JSCS Vol 67, No. 6
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Impresum |
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J.Serb.Chem.Soc.
67(6)373-379(2002) |
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Alkylation of N-substituted
2-phenylacetamides: Benzylation of N-(4-nitrophenyl)-2-phenylacetamide
VIDA D. JANKOVIC, DUSAN Z. MIJIN and SLOBODAN D. PETROVIC*
Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, P. O. Box 3503, YU-11001
Belgrade and
*Hemofarm Group, Beogradski put bb, YU-26300, Vrsac, Yugoslavia
(Received
16 January 2002)
N-(4-Nitrophenyl)-2-phenylacetamide was alkylated with benzyl
chloride in the presence of powdered potassium hydroxide at different
temperatures and in various solvents in order to establish the reactivity and
orientation in the reaction. The reactions were also carried out in the
presence of different phase-transfer catalysts in toluene. Product formation
was followed by GC. The obtained results were compared to the results of the
benzylation of other N-substituted 2-phenylacetamides, especially of N-phenyl-2-phenylacetamide.
Keywords:
alkylation, benzylation, 2-phenylacetamides, phase-transfer catalysis.
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J.Serb.Chem.Soc.
67(6)381-392(2002) |
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Reductive deactivation of some s-triazine
herbicides: prometryne, desmetryne and terbutryne
RAFAELMARÍN GALVÍN, JOSÉ MIGUEL RODRÍGUEZ MELLADO and MARÍA JOSÉ
HIGUERA
Departamento de Química Física y
Termodinámica Aplicada, Facultad de Ciencias, Campus Universitario de
Rabanales-Edificio C-3. Universidad de Córdoba, E-14071-Córdoba, Spain
(Received
10 January, revised 4 March 2002)
The
electrochemical behaviour (DC and DPpolarography) of the
methylthio-bis(alkylamino) s-triazine herbicides prometryne, desmetryne and
terbutryne on mercury electrodes has been studied in the acidity range 2.25 M H2SO4 to pH 6.5.
Two two-electron irreversible reduction processes were found, complicated with
adsorption. At pH values higher than the protonation pKof the triazine ring (ca.
4), this protonation reaction preceded the reduction processes. Reduction
mechanisms are proposed for pH < pKand pH > pK. The products obtained in
the electroreduction of dilute solutions of the above herbicides show a lower
toxicological effect than that of the original compounds (lower aromatic
character and cleavage of the –SCH3 group). Thus,
electrochemical deactivation at pH 3.5
and at potentials around –1.10 V (vs. the Ag/AgCl/KClsat electrode)
can be a valid method to deactivate these molecules. Finally, the reductive
route can be an alternative environmental degradative process in waters under
strong reductive conditions, with pH values equal or lower than 3.5 pH-units,
and rich in carbonaceous materials on clays. In these ambients oxidative
photolytic detoxification of herbicides cannot occur.
Keywords:
DC and DP polarography, prometryne, desmetryne, terbutryne, triazine
herbicides.
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J.Serb.Chem.Soc.
67(6)393-406(2002) |
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Indene dimerization products
JOVAN JOVANOVIC, MICHAELSPITELLER* and WILHELM ELLING*
Faculty of Technology and
Metallurgy, University of Belgrade, P. O. Box 3503, YU-11120 Belgrade,
Yugoslavia, E-mail: jajovan@drenik.net and
*Institute for Environmental Research, University of Dortmund,
Otto-Hahn–str. 6, D-44221 Dortmund, Germany, E-mail:
spiteller@infu.uni-dortmund.de
(Received
18 February 2002)
The
reaction of 1H-indene (indene) in the presence of Friedel-Crafts acids
was studied. As expected [M. Spiteller, J. Jovanovic, Fuel 78 (1999)
1263] there were dimers and trimers in the product mixture together with higher
oligomers. Among products with double molecular weight relative to the
molecular weight of indene, the structure of four compounds was determined:
6-(2’,3’-dihydro-1’H-inden-1’-yl)-1H-indene, 2-(2’,3’-dihydro-1’H-inden-1’-yl)-1H-indene,
1-(2’,3’-dihydro-1’H-inden-2’-yl)-1H-indene and
2,3,1’,3’-tetrahydro-[1,2’]biindenylidene. It was shown that the first one
represents an indene alkylation product and that the others were obtained by
bonding of the indan-1-ylium ion and indene at the position 2, followed by acid
catalyzed 1,2-hydride rearrangement in the case of the third and fourth one.
Considering the indene dimerization products as components of pyrolysis oils
and as interesting compounds to be used as model substances for NMR, MS and
X-ray analysis, the reaction, separation and isolation parameters were
optimized in this study.
Keywords:
dimers of indene; structure elucidation; NMR spectroscopy; MS spectrometry;
HPLC chromatography.
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J.Serb.Chem.Soc.
67(6)407–413(2002) |
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Chemical applications of the
Laplacian spectrum. VI. On the largest Laplacian eigenvalue of alkanes
IVAN GUTMAN, DUSICA VIDOVIC and DRAGAN STEVANOVIC*
Faculty of Science, University of
Kragujevac, P.O. Box 60, YU-34000 Kragujevac, and
*Department ofMathematics, Faculty of Science, University of Nis,
Yugoslavia
(Received
28 February 2002)
The
largest Lapacian eigenvalue m1 of the molecular graph is a quantity important in the theory of
the photoelectron spectra of saturated hydrocarbons. It is shown that in the
case of alkanes, the presence or absence of quaternary carbon atoms is the main
structural feature on which m1 depends. Within sets of all alkanes with a given number of carbon
atoms the species (with and without quaternary carbons atoms) whose m1-values are
minimal and maximal are determined.
Keywords:
Laplacian spectrum, molecular graph, alkanes.
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J.Serb.Chem.Soc.
67(6)415–423(2002) |
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Far-infrared spectroscopy of PbTe
doped with iron
P. M. NIKOLIC, K. RADULOVIC, D. VASILJEVIC-RADOVIC, V.
BLAGOJEVIC*, B. MILOSAVLJEVIC** and Z. DOHCEVIC-MITROVIC***
Institute of Technical Science of
SASA, P. O. Box 315, YU-11000 Belgrade,
*Faculty of Electrical Engineering, Belgrade University, P. O. Box
35-54, YU-11120 Belgrade,
**Institute of Copper, Department for Chemical and Technical
Control, Bor and
***Institute of Physics, P. O. Box 75, YU-11000 Belgrade,
Yugoslavia
(Received
26 February 2002)
Far
infrared reflection spectra, at room and liquid nitrogen temperature, of PbTe
single crystals doped with iron are presented. Plasma minima were observed at
about 160 cm–1 and 180 cm–1 for room and liquid nitrogen
temperature, respectively. Using the reflectivity diagrams and their minima,
the values of the hole concentrations and their mobility at both temperatures
were calculated and compared with galvanomagnetic measurements. All these
results indicated that when PbTe is doped with a small concentration of Fe, the
hole concentration is reduced by one order of magnitude and the free carrier
mobility is larger when compared to pure PbTe.
Keywords:
lead telluride, doped, infrared spectroscopy, plasma.
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J.Serb.Chem.Soc.
67(6)425-436(2002) |
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Comparison of the influence of
nitrate ions on the electrochemical behaviour of iron and carbon steels in
sulphate solutions
HOUYI MA*, SHENHAO CHEN*,**, CHAO YANG*** and JINGLI
LUO***
*Department of Chemistry, Shandong
University, Jinan, 250100, P. R. China,
**State Key Laboratory for Corrosion and Protection of Metal,
Shenyang, 110015, P. R. China and
***Department of Chemical and Materials Engineering, University of
Alberta, Edmonton, Alberta, Canada, T6G 2G6
(Received
21 January 2002)
The
effect of nitrate ions on the electrochemical behaviour of iron (ferrite) and
two carbon steels (martensite and pearlite) in sulphate solutions of different
pH values was investigated by cyclic voltammetry, polarization and
electrochemical impedance spectroscopy. The pitting inhibiting effect of
nitrate ions on ferrite in sulphate media is pH dependent. Nitrate ions were
unable to inhibit the pitting on ferrite in neutral sulphate solutions, but did
effectively protect passivated ferrite from pitting in acidic sulphate
solutions. No pitting occurred on the surface of the martensite and pearlite
specimens in sulphate solutions, regardless of the pH of the solutions. At the
open-circuit corrosion potentials, the three materials underwent general
corrosion. The impedance spectra for the three materials measured in neutral
sulphate solutions containing nitrates and chlorides at the corrosion
potentials all showed a capacitive loop, while in acidic sulphate solutions
their impedance spectra were greatly reduced in size and displayed at least a
low frequency impedance loop (inductive or capacitive loop) besides the
well-known high frequency capacitive loop. The variation of the impedance
behaviour with pH is explained.
Keywords:
pitting, general corrosion, passive film, cyclic voltammogram, polarization
curves.
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J.Serb.Chem.Soc.
67 (6)437–443(2002) |
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Reflection and structural
characteristics of semi-bright and mirror bright nickel coatings
NEBOJSA D. NIKOLIC, ZLATKO RAKOCEVIC*, DEJAN R. DJUROVIC* and
KONSTANTIN I. POPOV**
ICTM – Institute of
Electrochemistry, Njegoseva 12, P. O. Box 473, YU-11001 Belgrade,
*Vinca Institute of Nuclear Sciences, P. O. Box 522, YU-11001
Belgrade and
**Faculty of Technology and Metallurgy, Karnegijeva 4, P. O. Box
3503, YU-11001 Belgrade, Yugoslavia
(Received
28 January, revised 11 February 2002)
The
reflection and structural characteristics of the nickel coatings obtained in
the presence of a basic brightening addition agent only, and of both a basic
and top brightening addition agent are examined. It is shown that the nickel
coating obtained in the presence of both a basic and top brightening addition
agent fulfilled the conditions to be characterized as a mirror bright metal
surface. The nickel coating obtained in the presence of a basic brightening
addition agent only is characterized as a semi-bright metal surface.
Keywords:
bright nickel coatings, STM technique, X-ray diffraction analysis.
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J.Serb.Chem.Soc.
67 (6)445–455(2002) |
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The influence of electroless plated
chromium on printing properties of aluminum offset printing plate
P. M. ZIVKOVIC, S. JOVANOVIC, N.M. ILIC* and K. I. POPOV
Faculty of Technology and Metallurgy,
Karnegijeva 4, P. O. Box 35-03, YU-11001, Belgrade and
*Vinca Institute of Nuclear Sciences, P. O. Box 522, YU-11001,
Belgrade, Yugoslavia
(Received
21 January, revised 25 February 2002)
A
method for the improvement of the printing properties of offset printing forms
is presented. Specimens of technical aluminum were electrochemically roughened
and treated in different alkaline solutions of chromium chloride in order to
chemically deposit a chromium layer. The composition of the surface layer was
investigated by EDAX. Chromium was found on the specimens that had been treated
in an alkaline solution of chromium chloride, while no chromium was found on
chemically untreated specimens or on specimens that had been treated in an
alkaline solution without chromium chloride. The spectral reflectance from
treated and non-treated specimens was also measured. The chromium-treated
specimens were brighter than the non-chromium-treated ones. The wettability of
the chromium-treated samples was compared with the wettability of the
non-chromium treated samples by measuring the contact angle with water and the
wetted area. The chromium-treated samples showed increased wettability compared
with the non-chromium-treated samples.A printing test was performed under real
printing conditions. Control prints was analyzed densitometrically and
statistically. The chromium-treated printing forms gave clearer prints than the
non-chromium-treated printing forms under all printing conditions.
Keywords:
aluminum, chromium, electroless deposition, printing plates.
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J.Serb.Chem.Soc.
67 (6)457–463(2002) |
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The analysis of the kinetics of
extraction of resinoids and hypericines from the amber, Hypericum perforatum
L.
ANDRIJA A. SMELCEROVIC, SINISA M. DJORDJEVIC*, ZIKA D. LEPOJEVIC**
and DRAGAN T. VELICKOVIC***
Chemical Industry
"Nevena", Djordja Stamenkovica b.b., YU – 16000 Leskovac,
*Faculty of Technology, Bulevar Oslobodjenja 124, YU – 16000
Leskovac,
**Faculty of Technology, Bulevar Cara Lazara 1,YU – 21000 Novi Sad
and
***Pharmaceutical and Chemical Industry "Zdravlje",
Vlajkova 199, YU – 16000 Leskovac, Yugoslavia
(Received
28 September 2001, revised 4 February 2002)
The
kinetics of the extraction of the overall extracted materials (resinoids),
total hypericine, hypericine and pseudohypericine from amber (Hypericum
perforatum L.) was investigated by the procedure of maceration both with
and without ultra-sound, using methanol as the extractant. It was found that
the period of fast extraction with intensification of the extraction of
resinoid by ultra-sound was significantly shorter (about 20 minutes) than was
needed for the extraction without ultra-sound (about 5 h). Similar results were
also obtained for the extraction of the other tested substances. It can be
concluded that better drug exploitation can be achieved in a much shorter
extraction time by intensification of the extraction using ultra-sound. By
preparation of herbal material through pulverization, a significant grade of
herbal tissue structure disintegration was achieved, so that turbulent mass
transfer plays a dominant role in the extraction. The results show that the
coefficient values of fast extraction
(b)
are approximately the same for all the investigated kinetics.
Keywords:
Hypericum perforatum L., kinetics of extraction, resinoids, total
hypericine,hypericine, pseudohypericine.
Copyright & copy; SHD 2002.
Last
Updated July 15, 2002.
For
more information contact: SHD@elab.tmf.bg.ac.yu