JSCS
Vol 76, No. 11
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J. Serb. Chem. Soc. 76 (11) 1455–1463 (2011)
UDC
547.587.11:54–145.2+547.262:54–723.4; JSCS–4219; doi: 10.2298/JSC100506129F; Original scientific paper
Deprotonation
of salicylic acid and 5-nitrosalicylic acid in aqueous solutions of ethanol
MOHAMMAD FARAJI, ALI
FARAJTABAR*, FARROKH GHARIB** and HASSAN GHASEMNEJAD-BORSA
Department of Chemistry,
IslAMic Azad University, Babol Branch, Babol, Iran
*Department of Chemistry,
IslAMic Azad University, Jouybar Branch, Jouybar, Iran
**Chemistry Department,
Faculty of Sciences, Shahid Beheshti University, Tehran, Evin, Iran
(Received 6 May, revised 21 June 2011)
The protonation constant values of two hydroxybenzoic acids (salicylic
and 5-nitrosalicylic acid) were studied in some water–ethanol solutions using
spectrophotometric and potentiometric methods
at 25 °C and in an ionic strength of 0.1 M sodium perchlorate. The results
indicated that the pKa values
increase with increasing proportion of ethanol in mixed solvent. The
dependence of the protonation constants on the variation of the solvent were
correlated by the dielectric constants of the media. Furthermore, for a better
understanding of the solvent influence, the obtained results were explained in
terms of the KAMlet–Taft parAMeters a (hydrogen-bond donor
acidity), p* (dipolarity/polarizability) and b (hydrogen-bond acceptor basicity) by means of linear solvation energy
relationships. The multiple linear regression analysis indicated that the pKa values of salicylic acid were strongly
dependent on the non-specific electrostatic solvent–solute interactions,
whereas specific hydrogen bonding interactions controlled the protonation of
nitrosalicylic acid in water–ethanol binary mixtures.
Keywords: pKa;
hydroxybenzoic acids; binary mixtures; solvent effects.
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J. Serb. Chem. Soc. 76 (11) 1465–1470 (2011)
UDC
634.722:581.19:581.48:633.879.6; JSCS–4220; doi: 10.2298/JSC110617132G; Original scientific paper
Chemical composition of white currant seed extract
DEJAN GOĐEVAC, VLATKA VAJS,
SLOBODAN MILOSAVLJEVIĆ*, BOBAN ĐORĐEVIĆ**, GORDANA ZDUNIĆ*** and VELE TEŠEVIĆ
Institute of Chemistry,
Technology and Metallurgy, University of Belgrade, Njegoševa 12, Belgrade,
Serbia
*Faculty of Chemistry,
University of Belgrade, Studentski trg 16, Belgrade, Serbia
**Faculty of Agriculture,
University of Belgrade, Nemanjina 6, Zemun, Serbia
***Institute for Medicinal
Plants Research Dr Josif Pančić, Tadeuša Košćuška 1, Belgrade, Serbia
(Received 17 June 2011)
From the seeds of white currant (Ribes rubrum,
cv. White ChAMpagne), a new sesquiterpenoid glycoside 1 was isolated, along with two known compounds:
dihydrophaseic
acid 3’-O-b-D-glucopyranoside (2), and
3-carboxymethylindole-1-N-b-D-glucopyranoside (3). The structure of
the new compound was identified as dihydrophaseic acid 3’-O-b-gentiobioside, based on extensive NMR and MS spectral studies.
Keywords: white currant; seeds; sesquiterpenoid glucoside;
dihydrophaseic
acid derivative; indole derivative; 2D NMR.
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2011. Cited by
J. Serb. Chem. Soc. 76 (11) 1471–1483 (2011)
UDC Conium
maculatum:620.266.1:547.92:543;
JSCS–4221; doi: 10.2298/JSC110206128R; Original scientific paper
Steroids from poison hemlock (Conium maculatum L.): a GC–MS analysis
NIKO S. RADULOVIĆ and NEVENKA D. ĐORĐEVIĆ
Department of Chemistry,
Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000
Niš, Serbia
(Received 6 February, revised 16 March 2011)
The steroid
content of Conium maculatum L. (poison hemlock), Apiaceae, a well-known
weed plant species, was studied herein for the first time. This was achieved by
detailed GC–MS analyses of twenty two sAMples (dichloromethane extracts of
different plant organs of C. maculatum
at three or four different stages of phenological development, collected from
three locations). In total, twenty four different steroids were identified. Six steroids had
an ergostane nucleus while the other ones possessed a stigmastane carbon
frAMework. The identity of these compounds was determined by spectral
means (MS fragmentation), GC co-injections with authentic standards and
chemical transformation (silylation). Steroid compounds were noted to be the
main chemical constituents of root extracts (up to 70 %) of this plant species in
the last phase of development. The predominant ones were stigmasta-5,22-dien-3b-ol (stigmasterol) and stigmast-5-en-3b-ol (b-sitosterol). In an attempt to classify the sAMples, principal component analysis
(PCA) and agglomerative hierarchical clustering (AHC) were performed using
steroid percentages as variables.
Keywords: Conium maculatum L.; Apiaceae; GC–MS analyses; steroids; stigmasterol; b-sitosterol.
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J. Serb. Chem. Soc. 76 (11) 1485–1496 (2011)
UDC Phymatopteris hastata:547.56:547.972:615.27–188; JSCS–4222; doi: 10.2298/JSC101111130S; Original scientific paper
Phenolic content and antioxidant
activity of Phymatopteris hastata
WEI SU, PEIYUAN LI*, LINI
HUO*, CAIYING WU, NANA GUO and LIANGQUAN LIU
College of Chemistry and
Life Science, Guangxi Teachers Education University, Nanning, China
*College of Pharmacy,
Guangxi Traditional Chinese Medical University, Nanning, China
(Received 11 November 2010, revised 11 January 2011)
Various solvent extracts of Phymatopteris
hastata, a traditional Chinese medicinal material, were screened for their
antioxidant activities. Four systems of in
vitro testing were employed to investigate the antiradical and antioxidant
effect, i.e., the
2,2-diphenyl-1-picryhydrazyl (DPPH) and 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic
acid) (ABTS) systems, the hydroxyl radical scavenging assay and the reducing
power. In addition, butylated hydroxytoluene (BHT), a widely used synthetic
antioxidant, was also studied for comparison. The results revealed that the
ethyl acetate extract exhibited outstanding antioxidant activities, which was
close or even superior to BHT. Furthermore, the total phenolic
(TP) and total flavonoid (TF) contents of different extracts were measured,
expressed as gallic acid and rutin equivalent,
respectively. The antioxidant activities and the TP/TF content of different extracts followed the sAMe order: ethyl
acetate extract > butyl alcohol extract > petroleum
ether extract, showing a good correlation between the antioxidant activities
and the TP/TF content. The results showed that these extracts, especially the
ethyl acetate extract, were rich in phenolics and flavonoids and could be
considered as natural antioxidants.
Keywords: total phenolic content;
total flavonoid content; DPPH; ABTS; hydroxyl radical; reducing power; Phymatopteris hastata.
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2011. Cited by
J. Serb. Chem. Soc. 76 (11) 1497–1504 (2011)
UDC
66.017:547.831’269.3:544.553.537.004.12; JSCS–4223; doi: 10.2298/JSC110129127W; Original scientific pape
The synthesis, structure and photoluminescence property
of a novel 3D suprAMolecular compound based on mixed ligands of
8-hydroxyquinoline-5-sulfonate and ethylenediAMine
YING WANG*,**, CHANGFU ZHUANG*, CHUNHUA
WU*, JIAYAN ZHANG*,
LI WANG**, MINGHONG XIN**, GUANGSHAN ZHU** and JIANING XU**
*Southwest Forestry University,
Kunming, 650224, P. R. China
**State Key Laboratory of
Inorganic Synthesis and Preparation, Jilin University, Changchun, 130012, P. R. China
(Received 29 January, revised 29 September 2011)
A new organic–inorganic hybrid
coordination compound ZnQS(en)·2H2O (1)
in which two different organic ligands, ethylenediAMine (en) and 8-hydroxyquinoline-5-sulfonic acid (H2QS) coordinate with zinc ions, has been synthesized via the
evaporation method
and characterized by single crystal X-ray diffraction
analysis, IR spectroscopy and thermogravimetric analysis (TGA). The structure
solution showed
that compound
1 displays a three-dimensional suprAMolecular network by synergic linkage of hydrogen and
coordinated bonds. Moreover, compound 1
exhibits intense photoluminescence at 513 nm excited at 396 nm in the solid
state at room temperature.
Keywords: organic–inorganic hybrid material; 8-hydroxyquinoline-5-sulfonic
acid; photoluminescence
property.
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2011. Cited by
J. Serb. Chem. Soc. 76 (11) 1505–1511 (2011)
UDC 547.52/.53+66.095.252.5:54.02;
JSCS–4224; doi: 10.2298/JSC110224131G; Original scientific paper
A simple mathematical model for the effect of
benzo-annelation on cyclic conjugation
IVAN GUTMAN and AlEXANDRU T. BALABAN*
Faculty of Science,
University of Kragujevac, P. O. Box 60, 34000 Kragujevac, Serbia
*Texas A &AMp; M University at Galveston,
200 Seawolf Parkway, Galveston, TX 77553, USA
(Received
28 February 2011)
In a series of earlier studies, it was
established that benzo-annelation in the angular (resp. linear) position
relative to a ring R of a polycyclic conjugated p-electron system, increases (resp.
decreases) the intensity of the cyclic conjugation in the ring R. Herein, it is shown how
this regularity can be explained by means of a simple, Kekulé-structure-based
argument, itself based on an idea of Randić from the 1970s.
Keywords: cyclic conjugation; Kekulé structure; benzo-annelation; local aromaticity.
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2011. Cited by
J. Serb. Chem. Soc. 76 (11)
1513–1522 (2011)
UDC
547.48+66.094.3+547.857.8+546.215+546–328:544.4; JSCS–4225; doi: 10.2298/JSC100920135S; Original scientific paper
A green, reusable and highly efficient solid acid
catalyst for the oxidation of aldehydes to the corresponding carboxylic acids
using H2O2 and KMnO4:H5PV2Mo10O40
(10-molybdo-2-vanadophosphoric heteropolyacid)
ABDOLLAH FALLAH SHOJAEI,
MOHAMAD ALI REZVANI and MAJID HERAVI*
Department of Chemistry,
Faculty of Science, University of Guilan, Rasht 419961-3769, Iran
*Department of Chemistry,
School of Science, Azzahra University, Vanak, Tehran, Iran
(Received 20 September 2010, revised 23 May 2011)
H5PV2Mo10O40-catalyzed
oxidation of aromatic aldehydes to the corresponding carboxylic acids using
hydrogen peroxide and KMnO4 as oxidants under mild conditions is
reported. This system provides an efficient, convenient and practical method
for the oxidation of aromatic aldehydes. In this work, differences between
Keggin and Well–Dawson type polyoxometalates are addressed in term of relative
stability, hardness and acidity.
Keyword: heteropolyacids;
aldehydes; carboxylic acids; microwave irradiation; polyoxometalates.
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J. Serb. Chem. Soc. 76 (11)
1523–1536 (2011)
UDC
547.262+66.094.3+546.92+546.811+546.96+546.97:544.4+539.12; JSCS–4226; doi: 10.2298/JSC110217136L; Original scientific paper
Impact of the modification of carbon-supported,
Pt-based catalysts by irreversibly adsorbed Sn, Ru and Rh on ethanol oxidation
JELENA D. LOVIĆ, AMALIJA V.
TRIPKOVIĆ and KSENIJA DJ. POPOVIĆ
ICTM – Institute of
Electrochemistry, University of Belgrade, Njegoševa 12, P. O. Box 473, 11000
Belgrade, Serbia
(Received 17 February, revised 7 April 2011)
The oxidation of ethanol was studied
at Snad-, Ruad- and Rhad-modified and
unmodified PtC, Pt3Sn/C and Pt3Ru2/C
catalysts. PotentiodynAMic, quasi-steady-state and
chronoAMperometric measurements were used to investtigate the activity and
stability of the catalysts.
Irreversible adsorption of a small AMount of each of the adatoms (≈10 % surface coverage) enhanced
the activity of the Pt/C and Pt3Sn/C catalysts. The onset potential
was shifted by ≈50 mV towards lower values and the
current densities over the whole studied potential region were up to two times
higher with respect to the unmodified catalysts. On the other hand, the
addition of Snad or Rhad slightly increased the activity
of Pt3Ru2/C,
while the presence of Ruad decreased its activity for ethanol
oxidation. The catalytic action of Snad and Ruad was
associated mostly with their ability to adsorb oxygen-containing species at
lower potentials than Pt, permitting a bifunctional mechanism to proceed. Rhad
also acted on the C–C bond breaking activation as well as source of oxygen
containing species, increasing in this way the activity of the modified
surfaces for ethanol oxidation.
Keywords:
ethanol oxidation; Pt nanocatalyst; Pt–Sn nanocatalyst; Pt–Ru nanocatalyst;
Pt–Rh nanocatalyst; adatom modification.
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2011. Cited by
J. Serb. Chem. Soc. 76 (11)
1537–1550 (2011)
UDC 546.47’73:544.642.076.2:544.654.2:620.193;
JSCS–4227; doi:
10.2298/JSC110331137B;
Original scientific paper
Microstructure and corrosion behaviour
of Zn–Co alloys deposited from three different plating baths
JELENA B. BAJAT, SANJA I.
STEVANOVIĆ* and BOJAN M. JOKIĆ
Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia
*ICTM – Institute of Electrochemistry, University of Belgrade, Njegoševa 12, 11001 Belgrade, Serbia
(Received 31 March, revised 4 July 2011)
The effects of plating baths of different composition on the
microstructure and corrosion stability of Zn–Co alloy coatings were studied.
Zn–Co alloys with the sAMe Co content were deposited from chloride plating
baths containing different AMounts of Co2+, as well as from a
sulphate–chloride plating bath. The surface morphology and crystallite size
were investigated by scanning electron microscopy (SEM) and atomic force
microscopy (AFM). The corrosion stability of the Zn–Co alloys was determined by
following the change of the open circuit potential with time of immersion in a
3 % NaCl solution and by polarization measurements. The results showed a
significant influence of the plating bath on the morphology and corrosion
stability of the Zn–Co alloys. The surface of the alloy coatings deposited from
the chloride baths were uniform and homogenous, whereas the deposit obtained
from the sulphate–chloride bath was quite inhomogeneous. The corrosion
stability of the homogenous Zn–Co deposits obtained by deposition from both
chloride baths was higher than that of the deposit obtained from the
sulphate–chloride bath. An increase in the Co content in the chloride-plating
bath resulted in a reduction of the alloy crystallite size and it was shown
that the alloy with the smaller
crystallites of the two alloy deposits, although having the sAMe
chemical content, exhibited a lower
corrosion rate.
Keywords: electrodeposition; coatings; Zn–Co alloy; corrosion; AFM.
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2011. Cited by
J. Serb. Chem. Soc. 76 (11)
1551–1560 (2011)
UDC
577.112.385+547.431:543.4/.5+546.15+547.564.4’175.5:615; JSCS–4228; doi: 10.2298/JSC101007138R; Short communication
SHORT COMMUNICATION
Optimized and validated spectrophotometric methods for
the determination of hydroxyzine hydrochloride in pharmaceuticals and urine
using iodine and picric acid
NAGARAJU RAJENDRAPRASAD,
KANAKAPURA BASAVAIAH and KANAKAPURA B. VINAY
Department of Studies in Chemistry,
Manasagangothri, University of Mysore, Mysore 570 006, India
(Received 7 October 2010, revised 9 February 2011)
Two simple, rapid, cost-effective and sensitive spectrophotometric
procedures are proposed for the determination of hydroxyzine dihydrochloride
(HDH) in pharmaceuticals and in spiked human urine. The methods are based on
the charge transfer complexation reaction of the drug with either iodine (I2) as a s-acceptor (method A) in dichloromethane or picric acid (PA) as a p-acceptor (method B) in chloroform. The coloured products exhibit
absorption maxima at 380 and 400 nm for I2 and PA, respectively. The
Beer Law was obeyed over the concentration ranges of 1.25–15 and 3.75–45 mg mL-1 for method A
and B, respectively. The molar absorptivity values, Sandell sensitivities,
limits of detection (LOD) and
quantification (LOQ) are reported.
The accuracy and precision of the methods were evaluated on intra-day and
inter-day basis. The proposed methods were successfully applied for the determination
of HDH in tablets and spiked human urine.
Keywords: hydroxyzine dihydrochloride; determination; spectrophotometry;
charge-transfer complexation; pharmaceuticals; spiked urine.
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J. Serb. Chem. Soc. 76 (11)
1561–1566 (2011)
UDC 546.46+549.623:548.2:535.004.12; JSCS–4229; doi: 10.2298/JSC100818134G; Original scientific paper
The growth of Mg2TiO4 single
crystals using a four-mirror furnace
ALEKSANDAR GOLUBOVIĆ and MARKO RADOVIĆ
University of Belgrade, Institute
of Physics, Pregrevica 118, P. O. Box 68, 11080 Belgrade-Zemun, Serbia
(Received 18 August 2010, revised 9 February 2011)
A single crystal of Mg2TiO4 was grown by the
travelling solvent float zone (TSFZ) method. The lattice parAMeter a = 0.8444(8) nm was determined by X-ray
powder diffraction analysis. The optical properties of the Mg2TiO4
single crystals were studied using spectroscopic ellipsometry. The obtained
results are discussed and compared with published data.
Keywords: Mg2TiO4;
crystal growth; single crystal; four-mirror furnace; spectroscopic ellipsometry
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J. Serb. Chem. Soc. 76 (11)
1567–1581 (2011)
UDC 665:536.421.3:536.5:536.655; JSCS–4230; doi: 10.2298/JSC100813133B; Original scientific paper
An analytical study of the effects of vaporization of two-dimensional lAMinar
droplets on a triple flAMe
MEHDI BIDABADI, GHAZAL
BARARI and MILAD AZIMI
Combustion
Research Laboratory, Department of Mechanical Engineering; Iran University of
Science and Technology, Tehran, Iran
(Received 13 August 2010, revised 10 January 2011)
The structure of triple flAMe propagation in combustion systems,
containing uniformly distributed volatile fuel droplet was analyzed. The
analysis was established for a one-step irreversible reaction with an
asymptotic limit, where the value of the Zeldovich number is large. Here, using
unit Lewis number, the analytical results for the triple flAMe temperature were
obtained considering two sections. In the first section, a non-vaporizing fuel
streAM was studied and in the second section, a volatile droplet fuel streAM
was taken into account. It is presumed that the fuel droplets vaporize to yield
a gaseous fuel of known chemical structure, which is subsequently oxidized in
the gaseous phase. Here two different cases are studied. In the first case,
only the velocity parallel to the reactant flow was considered; while for the
latter one, the vertical velocity was considered in addition. The energy
equations were solved and the temperature field equations are presented. The
results are first presented for a non-vaporizing fuel and compared to the
experiment results. In addition, some other results of the temperature field
for a vaporizing fuel streAM are demonstrated within the comparison between the
above-mentioned cases which revealed the effect of the considering the vertical
velocity component on the flAMe temperature field.
Keywords: triple-flAMe; volatile
droplet; flAMe temperature.
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J. Serb. Chem. Soc. 76 (11)
1583–1595 (2011)
UDC
544.032.72+669.73+669.3/.4:504.45+504.73+504.53:543.421; JSCS–4231; doi: 10.2298/JSC101024139S; Original scientific paper
Preconcentration and determination of heavy metals in water, sediment
and biological sAMples
HAMID SHIRKHANLOO, HASSAN ZAVVAR MOUSAVI* and AHMAD ROUHOLLAHI
Department
of Chemistry, Faculty of Science, K. N. Toosi University of Technology,
Tehran, Iran
*Chemistry Department, College of Sciences, Semnan
University, Semnan, Iran
(Received 24 October 2010, revised 4
January 2011)
In this study, a simple, sensitive and accurate column
preconcentration method was developed for the determination of Cd, Cu and Pb
ions in river water, urine and sediment sAMples by flAMe atomic absorption
spectrometry. The procedure is based on the retention of the analytes on a
mixed cellulose ester membrane (MCEM) column from buffered sAMple solutions and
then their elution from the column with nitric acid. Several parAMeters, such
as pH of the sAMple solution, volume of the sAMple and eluent and flow rates of
the sAMple were evaluated. The effects of diverse ions on the preconcentration
were also investigated. The recoveries were >95 %. The developed method was
applied to the determination of trace metal ions in river water, urine and
sediment sAMples, with satisfactory results. The 3d detection limits for Cu, Pb and Cd were found to be
2, 3 and 0.2 μg dm-3 respectively. The presented procedure was
successfully applied for determination of the copper, lead and cadmium contents
in real sAMples, i.e., river water
and biological sAMples.
Keywords: lead; copper; cadmium; mixed cellulose ester
membrane; preconcentration.
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Copyright &AMp; copy; SHD 2011.
November 12, 2011.
For more information contact: JSCS-info@shd.org.rs