JSCS Vol 64, No. 2
J. Serb. Chem. Soc.
64(2) 83-89 (1999)
UDC 547.586.2:665.652.4
JSCS-2625
Original scientific paper
Benzylation of N-benzyl-2-phenylacetamide
DUSAN Z. MIJIN, BILJANA M. BOZIC, VIDA D. JANKOVIC, DUSAN G.
ANTONOVIC, NADEZDA D. STOJANOVIC and SLOBODAN D. PETROVIC
Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, P.O.Box 35-08, YU-11001
Belgrade, Yugoslavia
(Received 21 April,
revised 13 November 1998)
N-Benzyl-2-phenylacetamide was used as a model
for the study of the alkylation of N-substituted 2-phenylacetamides with
benzyl chloride in the presence of powdered KOH. The reactions were carried out
in the presence and absence of phase-transfer catalysts, in order to establish
any possible difference in the reaction products. Various phase-transfer
catalysts, solvents and temperatures were used. A comparative study with the
benzylation reaction of other N-substituted-2-phenylacetamides is
presented. The observed lower reactivity of N-benzyl-2-phenylacetamide
in comparison with the reactivity of N-ethyl-2-phenylacetamide and N-phenyl-2-phenylacetamide
can be explained in terms of steric and polar effects.
Key
words: alkylation, N-alkylation, C-alkylation, O-alkylation, N-substituted
2-phenyl-acetamides, phase-transfer catalysis.
J. Serb. Chem. Soc. 64(2) 91-95 (1998)
UDC 547.631.2/.638.1:615.779
JSCS-2626
Original scientific paper
Synthesis and biological activity
of some novel fluorenone-, 2- or 7-nitrofluorenone-1-carbonylamino acid
derivatives
S. A. M. SHEDID and H. M. HASSAN
Chemistry Department, Faculty of
Science, Al-Azhar University, Nasr City, Cairo, Egypt
(Received 15 July 1998)
The synthesis of fluorenone-, 2- or
7-nitrofluorenone-1-carbonylamino acid methyl ester and hydrazide derivatives IV-XXX
is described. Many of the products were found to be active against a number of
microorganisms. The spectral data of the synthesized compounds IV-XXX and the
results of biological screening are briefly discussed.
Key
words: fluorenone-1-carboxylic acids, amino acids, biological activity.
J.
Serb. Chem. Soc. 64(2) 97-108 (1999)
UDC 661.888.1/547.74/.75:691.16
JSCS-2627
Original scientific paper
Vanadyl porphyrins in sedimentary
kerogens/asphaltenes: Estimation of the concentration
PAVLE I. PREMOVIC, THIERRY ALLARD*, NIKOLA D. NIKOLIC, IVANA R.
TONSA and MIRJANA S. PAVLOVIC**
Laboratory for Geochemistry and
Cosmochemistry, Department of Chemistry, Faculty of Science, University of Nis,
P.O.Box 91, YU-18000 Nis, FR Yugoslavia,
*Laboratoire de Mineralogie-Cristallographie, Universit‚s de Paris
VI et VII, Place Jussieu - 75252 Paris Cedex 5, France, and
**Institute of Nuclear Sciences Vinca, P.O.Box 522, YU-11001
Belgrade, FR Yugoslavia
(Received
2 November 1998)
A
new, rapid method for determining the concentration of vanadyl porphyrins (VO2+-P)
associated with the kerogen of bituminous sedimentary rocks, using electron
spin resonance (ESR) is described. The method is simple, straightforward and
inexpensive. Several concentrations of a vanadyl (VO2+) standard
dissolved in glycerol/lignite mixture were prepared. The VO2+
concentrations ranged from 100-1000 ppm. The anisotropic ESR spectra of both
the standards and kerogen samples were recorded at room temperature and the
integrated areas of the pre-selected ESR line (attributed to nuclear spin mI= -5/2)
were computed. The concentrations of VO2+ found in
the kerogen samples were calculated using the relative ratio of the integrated
areas for the standards and the kerogen samples. The VO2+-P
concentrations of the kerogen materials were then calculated using 450 as the
mean molecular weight of these species. The quantitative determination of VO2+-P in the
kerogen fractions in the range 800 ppm and 8000 ppm and higher is feasible by
the method reported. The method of analysis was also extended to asphaltene
samples (enriched with VO2+-P) and a coal sample containing
non-porphyrin VO2+ associated with its organic fraction.
Key
words: vanadyl porphyrins, kerogen, estimation, concentration.
J.
Serb. Chem .Soc. 64(2) 109-116 (1999)
UDC 547.815.1-002.61
JSCS-2628
Original scientific paper
The influence of temperature and
inorganic salts on therheological properties of xanthan aqueous solutions
KATARINA JEREMIC*, SINISA MARKOV**, BRANISLAV PEKIC* and SLOBODAN
JOVANOVIC*
*Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, P.O. Box 35-03, YU-11000
Belgrade and
**Faculty of Technology, University of Novi Sad, YU-21000 Novi
Sad,Yugoslavia
(Received 28 October,
revised 3 December 1998)
The rheological properties of xanthan gum in
aqueous saline solutions and at increased temperatures are of great practical
interest especially for its application in enhanced oil recovery during which
the xanthan solutions are exposed to increased salt contents and relatively
high temperatures. In this work, the influence of high temperature and high
salt concentrations (up to 10 mass%) on the rheological properties of xanthan
was investigated. The influence of three different salts was examined - NaCl,
CaCl2 and FeCl3. Five xanthan samples
were used with the goal of comparing their rheological properties. Four of the
samples were synthesized in the laboratory of one of the authors and one of
them was a commercial sample (BAROID) used for enhanced oil recovery. The
viscosity flow curves were determined for the investigated xanthan solutions
and the obtained results showed that the rheological behavior of the laboratory
prepared xanthan samples was very similar to the rheological behavior of the
commercial sample. The investigated inorganic salts at concentrations as high
as 10 mass% did not influence the viscosity of the xanthan samples, except Fe3+ ion. Temperature had almost no influence on the viscosity in the
investigated interval, especially at the higher shear rates. The shear
dependent activation energies of viscous flow were calculated.
Key
words: xanthan solution, rheologicaal properties, influence of salt content
and temperature.
J.
Serb. Chem .Soc. 64(2) 117-122 (1999)
UDC 546.137/546.41'46''47'''/:541.133
JSCS-2629
NOTE
N O T E
Electric
conductivity of gel-polymeric electrolytes with Ca, Mg and Zn perchlorate salts
NIKOLA CVJETICANIN and SLAVKO MENTUS
Faculty of Physical Chemistry,
University of Belgrade, Studentski trg 12-16, P.O. Box 137, YU-11001 Belgrade,
Yugoslavia
(Received
26 June, revised 11 November 1998)
The
gel-polymeric electrolytes were prepared with calcium, magnesium and zinc
perchlorates dissolved in propylene carbonate together with poly (acrylo
nitrile) or poly(methyl methacrylate) as a solution immobilizing polymers. The
electric conductivity of these electrolytes was examined in the dependence of
temperature and solvent content, at a constant salt-to-polymer concentration
ratio. The electrolyte compositions were outlined having the conductivity close
to 10-3 S cm-1. It was demonstrated that among the factors determining the
conductivity, the cation nature plays a minor role, while the dominant role
plays a liquid solvent (propylene carbonate) concentration.
Key
words: gel-polymeric electrolytes, perchlorates, electric conductivity.
J.
Serb. Chem. Soc. 64(2) 123-130 (1999)
UDC 546.742:541.428.49-541.572.54/
JSCS-2630
Original scientific paper
Thermal investigation of some
chelate Ni(II) complexes
NEVENKA RAJIC, DJORDJE STOJAKOVIC and ROMAN GABROVSEK*
Faculty of Technology and
Metallurgy, University of Belgrade, YU-11000 Belgrade, Yugoslavia and
*National Institute of Chemistry, Ljubljana, Slovenia
(Received
27 October 1998)
Several
diamine-nickel(II) complexes have been prepared and the kinetic parameters of
their decomposition reactions investigated. The complexes undergo a gradual
thermal decomposition. First, water is lost, followed by the departure of the
diamine ligands. The activation energies for the first deamination decrease in
the order Ni(1,2-pd)3Cl2(H2O)2 › Ni(en)3Cl2(H2O)2 >>
Ni(1,3-pd)3Cl2(H2O)2 >> Ni(dieten)2Cl2 (H2O)2 (en =
1,2-diaminoethane; 1,2-pd = 1,2-diaminopropane; 1,3-pd = 1,3-diaminopropane;
dieten = 2-diethylaminoethylamine) which is in accordance with the chelate
effect. The decomposition of the complexes can be represented by a variety of
solid state decomposition models depending on the particular complex, as well
as on the stage of the decomposition.
Key
words: nickel(II) complexes, kinetic parameters, activation energy, thermal
analysis, TG/DTG-DSC.
J.
Serb. Chem. Soc. 64(2) 131-140 (1999)
UDC 661.846/549.6-002.61/
JSCS-2631
Original scientific paper
Physico-chemical characteristics of
sepiolites from Golesh
MARINA RADOJEVIC, MIROSLAVA DOJCINOVIC, DANA SIMIC, VERA VUCELIC
and OLGICA KOVACEVIC
Institute of General and Physical Chemistry,
P.O.Box 551, Studentski trg 12, YU-11000 Belgrade, Yugoslavia
(Received 14 October
1998)
The physico-chemical characteristics of
sepiolite from the Golesh deposit (south Serbia), have been investigated by
means of SEM, XRD, IR spectroscopy, DTA-TG, the BET method and classical
chemical analysis. The textural characteristics of the investigated samples are
related to the content and crystallinity of the sepiolite, as well as to the
content of magnesite, which can reach up to 40%. The thermal characteristics
and IR spectra are typical of sepiolite mineral, accompanied by magnesite.
Key
words: sepiolite, Golesh, SEM, XRD, DTA, TG, BET, IR, chemical analysis.
J. Serb. Chem. Soc. 64(2) 141-147 (1999)
UDC 547.475.2:543.432/547.632.6/
JSCS-2632
Original scientific paper
Kinetic determination of ascorbic acid
in pharmaceuticalsamples
S. S. MITIC, G. Z. MILETIC, S. M. MILETIC and D. A. KOSTIC
Department of Chemistry, Faculty of
Philosophy, University of Nis, YU-18000 Nis, Yugoslavia
(Received
21 October, revised 27 November 1998)
A
kinetic method is described for the determination of ascorbic acid based on its
inhibiting effect on the Mn(II) catalysis of the oxidation of Malachite Green
with potassium periodate. The sensitivity of the method is 35.4 ng cm-3. The
relative error ranges between 2.66 and 7.45% for the concentration interval
35.4 to 354 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. The method was applied for the
determination of ascorbic acid in pharmaceutical samples.
Key
words: kinetic method, ascorbic acid determination, Malachite Green
oxidation, pharmaceutical samples.
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