JSCS Vol 66, No. 3
Adobe Acrobat version
|
These articles were
created using Adobe Acrobat and were compressed using WinZip |
To download the latest
|
|
|
To download the text
of the whole issue click here |
To download the latest
|
|
Impresum 
(39 KB - WinZip file); Content of Vol 66, No. 3 (26 KB - pdf file); Instruction for authors (37 KB - pdf file)
J.Serb.Chem.Soc. 66 (3)139–152(2001)
547.582.2:547.462.3:542.0
JSCS–2841
Original scientific paper
Synthesis and characterization of
thermoplastic copolyester elastomers modified with fumaric moieties
VESNA ALEKSANDROVIC and JASNA DJONLAGIC
Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, YU-11000 Belgrade,
Yugoslavia
(Received 18 September
2000)
A series of poly(ether-ester)s derived from
dimethyl terephthalate (DMT), dimethyl fumarate (DMF), 1,4-butandiol (BD) and
poly(tetramethylene oxide) (PTMO,Mn = 1000 g/mol) was
synthesized in a two stage process involving transesterification and
polycondensation in the melt. The mole ratio of the starting components was
selected to result in copolymers with a constant hard:soft segment wieght ratio
(56:44). The amount of DMF was 10 mol %, referred to the total amount of the
esters used. The synthesis was optimized in terms of both the concentration of
catalyst, tetra-n-butyl-titanate, Ti(OBu)4 and thermal stabilizer N,N’-diphenyl-p-phenylenediamine,
DPPD, as well as the temperature. The composition and structure of the
synthesized poly(ether-ester)s were characterized by 1H-NMR. The number average molecular weights of the polymers
calculated from the 1H-NMR spectra were compared with the
corresponding values of the inherent viscosity (hinh) in m-cresol and the complex dynamic viscosity (h *). The
effect of the content of fumaric residues on the thermal properties of the
synthesized copolyesters was also investigated using differential scanning
calorimetry (DSC) and thermal gravimetric analysis (TGA).
Keywords: thermoplastic elastomers,
poly(ether-ester)s, fumaric residue, 1H-NMR-spectroscopy.
To download this article click here (122 KB pdf file)
J.Serb.Chem.Soc.
66 (3)153–159(2001)
UDC 548.56:547.476.6
JSCS–2842
Original scientific paper
Characterization of polymer-liquid
crystal blends
DANIELA FILIP, CRISTOFOR I. SIMIONESCU and DOINA MACOCINSCHI
“Petru Poni” Institute of
Macromolecular Chemistry, Aleea Gr. Ghica Voda 41 A, 6600 Jassy, Romania
(Received 14 August,
revised 6 December 2000)
Blends of semi-crystalline polymers
(polyethylene adipate and two poly(ester-urethane) s) with liquid crystal
cholesteryl palmitate with different compositions were prepared by solution
casting. One of the poly(ester-urethane)s was based on 2,4-tolylene
diisocyanate (TDI) and the other one on 4,4’-diphenylmethane diisocyanate
(MDI). The miscibility and phase transition were investigated over the whole
range of concentration by differential scanning calorimetry and polarizing
optical microscopy.
Keywords: liquid crystal, blend, polyester,
poly(ester-urethane).
To download this article click here (89 KB pdf file)
J.Serb.Chem
Soc. 66(3)161–172(2001)
UDC 547.551/.1:541.51
JSCS–2843
Original scientific paper
Gaseous-phase proton affinity of
anilines: A quantum chemical evaluation and discussion in view of aqueous
basicity
ALEXEI N. PANKRATOV, INNA M. UCHAEVA, SERGEI YU. DORONIN and RIMMA
K. CHERNOVA
Department of Chemistry, N. G.
Chernyshevskii Saratov State University, 83 Astrakhanskaya Street, Saratov
410026, Russia
(Received 15 September,
revised 4 December 2000)
Using the PM3 method, enthalpies and free
energies of the gaseous-phase proton affinity (PA) have been computed
for aniline and 62 of its derivatives with different kinds of electron-donor
and electron-acceptor substitution in the aromatic ring and at the nitrogen
atom. Linear correlations of the type pKavs. PA have been found.
Deviations of the data for ortho substituted anilines from the above
relationships was discussed in view of possible hydrophobic hydration of the
molecular fragments ajacent to the protonation centre. Linear dependeces Pexpar = bPtheor (where P is standard entropy, heat or Gibbs
energy of formation, first ionization potential, molecular dipole moment) were
found.
Keywords: anilines, proton affinity,
basicity, quantum chemical computation, theory-experiment correlation,
hydrophobic hydration.
To download this article click here (92 KB pdf file)
J.Serb.Chem.Soc.
66(3)173–178(2001)
UDC 543.54:547.49
JSCS–2844
Original scientific paper
Application of the Log k
pair linearity rule and Proportionality rule to the RPP mobile phase scales
estimation on cyano-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 13 November
2000)
On the basis of literature-reported log k
values, the Log k pair linearity rule and the Proportionality rule were found
to be also valid in the case of cyano-silica sorbent, whenmethanol,
acetonitrile or propane-2-olwere used as modifiers. The RPP scales, reflecting
the solvent strength, are in good linear relationship with the experimentally
determined log k values. Furthermore, in the case of methanol and acetonitrile,
the linear dependence: log k = f (mol% of modifier) was also
established. In the function obtained in a such way, the intercept and the
slope exhibit an approximate linear dependence. Finally, in the case of
methanol, the experimentally obtained log k values are in a satisfactory
agreement with the values calculated by the above equation.
Keywords: column chromatography, cyano-silica
sorbent, Log k pair linearity rule, Proportionality rule, RPP scale.
To download this article click here (68 KB pdf file)
J.Serb.Chem.Soc.
66(3)179–188(2001)
UDC 546.273/546.26:543.257.1
JSCS–2845
Original scientific paper
Potentiometric application of
boron- and phosphorus-doped glassy carbon electrodes
BILJANA F. ABRAMOVIC, VALÉRIA J. GUZSVÁNY, FERENC F. GAÁL and
ZORAN V. LAUSEVIC*
Institute of Chemistry, Faculty of
Science, Trg D. Obradovica 3, YU-21000 Novi Sad and
*Vinca Institute of Nuclear Science, P. O. Box 522, YU-11001
Belgrade, Yugoslavia
(Received 19 September,
revised 5 December 2000)
Acomparative study was carried out of the
potentiometric application of boronand phosphorus-doped and undoped glassy
carbon samples prepared at the same heat treatment temperature (HTT 1000°C).
The electrochemical activities of the obtained electrode materials were
investigated on the example of argentometric titrations. It was found that the
electrochemical behaviour of the doped glassy carbon samples are very similar
to a Sigri (undoped) glassy carbon sample (HTT 2400°C). The experiments showed
that the potentiometric response depends on the polarization mode, the nature
of the sample, the pretreatment of the electrode surface, and the nature of the
supporting electrolyte. The amounts of iodide, bromide, and of chloridewere
determined to be 1.27 mg, 0.80 mg and 0.54 mg, respectively, with a maximum
relative standard deviation of less than 1.1%. The obtained results are in good
agreement with the results of comparative potentiometric titrations using a
silver indicator electrode. The titrationmethod was applied to the indirect
determination of pyridoxine hydrochloride, i.e., vitamin B6.
Keywords: boron- and phosphorus-doped glassy
carbon electrodes; potentiometric titration of halides; determination of
vitamin B6.
To download this article click here (106 KB pdf file)
J.Serb.Chem.Soc.
66(3)189–198(2001)
UDC 648.75
JSCS–2846
Original scientific paper
The application of Near Infrared
Reflectance Spectroscopy (NIRS) for the quantitative analysis of hydrocortisone
in primary materials
K. NIKOLICH, C. SERGIDES and A. PITTAS
Medochemie Ltd, Limassol, Cyprus
(Received 15 May,
revised 5 December 2000)
Near Infrared Reflectance Spectroscopy (NIRS),
coupled with fiber optic probes, has been shown to be a quick and reliable
analytical tool for quality assurance and quality control in the pharmaceutical
industry, both for verifications of raw materials and quantification of the
active ingredients in final products. In this paper, a typical pharmaceutical
product, hydrocortisone sodium succinate, is used as an example for the
application of NIR spectroscopy for quality control. In order to develop an
NIRS method with higher precision and accuracy than the official UV/VIS
spectroscopic method (BP '99), 19 samples, taken from one year’s production and
several prepared in the laboratory, having a hydrocortisone sodium succinate
concentration in the range from 89.05%to 95.83 %, were analysed by NIR and
UV/VIS spectroscopy. Three frequency ranges: 5939.73–5627.32 cm-1; 4863.64 – 4574.36 cm-1; 4308.23–4200.24 cm-1, with the best positive correlation between the changes in the
spectral and concentration data, were chosen. The validity of the developed
NIRS chemometric method for the determination of the hydrocortisone sodium
succinate concentration, constructed by the partial least squares (PLS)
regression technique, is discussed. A correlation coefficient of 0.9758 and a
standard error of cross validation (RMSECV)of 1.06%were found between the UV/VI
Sand ňhe NIR spectroscopic results of the hydrocortisone sodium succinate
concentration in the samples.
Keywords: FTNIRS, quantitative analysis,
hydrocortisone.
To download this article click here (94 KB pdf file)
J.Serb.Chem.Soc.
66(3)199–204(2001)
UDC 632.95
JSCS–2847
Original scientific paper
Development and optimization of a
method for the determination of simazine, atrazine and propazine using
solid-phase extraction and HPLC/GC
VERA TRAJKOVSKA, SIMKA PETROVSKA-JOVANOVIC and MIRKO CVETKOVSKI*
Institute of Chemistry, Faculty of
Science, "St. Cyril and Methodius University", P.O. Box 162, 91000
Skopje, Macedonia and
*Republic Institute of Hydrometeorology, Skupi bb, 91000 Skopje,
Macedonia
(Received 18 May,
revised 25 December 2000)
Asolid-phase extraction (SPE) method, coupled
with HPLC/DAD and GC/FID analysis has been developed for the simultaneous
determination of simazine, atrazine and propazine in water samples. The
compounds of interest were enriched on Envi-carb SPE tubes. The recoveries for
simazine, atrazine and propazine from spiked Nanopure water were 101±5.6 %,
99±4.9 % and 96±5.7 %, respectively. The detection limits were 4.00, 8.00 and
10.00 ng absolute samplemass in the column for simazine, atrazine and
propazine, respectively. Standard curve r2 values of 0.9828–0.9988 for the analyzed compounds were
consistently obtained.
Keywords: determination, solid-phase extraction,
HPLC/GC, atrazine, simazine, propazine.
To download this article click here (75 KB pdf file)
J.Serb.Chem.Soc.
66(3)205–211(2001)
UDC 577.16/612.015.6
JSCS–2848
Original scientific paper
Kinetic determination of rutin
S. S. MITIC, J. I. VUCETIC*, S. M. MILETIC and D. A. KOSTIC
Department of Chemistry, University
of Nis, Cirila i Metodija 2, YU-18000 Nis, and
*Faculty of Chemistry, University of Belgrade, YU-11000 Belgrade,
Yugoslavia
(Received 18 October,
revised 18 December 2000)
Akinetic method is described for the
determination of rutin based on its inhibitory effect on the Fe(II)-AA
catalysis of the oxidation of C6H5COONa with hydrogen peroxide. Detection limit of this method is
0.16 ng cm-3. The relative error ranges between 0.9 to
9.8%for the concentration interval 0.82 ng cm-3 to 8.2 ng cm-3. Kinetic equations are proposed for the
investigated process. The effects of certain foreign ions upon the reaction
rate were determined for the assessment of the selectivity of the method.
Keywords: kinetic method, rutin,
determination.
To download this article click here (84 KB pdf file)
Copyright & copy; SHD 2001.
Last
Updated May 19, 2001.
For
more information contact: SHD@elab.tmf.bg.ac.yu