JSCS Vol 65, No. 10
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Impresum 
(39 KB - pdf file); Content of Vol 65, No. 10 (42 KB - pdf file); Instruction for authors (37 KB - pdf file)
J.Serb.Chem.Soc.65(10) 681–689 (2000)
UDC 547.582.4:542.9:541.12.03
JSCS-2792
Original scientific
paper
Synthesis of some bis- and
mono-2-hydroxybenzoic acid derivatives and the determination of their acidity
constants
EVGENIJA A. DJURENDIC , GYÖNGYI GY. VASTAG, TERÉZIA M.
SURÁNYI, MIRJANA M. POPSAVIN and KATARINA M. PENOV GASI
Institute of Chemistry, Faculty of
Sciences, University of Novi Sad, Trg D. Obradovica 3, YU-21000 Novi Sad,
Yugoslavia
(Received 21 March,
revised 14 June 2000)
Several bis- and mono-2-hydroxybenzoic acid
derivatives were synthesized by the reaction of methyl 2-hydroxybenzoate with
some alcohols (diols, polyols and amino alcohols) and their acidity constants
were determined in 60 % aqueous ethanol by the potentiometric titration method.
It has been shown that the biochemical behaviour of these compounds is greatly
dependent on their acidity. It appears that the ester derivatives are weaker
acids than the amide derivatives and, therefore, can be potentially more
involved in the processes of metal ions transport in plants, whereas the
introduction of –OH and –CH3 groups has a very small effect on the
biochemical properties.
Keywords: 2-hydroxybenzoic acid derivatives,
synthesis, acidity constants.
To download this article click here (2351 KB pdf file)
J.Serb.Chem.Soc.65(10)691–694(2000)
UDC 615.28/.281
JSCS–2793
Original scientific paper
An alternative synthesis of
clindamycin
KEITH BOWDEN and GRAHAM P. STEVENS
Department of Biological and
Chemical Sciences, Central Campus, University of Essex, Wivenhoe Park,
Colchester, Essex, UK, CO4 3SQ
(Received 7 June 2000)
A novel synthesis of clindamycin from lincomycin
using N-chlorosuccinimide and triphenylphosphine is reported. This results in
high yields and avoids the use of tetrachloromethane employed in the current
manufacturing process.
Keywords: clindamycin, N-chlorosuccinmide.
To download this article click here (1123 KB pdf file)
J.Serb.Chem.Soc.65(10)695–708(2000)
UDC 547.462.3:539.172.3
JSCS–2794
Original scientific paper
Protonation of maleic and fumaric
acid in aqueous sulfuric acid solutions
KATICA JANKOVSKA, LIDIJA SOPTRAJANOVA* and ILINKA SPIREVSKA*
Faculty of Metallurgy and
Technology, Rudjer Boskovic bb, 91000 Skopje, Macedonia and
*Institute of Chemistry, Faculty of Natural Sciences and
Mathematics, P.O. Box 162, 91001 Skopje, Macedonia
(Received 26 January,
revised 12 June 2000)
The protonations of maleic and fumaric acid in
an acidic medium (aqueous solutions of sulfuric acid) were followed
spectrophotometrically at room temperature. The acid-base equilibria were
characterised qualitatively and quantitatively. The pKBH+ values were determined
using the Hammett equation, employing several acid functions in order to
determine which of them describes best the protonation process of the studied
organic acids. The thermodynamic pKBH+ values as well as those of the solvation
parameters m, m* and f and of the thermodynamic protonation
constants (or, rather, the pKa,p values) were also
defermined. The method of characteristic vector analysis (CVA) was used to
reconstruct the experimental spectra.
Keywords: maleic acid, fumaric acid,
protonation, spectrophotometry.
To download this article click here (4732 KB pdf file)
J.Serb.Chem.Soc.65(10)709–713(2000)
UDC 547.461.3:539.173:541.127
JSCS–2795
Original scientific paper
Belousov-Zhabotinsky oscillatory
reaction. Kinetics of malonic acid decomposition
SLAVICA BLAGOJEVIC, NATASA PEJIC, SLOBODAN ANIC* and LJILJANA
KOLAR-ANIC*
Faculty of Pharmacy, University of
Belgrade, Vojvode Stepe 450, YU-11000 Belgrade and
*Faculty of Physical Chemistry, University of Belgrade, Studentski
trg 12-16, P. O. Box 137, YU-11001 Belgrade, Yugoslavia
(Received 26 April 2000)
The kinetics of the Belousov-Zhabotinsky (BZ)
oscillatory reaction was analyzed. With this aim, the time evolution of a
reaction mixture composed of malonic acid, bromate, sulfuric acid and
cerium(III) was studied at 298 K. Pseudo-first order kinetics with respect to
malonic acid as the species undergoing decomposition with a corresponding rate
constant, k = 7.5×10-3 min-1, was found.
Keywords: kinetics, non-linear dynamics,
oscillatory reaction, Belousov-Zhabotinsky reaction.
To download this article click here (1819 KB pdf file)
J. Serb. Chem. Soc. 65(10)715–723(2000)
UDC 632.952:541.183:549.67:582.28
JSCS-2796
Original scientific paper
Kinetics of aflatoxin B1 and G2 adsorption
on Ca-clinoptilolite
ALEKSANDRA DAKOVIC, MAGDALENA TOMASEVIC-CANOVIC, VERA DONDUR1,
ALEKSANDRA VUJAKOVIC and PREDRAG RADOSEVIC
Institute for Technology of Nuclear
and Other Mineral Raw Materials, P. O. Box 390, YU-11001, Belgrade, and
1Faculty of Physical Chemistry, P. O. Box 137, YU-11001 Belgrade, Yugoslavia
(Received 26 March 2000)
The kinetics of aflatoxins B1 and G2
adsorption on Ca-clinoptilolite at pH 2 and 7, in aqueous electrolyte at 37°C
were studied. For both aflatoxins, the adsorption process begins with a fast
reaction whereby most of the toxin is adsorbed in the first few minutes. This
fast process is followed by the significantly slower process of aflatoxin
bonding at active centers of mineral adsorbent. The initial rate method showed
that the fast adsorption process of aflatoxin B1 and G2,
at both pH values is a first order reaction, while the slow adsorption process
of these aflatoxins is a zero order reaction. The adsorption indexes and
adsorption rates for both examined toxins were pH dependent. In the
investigated initial toxins concentration ranges (500–3000 µg/dm3), high
adsorption indexes were achieved (> 80 %).
Keywords: clinoptilolite, adsorption,
aflatoxin B1, aflatoxin G2.
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J.Serb.Chem.Soc.65(10)725–731(2000)
UDC 543.544.4/.7:547.261/546.212
JSCS–2797
Original scientific paper
Influence of the stationary and
mobile phase composition in ideal chromatographic systems on the log k values
in column chromatography. I. ODS/methanol–water system
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 May 2000)
On the basis of the literature data it was
established that in the case of ODS column chromatography with methanol as
modifier the value log xS/x1 (where xS and x1 denote methanol mole fractions in the
stationary and the mobile phase, respecitvely) is a linear function of the
corresponding Bosch’s PMN parameter as well as of the log k value of the investigated
substances. It was also found that the phase equilibrium in the system
ODS/methanol-water is in accordance with the Everett’s equation for ideal
systems (K = 10.88). Finally, a linear relationship between the log xS/x1 values and the volume fraction of methanol (j)
was found in the range of 0.5–1.0, which corresponds to the linear part of the
function log k = f(j), established experimentally by other authors.
Keywords: C18 liquid chromatography, stationary phase composition, mobile phase
composition, capacity factors, PmN parameter, log k pair linearity rule,
proportionality rule, RPP scale.
To download this article click here (2837 KB pdf file)
J.Serb.Chem.Soc.65(10)733–742(2000)
UDC 543.544.42:661.183.7:547.261:547.722/.728
JSCS–2798
Original scientific paper
Application of the Log k pair
linearity rule and Proportionality rule to the RPP mobile phase scales
estimation on diol-silica column
TOMISLAV J. JANJIC, GORDANA VUCKOVIC and MILENKO B. CELAP
Faculty of Chemistry, University of
Belgrade, P. O. Box 158, YU-11001 Belgrade, Yugoslavia
(Received 12 May 2000)
By the application of the Log k pair
linearity rule and the Proportionality rule to the previously published log k
values for 27 compounds, obtained on diol-silica columns with acetonitrile,
methanol and tetrahydrofuran as modifiers, the existence of common RPP scales
was established. The obtained correlation coefficients of the linear function
log k = f(RPP) were better than 0.9900 for 26 compounds in the first, 21
in the second and 20 in the third case. In addition, in the case of the two
first modifiers a linear correlation between the obtained RPP values and mol %
of modifier in the mobile phase was found. On the basis of this, the following
simple linear function: log k = f(mol % of modifier) was proposed as a
criterion for log k values judgement in practical work. A linear
correlation was also established between intercept and slope of the function,
in spite of the fact that the investigated compounds essentially differ in
their descriptors.
Keywords: column chromatography, diol-silica
sorbent, log k pair linearity rule, proportinality rule, RPP scale.
To download this article click here (4206 KB pdf file)
J.Serb.Chem.Soc.65(10)743–754(2000)
UDC 546.65/654:546.226 33:534.24
JSCS–2799
Original scientific paper
Lanthanide doped alkaline metal
sulphates as candidates for EPR dosimetry
JELENA PETKOVIC, IVANA MLADENOVIC, NIKOLA VUKELIC, MILOS MOJOVIC
and GORAN BACIC
Faculty of Physical Chemistry,
University of Belgrade, Studentski trg 12, YU-11001 Belgrade,Yugoslavia
(Received 2 June 2000)
The applicability of lanthanide doped alkaline metal
sulphates as a new type of dosimeters for EPR dosimetery of ionizing radiation
has been investigated in an attempt to obtain a dosimeter with better
characteristics than the commonly used alanine dosimeter. Irradiation of
samples doped with different lanthanides (Y, Ln, Gd) showed that the best
sensitivity is obtained using dosimeters doped with Y2(SO4)3. Different procedures
for manufacturing dosimeters were studied and an optimum procedure was
established. The time stability of the EPR signal of the irradiated Y2(SO4)3 dosimeter was
investigated using a 15N-PDT standard and no fading of the EPR signal was
observed over at least two weeks. The dose dependence of alanine and Y2(SO4)3 doped K3Na(SO4)13 dosimeters irradiated
in the range 20 Gy – 200 kGy was analysed using a combination of 1-hit and
2-hit mechanisms of free radicals creation.
Keywords: lanthanide doped K3Na(SO4)2,
electron paramagnetic resonance, dosimetry.
To download this article click here (6936 KB pdf file)
J.Serb.Chem.Soc.
65(10)755-761(2000)
UDC 542.4/.47::541.124
JSCS-2800
Original scientific paper
An experimental study of the drying
of granular materials in a packed bed passed by hot air the local humidity of
the material
ANCA MOISE and RADU Z. TUDOSE
Department of Chemical Engineering,
Iasi Technical University, Mangeron nr. 71, Iasi-6600, Romania
(Received 26 July 1999,
revised 14 June 2000)
With the purpose of establishing the mechanism
resposible for the drying of granular materials in a packed bed passed by a
gaseous thermic agent, experimental kinetic study was perormed. In a pilot
plant, the axial and radial distributions of the solid local humidity were
determined in the nonsteady regime. The results show it is possible for three
zones, each at a different state of dryness, to exist in the bed: one zone with
initial humidity, one zone with variable humidity and one zone with dried
material.
Keywords: drying, packed bed, kinetics of
drying.
To download this article click here (298 KB pdf file)
Copyright & copy; SHD 2000.
Last
Updated December 11, 2000.
For
more information contact: SHD@elab.tmf.bg.ac.yu