JSCS Vol 67, No. 3
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Impresum |
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J.Serb.Chem.Soc.
67(3)141–148(2002) |
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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.
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J.Serb.Chem.Soc.
67(3)149–163(2002) |
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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.
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JJ.
Serb. Chem. Soc. 67(3)165–178(2002) |
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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.
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J.Serb.Chem.Soc.
67(3)179-186(2002) |
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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.
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J.Serb.Chem.Soc.
67(3)187–195(2002) |
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Protolytic equilibria of bromazepam
LIDIJA B. PFENDT, GORDANA V. POPOVIC*, TATJANA Z. DAMJANOVIC and
DUSAN M. SLADIC
Faculty of Chemistry, University of
Belgrade, Studentski trg 16, P. O. Box 158, YU-11000 Belgrade and
*Faculty 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 ?C 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.
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J.Serb.Chem.Soc.
67(3)197–211(2002) |
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The effects of grinding on the
physicochemical characteristics of white sepiolite from Golesh
DUSAN VUCELIC, DANA SIMIC*, OLGICA KOVACEVIC*, MIROSLAVA
DOJCINOVIC* and MILAN MITROVIC*
Faculty of Physical Chemistry,
Belgrade University, P.O. Box 550, YU-11001 Belgrade, Yugoslavia
*Institute of General and Physical Chemistry, P.O. Box 551,
YU-11001 Belgrade and
(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.
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J.Serb.Shem.Soc.
67(3)213–220(2002) |
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Application of potentiometric
stripping analysis with constant inverse current in the analytic step for
determining lead in glassware
BILJANA M. KALICANIN, NIKOLA J. MARJANOVIC* and ZVONIMIR J.
SUTUROVIC*
University of Nis, Faculty of
Technology, Bulevar Oslobodjenja 124, YU-16000 Leskovac and
*University 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.
Copyright & copy; SHD 2002.
Last
Updated March 12, 2002.
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more information contact: SHD@elab.tmf.bg.ac.yu