J.Serb.Chem.Soc. 67(3)141–148(2002)
UDC 546.47+546.682:66.095.252.094
JSCS – 2935
Original scientific paper
Intramolecular Barbier reaction in water: cyclopentane and
cyclohexane ring closure
ALEKSANDAR IVKOVIC, RADOMIR MATOVIC and RADOMIR N. SAICIC#
Faculty of Chemistry, University of Belgrade, Studentski trg 16, P. O. Box 158, YU-11000
Belgrade and ICTM – Center for Chemistry, Njegoseva 12, YU-11001 Belgrade, Yugoslavia
(Received 3 August 2001)
Zinc or indium promoted intramolecular Barbier reactions of aldehydes containing a suitably
positioned allylic or propargylic halide unit afford unsaturated cyclic alcohols in moderate yields.
Keywords: Barbier reactions, cyclisation, allylation, allenes, zinc, indium.
J.Serb.Chem.Soc. 67(3)149–163(2002)
UDC 543.635.4+66.088:612.112
JSCS–2936
Original scientific paper
Investigations of the lysophospholipid composition of human
neutrophils under different stimulation conditions by matrix-assisted laser desorption/ionization
time-of-flight mass spectrometry
MARIJANA PETKOVIC, JÜRGEN SCHILLER, MATTHIAS MÜLLER, KLAUS ARNOLD and
JÜRGEN ARNHOLD
Institute of Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Leipzig,
Germany
(Received 8 June 2001)
Matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS) is
usually used for the analyses of proteins, carbohydrates and oligonucleotides. In spite of the
number of advantages that MALDI-TOF MS exhibits for lipid analysis, this method has not often
been applied in this field. In this paper we have extended our previous studies on the suitability of
MALDI-TOF MS for the investigation of changes in the content of lipid-derived second
messengers in organic extracts of human neutrophils. Qualitative differences in the
lysophospholipid composition in organic extracts of the human neutrophils under different
stimulation conditions could be easily observed by MALDI-TOF MS. Although there are still some
methodological problems to be solved before this method can be routinely applied for the
quantification of different lipid classes in complex biological mixtures (such as organic extracts of
human neutrophils) it is shown here that MALDI-TOF MS possesses the capability to be used as
a simple screening method for the investigation of the content of lipid-derived second
messengers and of signalling pathways in cells.
Keywords: lysophospholipids, MALDI-TOF MS, neutrophils, phospholipase, phospholipids, signal
transduction.
J. Serb. Chem. Soc. 67(3)165–178(2002)
UDC 543.544.3:535.64:667.653
JSCS – 2937
Original scientific paper
Inverse gas chromatography of chromia. Part II. Finite surface coverage
A. E. ONJIA*, S. K. MILONJIC*# and LJ. V. RAJAKOVIC**#
*The Vinca Institute of Nuclear Sciences, P. O. Box 522, YU-11001 Belgrade and **Faculty of
Technology and Metallurgy, P. O. Box 494, YU-11001 Belgrade, Yugoslavia
(Received 5 July 2001)
The interactions of n-hexane, benzene, chloroform, and tetrahydrofuran with dried (amorphous)
chromia (I) and chromia heated at 1073 K (crystalline) (II), both obtained from a colloidal
dispersion, and a commercially available chromia (III) were studied by inverse gas
chromatography (IGC) under finite surface coverage conditions. The isotherms, in the
temperature range 383 – 423 K, were used to estimate the surface area, the adsorption energy
distribution, the isosteric heat of adsorption, and the spreading pressure on the surfaces of the
solids. The uniformly reduced adsorption ability of the heated chromia was attributed to the
dehydroxylation of the surface at the higher temperatures. Both solids showed an increased
affinity toward chloroform molecules, as a result of strong acid-base interaction.
Keywords: inverse gas chromatography, chromia, adsorption, organics, isotherms, isosteric heat.
J.Serb.Chem.Soc. 67(3)179-186(2002)
UDC 543.544:517.956:515.518.4
JSCS-2938
Original scientific paper
Theoretical consideration and application of the SP and SP’ scales in RP chromatographic
systems in which Everett’s
equation is valid
T. J. JANJIC#, G. VUCKOVIC and M. B. CELAP#
Faculty of Chemistry, University of Belgrade, P. O. Box 158, YU-11001 Belgrade, Yugoslavia
(Received 18 September 2001)
It is shown that in the case of ODS and less polar modifiers the log k values are a linear function
of the SP’ parameters. This findings differ from earlier investigated systems, in which a linear
dependence between log k and SP parameters (SP = log SP’) was found. Both linear
relationships have been analyzed and the corresponding possible separation mechanisms have
been considered. In addition, the advantages of normalization of both scales are shown and how
then they can be applied in the investigation of substances congenerity.
Keywords: RP column chromatography, Everett’s equation, solvent strength scales, SP
parameter, SP’ parameter, capacity factor.
J.Serb.Chem.Soc. 67(3)187–195(2002)
UDC 547.223:541.123:541.132.3
JSCS - 2939
Original scientific paper
Protolytic equilibria of bromazepam
LIDIJA B. PFENDT1, GORDANA V. POPOVIC2, TATJANA Z. DAMJANOVIC1 and
DUSAN M. SLADIC1#
1Faculty of Chemistry, University of Belgrade, Studentski trg 16, P. O. Box 158, YU-11000
Belgrade and 2Faculty of Pharmacy, University of Belgrade, P. O. Box 146, YU-11000 Belgrade,
Yugoslavia
(Received 1 August, revised 30 October 2001)
The protolytic equilibria of bromazepam, an ampholyte sparingly soluble in water, in
homogeneous and heterogeneous systems were studied in the pH range 0–14 at 25 ºC and at
ionic strength of 0.1 mol/dm3 (NaCl). On the basis of 13C-NMR spectra, the protonation site was
predicted – in acidic media the pyridine nitrogen of bormazepam is protonated. The acidity
constants of bromazepam were determined spectrophotometrically (pKa1 2.83 and pKa2 11.60)
and potentiometrically (pKa1 2.99). In the heterogeneous system the following equilibrium
constants were determined: Ks0 = [HA] (pKs0 3.44), Ks1 = [H2A+]/[H3O+] (pKs1 0.61), and Ks2
= [A-][H3O+] (pKs2 15.04).
Keywords: bromazepam, 1,4-benzodiazepines, acidity constants, heterogeneous equilibria.
J.Serb.Chem.Soc. 67(3)197–211(2002)
UDC 553.67:666.29.022.2:681.542
JSCS – 2940
Original scientific paper
The effects of grinding on the physicochemical characteristics of white sepiolite from Golesh
DUSAN VUCELIC
+, DANA SIMIC*, OLGICA KOVACEVIC*, MIROSLAVA
DOJCINOVIC* and MILAN MITROVIC*
*Institute of General and Physical Chemistry, P.O. Box 551, YU-11001 Belgrade and +Faculty of
Physical Chemistry, Belgrade University, P.O. Box 550, YU-11001 Belgrade, Yugoslavia
(Received 13 July 2001)
The influence of grinding white sepiolites from the Magure-Golesh mine in Southern Serbia on
their structure and on the rheological characteristics of their aqueous suspensions was
investigated. Sepiolite samples of hard and soft consistency were ground in three different types
of mills: a ball mill, air-stream mill, and a colloid mill. The effect of grinding on the sepiolite
samples was investigated by SEM, XRD, IR, TG and BET methods and by chemical analysis.
Grinding generally resulted in the separation of the sepiolite fibers, and partial amorphization. In
addition, grinding produced substantial changes in the apparent viscosity and rheological
characteristics of dilute aqueous suspensions of sepiolite. It is concluded that the viscosities are
especially affected by the type of grinding employed.
Keywords: sepiolite, Golesh, grinding, structure, rheological characteristics.
J.Serb.Shem.Soc. 67(3)213–220(2002)
UDC 543.554+543.641:661.1+546.815
JSCS-2941
Original scientific paper
Application of potentiometric stripping analysis with constant inverse current in the analytic step
for determining lead in
glassware
BILJANA M. KALICANIN1, NIKOLA J. MARJANOVIC2# and ZVONIMIR J. SUTUROVIC2#
1University of Nis, Faculty of Technology, Bulevar Oslobodjenja 124, YU-16000 Leskovac and
2University of Novi Sad, Faculty of Technology, Bulevar Cara Lazara 1, YU-21000 Novi Sad,
Yugoslavia
(Received 7 June, revised 5 November 2001)
The trace amounts of lead in extraction glassware products were determined by potentiometric
stripping analysis with constant inverse current in the analytic step (PSA-iR), an electrochemical
technique of high sensitivity and selectivity. This paper deals with an investigation which was
directed to the effect of a great number of factors on the results of PSA-iR, of lead in glassware,
such as the mercury time electrodeposition, the electrolysis potential, the solution stirring rate and
the constant inverse current. Linearity of the lead analytical signal was achieved within the range
of mass concentrations from 2.5 mg/dm3 to 4.5 mg/dm3. A detection limit of 0.64 mg/dm3 was
obtained, with a reproducibility of 4.14 % expressed as the coefficient of variation. The analyses
were carried out using a computerized stripping analyzer of domestic design and manufacture
(Faculty of Technology, Novi Sad and “Elektrouniverzal”, Leskovac). The accuracy of the method
was confirmed by parallel analyses using flameless atomic absorption spectrophotometry as the
reference method.
Keywords: potentiometric stripping analysis, constant inverse current, lead, glassware.