – 2928
Original scientific paper
Two theorems on connectivity indices
IVAN GUTMAN
Faculty of Science, University of Kragujevac, P. O. Box 60, YU-34000 Kragujevac, Yugoslavia
(Received 3 September 2001)
Two general cases are pointed out for which the ordering of molecules according to the
connectivity index C(l) is the same for all values of the exponent l.
Keywords: connectivity index, isomer ordering.
J.Seb.Chem.Soc. 67 (2)103–109(2002)
UDC 662.3:547.551.2:541.124
JSCS – 2929
Original scientific paper
A kinetic model for the consumption of stabilizer in single base gun propellants
LJILJANA JELISAVAC and MILOS FILIPOVIC
Military Technical Institute, Kataniceva 15, YU-11000 Belgrade, Yugoslavia
(Received 14 May, revised 16 October 2001)
A suitable kinetic model for the consumption of stabilizer (diphenylamine) in single base gun
propellants was investigated and successfully verified. The model assumes that a reaction of
shifting order can be applied for the consumption of diphenylamine in single base gun
propellants. It was found that the experimental data were well evaluated by a first-order reaction
at high concentrations of diphenylamine in the propellant, but by a zero-order reaction at low
concentrations during the final phase of the propellant life time. The mechanism of diphenylamine
depletion was discussed with relation to the model and the ageing behavior of the propellants.
The kinetic parameters of this model, which permit the calculation of the time up to complete
consumption of the diphenylamine, were determined. The results were compared with the kinetic
data obtained by a widely accepted model, which combines formally reactions of first and zero
order, designated as an “exponential and linear” model. All comparisons gave satisfactory
agreement.
Keywords: single base gun propellants, stabilizer (diphenylamine) consumption, chemical
stability, kinetic model.
J.Serb.Chem.Soc. 67(2)111–113(2002)
UDC 547.551:54.062:539.125.4
JSCS –2930
Note
NOTE
Protonation site for anilines in aqueous media
ALEXEI N. PANKRATOV and INNA M. UCHAEVA
Department of Chemistry, N. G. Chernyshevskii Saratov State University, 83 Astrakhanskaya
Street, Saratov 410026, Russia
(Received 29 August 2001)
By means of the PM3 method it has been shown that the protonation of 2-, 3-, 4-methoxyanilines,
4-methylthioaniline, 2-, 3-, 4-aminobenzoic acids, 2-, 3-, 4-nitroanilines in the gaseous phase
proceeds via the amine nitrogen atom. The same result, attributed to the aqueous medium, was
obtained for 4-methoxyaniline, 4-aminobenzoic acid and 4-nitroaniline.
Keywords: anilines, protonation, quantum chemical computation.
J.Serb.Shem.Soc. 67(2)115–122(2002)
UDC 546.56+546.71:542.913:547.57
JSCS – 2931
Original scientific paper
The synthesis and characterization of nickel(II) and copper(II) complexes with the polydentate
dialkyl dithiocarbamic acid ligand 3-dithiocarboxy-3-aza-5-aminopentanoate
SRECKO R. TRIFUNOVICa , ZORICA MARKOVICb, DUSAN SLADICc#, KATARINA
ANDJELKOVICc#, TIBOR SABOc# and DRAGICA MINICd#
aDepartment of Chemistry, Faculty of Science, University of Kragujevac, P. O. Box 60,
R. Domanovica 12, YU-34000 Kragujevac, bFaculty of Metallurgy and Technology, YU-81000
Podgorica, cFaculty of Chemistry, University of Belgrade, P. O. Box. 158, Studentski trg 16, YU11000 Belgrade and dFaculty of Physical Chemistry, University of Belgrade, P. O. Box 173, YU11001 Belgrade, Yugoslavia
(Received 26 April, revised 3 October 2001)
Square planar complexes of Ni(II) and Cu(II) with potassium 3-dithiocarboxy-3-aza-5aminopentanoate have been prepared by direct synthesis. The obtained neutral complexes were
characterized by elemental analysis, magnetic susceptibility measurements, infrared and
electronic spectra. The thermal behaviour of both the Ni(II) and Cu(II) complexes, and the ligand
itself was investigated by DSC and TG.
Keywords: nickel(II), copper(II), dithiocarbamate, synthesis, complexes, thermal analyses.
J.Serb.Chem.Soc. 67(2)123–126(2002)
UDC 546.73:542.913:66.095.64.094.522
JSCS – 2932
Note
NOTE
Synthesis and characterization of tris[butyl-(1-methyl-3-phenyl-propyl)-dithiocarbamato]cobalt(III) seskvitoluene
GORAN N. KALUDJEROVIC1, VESNA M. DJINOVIC1, SRECKO R. TRIFUNOVIC2#, ISMET M.
HODZIC1# and TIBOR J. SABO1#
1Faculty of Chemistry, University of Belgrade, P. O. Box 158, Studentski trg 16,
YU-11001 Belgrade and 2Department of Chemistry, Faculty of Science, University of Kragujevac,
P. O. Box 60, YU-34000 Kragujevac, Yugoslavia
(Received 24 May, revised 6 September 2001)
A new bidentate ligand butyl-(1-methyl-3-phenyl-propyl)-dithiocarbamate (bmFpdtc) was
prepared, as the sodium salt. In the reaction of hexaaminecobalt(III) chloride with NabmFpdtc, the
corresponding tris[butyl-(1-methyl-3-phenyl-propyl)-dithiocarbamato]cobalt(III), [Co(bmFpdtc)3]
complex was prepared. The complex was characterized by elemental analysis, infrared,
electronic absorption, 1H and 13C-NMR spectroscopy.
Keywords: cobal(III) complex, dithiocarbamate, bidentate ligand.
J.Serb.Chem.Soc. 67(2)127–134(2002)
UDC 66.11–033.6+666.29:666.1.038
JSCS – 2933
Original scientific paper
Glass-ceramic enamels derived from the Li2O-Na2O-Al2O3-TiO2-SiO2 system
DRAGICA S. GAVRILOVSKI1, NIKOLA S. BLAGOJEVIC2, MILORAD P. GAVRILOVSKI1 and
SNEZANA R. GRUJIC2#
1SARTID – Institute for Metallurgy, Goranska 12, YU–11300 Smederevo and 2Faculty of
Technology and Metallurgy, University of Belgrade, Karnegijeva 4, YU–11001 Belgrade,
Yugoslavia
(Received 24 May, revised 18 October 2001)
The results of research on the conditions for obtaining model glass-ceramic enamels, derived
from the basic Li2O-Na2O-Al2O3-TiO2-SiO2 system, by varying the initial composition and
thermal treatment conditions, are presented in this paper. Segregation of the crystal phases in the
glassy-matrix was carried out during subsequent thermal treatment. The formation of different
crystal phases was evidenced through the results of differential-thermal analysis and X-ray
powder diffraction analysis.
Keywords: glass-ceramic enamels, thermal treatment, silicate coatings, crystallization.
J.Serb.Chem.Soc. 67(2)135–142(2002)
UDC 666.11–033.6+666.29:519.87:539.4
JSCS – 2934
Original scientific paper
Modelling glass-ceramic enamel properties
DRAGICA S. GAVRILOVSKI1, NIKOLA S. BLAGOJEVIC2 and MILORAD P. GAVRILOVSKI1
1SARTID – Institute for Metallurgy, Goranska 12, YU–11300 Smederevo and 2Faculty of
Technology and Metallurgy, University of Belgrade, Karnegijeva 4, YU–11001 Belgrade,
Yugoslavia
(Received 14 June, revised 19 September 2001)
The results of an investigation of the chemical and thermal characteristics of glass-ceramic
enamels, derived from the Li2O-Na2O-Al2O3-TiO2-SiO2 system, obtained by employing the
methods of mathematical experiment planning, are presented in this paper. Adequate
mathematical models, showing the dependence of the chemical and thermal stability on the
chemical composition of enamel systems, after different thermal treatment procedures, were
obtained. Based on the testing carried out, it was concluded that in the obtained glass-ceramic
enamels the chemical resistance is decreased, but at the same time, the thermal stability is
increased, relative to reference coatings.
Keywords: glass-ceramic enamels, mathematical planning, chemical stability, thermal stability.