JSCS Vol 67, No. 1
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Impresum |
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J.
Serb. Chem. Soc. 67(1) 1–6 (2002) |
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An efficient de novo synthesis of
3’-deoxythymidine from D-xylose
GORDANA CETKOVIC, STEVAN LAJSIC, MIRJANA POPSAVIN*, VELIMIR
POPSAVIN* and DUSAN MILJKOVIC*
Department of Applied Chemistry,
Faculty of Technology, University of Novi Sad, Bulevar Cara Lazara 1 and
*Institute of Chemistry, Faculty of Science, University of Novi
Sad, Trg D. Obradovica 3, YU-21000 Novi Sad, Yugoslavia
(Received
24 April 2001)
An
efficient stereospecific synthesis of 3’-deoxythymidine has been achieved,
starting from D-xylose. The key step of the synthesis involved the NBS promoted
conversion of 5-O-benzoyl-2,3-di-S-ethyl-2,3-dithio-D-ribose
diethyl dithioacetal (4) into the 1-O-acetyl-5-O-benzoyl-2,3-di-S-ethyl-2,3-dithio-b-D-ribofuranose
(5), followed by the stereospecific coupling of the intermediate 5
with silylated thymine, in the presence of ethylaluminium dichloride as the
catalyst.
Keywords:
3'-deoxythymidine, dethioacetalization, N-glycosylation, modified
nucleosides, D-xylose.
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J.
Serb. Chem. Soc. 66(10)7–15(2002) |
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Antioxidant activities of the
constituents of Picris echoides
MIRJANA MILOVANOVIC, KSENIJA PICURIC-JOVANOVIC, VERICA
DJERMANOVIC* and MILUTIN STEFANOVIC**
Department of Food Technology,
Faculty of Agriculture, University of Belgrade, P. O. Box 127, Nemanjina 6,
YU-11081 Zemun,
*Institute of Chemistry, Technology and Metallurgy, Center for
Chemistry, Njegoseva 12, YU-11000 Belgrade and
**Faculty of Chemistry, Studentski trg 16, P. O. Box 158, YU-11001
Belgrade, Yugoslavia
(Received 22 June 2001)
Some flavonoids with antioxidant properties from
the aerial parts of the plant species Picris echoides (family
Asteraceae) were identified. Upon chromatography, the ethyl acetate extract
afforded flavonoids, such as: flavone apigenin (1) and its glucoside,
cosmosiin (2), as well as common plant constituents from this family,
flavonol galetin (3, 3,4’,5,6,7-pentahydroxyflavone) and
4,4’,6,7-tetrahydroxyaurone (4). The structure of the aurone 4 has not
been described so far in the literature and presented a very rare type of
aurone skeleton. The structures of the isolated compounds were determined by
interpretation of their physical and spectral data. The antioxidant activities
of different extracts from Picris echoides were measured by the Schaal
oven test at 60şC and by the Rancimat method at 100şC. Water/ethanol extracts
(2:8, v/v), in concentrations of 0.02 and 0.05 %, showed lower activity than
commercial tocopherol (Tch). On the contrary, the purified ethyl acetate
extracts showed a strong concentration-dependent antioxidant effect. The
investigation demonstrated that galetin was the main flavonol from this origin.
According to the results of the two methods, galetin (3) showed a
two-fold better activity than did Tch and a lower activity than did butylated
hydroxyanisole (BHA). The aurone 4 exhibited significantly lower
antioxidant activity than did galetin at the same concentration level. Thus,
the plant species P. echoides is a new and favorable source of natural lipid
antioxidants.
Keywords:
Picris echoides, Lactuceae, antioxidant activity, flavonoids.
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J.Serb.Chem.Soc.
67(1)17–25(2002) |
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Thiophene based monoazo disperse
dyes for polyester fabric
HARI RAGHAV MARADIYA and VITHAL SOMA PATEL*
V. P. and R. P. T. P. Science
College Vallabh Vidyanagar 388 120, Gujarat State, India and
*Department of Chemistry, Sardar Patel University, Vallabh
Vidyanagar 388 120, Gujarat State, India
(Received 4 May 2001)
A series of monoazo disperse dyes have been
prepared by coupling 2-amino-3-carbethoxy-4,5-dimethylthiophene with various
N-arylmaleimides. The monoazo disperse dyes were characterised by IR spectral
studies and elemental analysis. These dyes were applied at 2 % depth on
polyester fabrics and gave light yellow to brown colour hues with fair fastness
to light and very good to excellent fastness to washing, rubbing, perspiration
and sublimation. The percentage exhaustion of the dyebath and fixation on the
fabric were found to be very good.
Keywords:
2-amino-3-carbethoxy-4,5-dimethylthiophene, disperse dyes, exhaustion,
fixation, polyester, fastness.
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J.Serb.Chem.Soc.
67(1)27–30(2002) |
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N O T E
The
isolation of (6S, 9S)-cyclo(prolylvalyl) from marine
actinomycete, by use of high speed countercurrent chromatography
ANDRIJA SMELCEROVIC, MIRKO SCHIEBEL* and SINISA DJORDJEVIC**
*1Chemical Industry “Nevena”,
Djordja Stamekovica b.b., YU-16000 Leskovac, Yugoslavia,
*Department of Organic Chemistry, Tammanstrasse 2, 37077
Göttingen, Germany and
**Faculty of Technology, Bulevar Oslobodjenja 124, YU-16000
Leskovac, Yugoslavia
(Received
3 May, revised 31 July 2001)
The
marine actinomycete B 1758 came from the actinomycete collection of the Alfred
Wegener Institute for Polar and Marine Research in Bremerhafen, Germany. 1.079
g of raw extract was obtained by fermentation. Seven fractions were separated
by column chromatography on silica gel. Fraction 4 was separated by high speed
countercurrent chromatography. Fraction 4.6 yielded 5.2 mg of (6S, 9S)-cyclo(prolylvalyl).
Keywords:
(6S, 9S)-cyclo(prolylvalyl), marine actinomycete B 1758, HSCCC.
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J.
Serb. Chem. Soc. 67 (1) 31–39(2002) |
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The stability of emulsions in the
presence of additives
S. GASIC, B. JOVANOVIC* and S. JOVANOVIC*
Institute for Plant Protection and
Environment, Teodora Drajzera 9, YU-11000 Belgrade and
*Faculty of Technology and Metallurgy, Karnegijeva 4, YU-11000
Belgrade, Yugoslavia
(Received
26 April, revised 8 August 2001)
The
influence of different additives on the effective HLB values of
non-ionic emulsifiers was studied by the method of the determination of the
phenol index values and by the determination of the emulsion inversion point in
the system with xylene as the oil phase. Ethanol, glycerol and ethylene glycol
were investigated as additives. The method of the determination of the phenol
index value was applied on two homologous series of non-ionic emulsifiers:
nonylphenolpolyglycolethers with 10, 15, 23 and 30 moles of bound ethylene
oxide and polyglycolethers of fatty alcohols (C16–C18) with 15,
20 and 23 moles of bound ethylene oxide. The additives were applied in the
concentration of 5, 10, 15 and 20 %. The results showed that ethanol and
ethylene glycol increased the phenol index value. The influence of ethanol was
more pronounced. On the contrary, glycerol reduces the phenol index value.
There were small differences in the influence of these additives on certain
members of both homologous series, but the general trend is presented here. The
influence of the same additives on the values of the emulsion inversion point
was investigated in the system with xylene and nonylphenolpolyglycolethers with
10 moles of bound ethylene oxide. Ethanol and ethylene glycol were applied in
the concentrations of 1, 5, 10 and 15 %, and glycerol in 5,7.5,10 and 15 %. The
results showed that ethanol and ethylene glycol reduce the emulsion inversion
points, while glycerol increases them. On the basis of these investigations it
can be concluded that ethanol and ethylene glycol could contribute to an
increase in the stability of emulsions, glycerol has the opposite effect. The
results of both applied methods are in accordance.
Keywords:
additives, emulsion, phenol index value, emulsion inversion point.
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J.
Serb. Chem. Soc. 67 (1) 41–51(2002) |
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Extraction and separation studies
of zinc(II) and copper(II) with D2EHPA and PC-88A from perchlorate media
RAJEEV K. SINGH and PURSHOTTAM M. DHADKE
Department of Chemical Technology,
University of Mumbai, Mumbai – 400 019, India
(Received 4 April,
revised 17 July 2001)
The extraction behaviours of Zn(II) and Cu(II)
from perchlorate media have been investigated using bis-2-ethylhexyl phosphoric
acid (D2EHPA) and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester,
(PC-88A) in toluene. The extraction of Zn(II) was found to be quantitative in
the pH range 2.5 to 3.0 and 3.0 to 4.0 using 1.0x10-1 mol dm-3 D2EHPA and 1.0 ´ 10-2 mol dm-3 PC-88A in toluene,
respectively, while Cu(II) was extracted quantitatively in the pH range 6.0 to
8.0 and 5.5 to 7.0 with 1.0x10-2 mol dm-3 and 1.0x10-3 mol dm-3 D2EHPA and PC-88A in toluene,
respectively. Zn(II) was stripped with 4.0 mol dm-3 HCl, while Cu(II) with 2.0 mol dm-3 H2SO4 and 3.0 mol dm-3 HNO3 from the organic phase containing D2EHPA and PC-88A,
respectively. The probable extracted species were ascertained by log D vs.
log [HR] plot to be ZnR42HR and CuR2.2HR for both the reagents. These
methods were used for the determination of Zn(II) and Cu(II) in real samples.
The separation of Zn(II) and Cu(II) were carried out from each other and with
associated metals.
Keywords:
zinc, copper, D2EHPA, PC-88A, extraction, stripping, separation.
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J.Serb.Shem.Soc.
67(1)53–60(2002) |
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The spectroabsorptiometric and
voltammetric behavior of malvin in buffered solutions and its antioxidant
properties
LJUBISA M. IGNJATOVIC, JASMINA M. DIMITRIC MARKOVIC, DRAGAN A.
MARKOVIC and JELISAVETA M. BARANAC
Faculty of Physical Chemistry,
University of Belgrade, Studentski trg 12, P. O. Box 137, YU-11000 Belgrade,
Yugoslavia
(Received
1 March, revised 18 July 2001)
In
the present work the structural transformations of malvin in aqueous acetate
buffer solutions were investigated over a wide pH range under in vitro
conditions using electronic absorption spectroscopy. In addition to the
spectroabsorptiometric investigation, the voltammetric behavior and the
mechanism of the redox process of this molecule were studied, in order to
define its antioxidant properties. The electronic absorption spectra reveal
that the structural changes of malvin, caused by changes in the pH of the
medium, lead to changes in the voltammetric behaviour of this molecule. The
dependence of the oxidation potential of malvin on pH, which can be explained
by the presence of different electroactive molecular structures of malvin at different
pH values, indicates different mechanisms of the electrode process. The
voltammetric activity of malvin is compared semiquantitatively with the
voltammetric activity of a standard synthetic antioxidant, BHA, and a natural
antioxidant, quercetin.
Keywords:
malvin, UV-VIS spectra, cyclic voltammetry, antioxidant properties.
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J.Serb.Chem.Soc.
67(1)61–67(2002) |
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The effect of reversing current
deposition on the apparent density of electrolytic copper powder
K. I. POPOV, LJ. J. POPOVIC*, E. R. IVANOVIC**, V. RADMILOVIC and
M. G. PAVLOVIC**
Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, YU-11000 Belgrade,
*ICTM – Department of Electrochemistry, Njegoseva 12, YU-11000
Belgrade and
**Faculty of Agriculture,University of Belgrade, Nemanjina 6,
11080 Zemun – Belgrade, Yugoslavia
(Received
6 June 2001)
The
possibility of depositing copper powders with different apparent density by
changing the shape of reversing current wave is shown. The morphology and
crystallinity of powder particles can be varied considerably by changing shape
of the reversing current wave and, hence, the apparent density of powders. The
relation of apparent density with particle morphology and structure was
illustrated.
Keywords:
reversing current, apparent density, electrolytic copper powder.
Copyright & copy; SHD 2002.
Last
Updated January 28, 2002.
For
more information contact: SHD@elab.tmf.bg.ac.yu