JSCS Vol 73, No. 12
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J. Serb. Chem. Soc. 73 (12) 1139–1151 (2008)
UDC 547.521–326:542.913+577.15;
JSCS–3793; doi: 10.2298/JSC0812139K;
Original scientific paper
Lipase catalyzed synthesis of flavor
esters in non-aqueous media: Optimization of the yield of pentyl
2-methylpropanoate by statistical analysis
ZORICA KNEZEVIC-JUGOVIC, DEJAN BEZBRADICA, ZIVANA JAKOVLJEVIC*, SUZANA
BRANKOVIC-DIMITRIJEVIC and DUSAN MIJIN
Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4,
11120 Belgrade, Serbia
*Faculty of Mechanical Engineering, University of
Belgrade, Kraljice Marije 16, 11120 Belgrade, Serbia
(Received 19 March, revised 3 June 2008)
In this study, the synthesis of pentyl
2-methylpropanoate employing a commercial lipase from Candida rugosa was investigated, the emphasis being placed on
analyzing the effects of various process conditions on the yield of ester. The
response surface methodology (RSM) and five-level-five-factor central composite
rotatable design (CCRD) were used to evaluate the effects of variables, nAMely
the initial water content, 0.0–2.0 % (w/v), the reaction temperature, 35–75 °C,
the enzyme concentration, 1.0–5.0 g dm-3, the acid/alcohol mole
ratio, 1:2–5:2, and the reaction time, 4–48 h, on the yield (%) of ester. The
production of pentyl 2-methylpropanoate was optimized and an ester yield
response equation was obtained, enabling the prediction of ester yields from
known values of the five main factors. It seems that the enzyme concentration,
reaction time and acid/alcohol mole ratio predominantly determine the
conversion process, while the AMount of added water AMount had no significant
influence on the ester yield. Conversion of around 92 % of the substrate to
ester could be realized using a concentration of lipase as low as
4.0 g dm-3 and in a relatively short time (26 h) at 35 °C,
when a high substrate mole ratio of 2.5 was used.
Keywords: factorial design; surface response analysis; Candida rugosa lipase; flavor esters;
esterification.
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Article - PDF 466 KB
J. Serb. Chem. Soc. 73 (12) 1153–1160 (2008)
UDC 546.732+547.582.4:615.281–188;
JSCS–3794; doi: 10.2298/JSC0812153P;
Original scientific paper
Antibacterial activity of cobalt(II) complexes with
some benzimidazole derivatives
S. O. PODUNAVAC-KUZMANOVIC, V. M. LEOVAC* and D. D. CVETKOVIC
Faculty of Technology, Bul. Cara Lazara 1, 21000 Novi Sad, Serbia
*Department of Chemistry, Faculty of Sciences, Trg D.
Obradovica 3, 21000 Novi Sad, Serbia
(Received 21 March, revised 26 May 2008)
The antibacterial activities of cobalt(II) complexes
with two series of benzimidazoles were evaluated in vitro against three
GrAM-positive bacterial strains (Bacillus
cereus, Staphylococcus aureus,
and Sarcina lutea) and one
GrAM-negative isolate (Pseudomonas
aeruginosa). The minimum inhibitory concentration was determined for all
the complexes. The majority of the investtigated complexes displayed in vitro inhibitory activity against
very persistent bacteria. They were found to be more active against
GrAM-positive than GrAM-negative bacteria. It may be concluded that the
antibacterial activity of the compounds is related to the cell wall structure
of the tested bacteria. Comparing the inhibitory activities of the tested
complexes, it was found that the 1-substituted-2-AMinobenzimidazole derivatives
were more active than complexes of
1-substituted-2-AMino-5,6-dimethylbenzimidazoles. The effect of chemical
structure on the antibacterial activity is discussed.
Keywords: benzimidazole derivatives; complexes; cobalt(II);
antibacterial; in vitro studies.
Full Article - PDF 348 KB
J. Serb.
Chem. Soc. 73 (12) 1161–1167 (2008)
UDC 54+582.33:547.261:547.56; JSCS–3795;
doi: 10.2298/JSC0812161J; Original scientific paper
HPLC–DAD of phenolics in bryophytes Lunularia cruciata, Brachytheciastrum velutinum and Kindbergia
praelonga
NEBOJSA JOCKOVIC, PAULA B. ANDRADE*, PATRÍCIA VALENTÃO* and MARKO SABOVLJEVIC**
Institute of Pharmaceutical Biology,
Martin-Luther-University Halle-Wittenberg, Hoher Weg 8, 06120 Halle/Saale,
Germany
*Requimte, Institute of Pharmacognosy,
Faculty of Pharmacy, University of Oporto, Rua Aníbal Cunha, 4050-047, Porto,
Portugal
**Institute of Botany and Garden,
Faculty of Biology, University of Belgrade, Takovska 43, 11000 Belgrade, Serbia
(Received 27 March, revised 30 May 2008)
The
chemistry of bryophytes is not well known. The available data indicate
interesting chemical constitutions of some bryophyte species, i.e., active and
new compounds are to be found within bryophytes, especially liverworts. In this
study, one liverwort and two moss species were studied: Lunularia cruciata (L.) Dumort, Brachytheciastrum
velutinum (Hedw) Ignatov &AMp; Huttunen and Kindbergia praelonga (Hedw) Ochyra. The phenolic compositions of
these bryophyte species have not hitherto been reported. Their methanolic
extracts were analyzed by reversed-phase HPLC, coupled to a diode-array
detector (DAD). Luteolin-7-O-glucoside and quercetin were found in the L. cruciata extract. The extract
obtained from B. velutinum contained
four phenolic acids (4-O-caffeoylquinic, 5-O-caffeoylquinic, caffeic and
ellagic acids) and three flavonoids (apigenin-7-O-glucoside, luteolin and
apigenin). The K. praelonga extract
was characterized by the presence of several phenolic acids and their
derivatives (4-O-caffeoylquinic, 5-O-caffeoylquinic, caffeic, p-coumaric,
ferulic and ellagic acids, and caffeic and p-coumaric acid derivatives) and
three flavonoids (apigenin-7-O-glucoside, luteolin, apigenin and an
un-identified flavanone).
Keywords:
bryophytes; phenolics; Lunularia cruciata;
Brachytheciastrum velutinum; Kindbergia praelonga.
Full Article - PDF 384 KB
J. Serb. Chem. Soc. 73 (12) 1169–1180 (2008)
UDC 547.466.64+546.3+54–145.2:66.011;
JSCS–3796; doi: 10.2298/JSC0812169V;
Original scientific paper
Computer augumented modelling studies of
Pb(II), Cd(II), Hg(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of
L-glutAMic acid in 1,2-propanediol–water mixtures
MAHESWARA RAO VEGI, PADMA LATHA MUDDAPU, SIVA RAO TIRUKKUVALLURI and NAGESWARA
RAO GOLLAPALLI
School of Chemistry, Andhra University, VisakhapatnAM-530003, India
(Received 25 April 2007, revised 16 June
2008)
Chemical speciation of Pb(II), Cd(II), Hg(II), Co(II),
Ni(II), Cu(II) and Zn(II) complexes of L-glutAMic acid was studied at 303 K in
0–60 vol. % 1,2-propanediol–water mixtures, whereby the ionic strength was
maintained at 0.16 mol dm-3. The active forms of the ligand are LH3+,
LH2 and LH–. The predominant detected species were ML, ML2,
MLH, ML2H and ML2H2. The trend of the
variation in the stability constants with changing dielectric constant of the
medium is explained based on the cation stabilizing nature of the co-solvents,
specific solvent–water interactions, charge dispersion and specific
interactions of the co-solvent with the solute. The effect of systematic errors
in the concentrations of the substances on the stability constants is in the
order alkali > > acid > ligand > metal. The bioavailability and
transportation of metals are explained based on distribution diagrAMs and stability
constants.
Keywords: chemical speciation; L-glutAMic acid;
1,2-propanediol; bioavailability; metals.
Full Article - PDF 502 KB
UDC
544.354–128.4+547.545/.548:66.061:532.74; JSCS–3797; doi:
10.2298/JSC0812181M; Short
communication
SHORT
COMMUNICATION
Solvent extraction of Ca2+, Ba2+,
Cu2+, Zn2+, Cd2+, Pb2+, UO22+,
Mn2+, Co2+ and Ni2+ into nitrobenzene using
strontium dicarbol-lylcobaltate and tetra-tert-butyl p-tert-butylcalix[4]arene
tetraacetate
E. MAKRLÍK, J.
BUDKA*, P. VAŇURA* and P. SELUCKÝ**
Faculty of
Applied Sciences, University of West Bohemia, Husova 11, 306 14 Pilsen, Czech
Republic
*Institute of
Chemical Technology, Technická 5, 166 28 Prague, Czech Republic
**Nuclear
Research Institute, 250 68 Řež, Czech Republic
(Received 4 February, revised 26 May 2008)
The exchange extraction constants corresponding
to the general equilibrium M2+(aq) + SrL2+(nb) D ML2+ (nb) + Sr2+ (aq) occurring in the two-phase
water–nitrobenzene system (M2+ = Ca2+, Ba2+,
Cu2+, Zn2+, Cd2+, Pb2+, UO22+,
Mn2+, Co2+ or Ni2+; L = tetra-tert-butyl
p-tert-butylcalix[4]arene tetraacetate; aq = aqueous phase; nb =
nitrobenzene phase) were evaluated from extraction experiments and g-activity
measurements. Furthermore, the stability constants of the ML2+ complexes in
water saturated nitrobenzene were calculated; they were found to increase in
the cation order Ba2+ < Mn2+ < Pb2+, Co2+
< Cu2+, Zn2+ < Cd2+, Ni2+
< UO22+ < Ca2+.
Keywords: divalent cations; calix[4]arene compound;
extraction and stability constants; water–nitrobenzene system.
Full Article - PDF 364 KB
J. Serb. Chem. Soc. 73 (12) 1187–1196 (2008)
UDC 547.672:54.02:54–74:537.872; JSCS–3798; doi:
10.2298/JSC0812187W; Original scientific paper
Electronic structures and spectra of conducting anthracene derivatives
ZHONGFA WANG and SHI WU
Department of Chemistry,
Zhejiang University, Hangzhou 310027, PRC
(Received 20 June, revised 26 November 2007)
Theoretical studies on anthracene and a series of its
derivatives were performed using the AM1 method and DFT. Based on
B3LYP/6-31G(d) optimized geometries, the electronic, IR and NMR spectra of
anthracene oligomers were calculated using the Indo/Cis, AM1 and B3LYP/6-31G(d)
methods, respectively. The energy gaps of the oligomers decreased and the main
absorptions in the electronic spectra of the oligomers were red-shifted,
whereas the IR frequencies for some of the C=C and C–H bonds were blue-shifted
with increasing chain length and in the presence of substituents. The 13C-NMR
chemical shifts of the bridged carbon atoms were upfield shifted in the
presence of an electron-donating group, while the chemical shifts of the carbon
atoms on the two side rings of the anthracene moiety shifted downfield in the
presence of an electron-withdrawing group.
Keywords: anthracene; conducting
polymer; energy gap; chemical shift; B3LYP/6-31G(d).
Full Article - PDF 346 KB Supplementary Material - PDF 
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J. Serb. Chem. Soc. 73 (12) 1197–1209 (2008)
UDC 546.78–261+546.92:544.6.004.2; JSCS–3799; doi: 10.2298/JSC0812197O; Original
scientific paper
Electrochemical properties of mixed WC and
Pt-black powders
MAJA D.
OBRADOVIC, BILJANA M. BABIC*, ANDRZEJ KOWAL**, VLADIMIR V. PANIC and SNEZANA
LJ. GOJKOVIC***
Institute of
Chemistry, Technology and Metallurgy, University of Belgrade, Njegoseva 12,
11001 Belgrade, Serbia
*Vinča Institute
of Nuclear Sciences, P. O. Box 522, 11001 Belgrade, Serbia
**Institute of
Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8,
30-239 Krakow, Poland
***Faculty of
Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120
Belgrade, Serbia
(Received 7 July, revised 28 August 2008)
The electrochemical characteristics of a
mixture of Pt-black and WC powders and its catalytic activity for methanol and
formic acid oxidation were investigated in acid solution. XRD and AFM
measurements revealed that the WC powder employed for the investigation was a
single-phase material consisting of crystallites/spherical particles of average
size of about 50 nm, which were agglomerated into much larger particles. Cyclic
voltAMmetry showed that the WC underwent electrochemical oxidation, producing
tungstate species. In the case of the mixed Pt + WC powders, the tungstate
species were deposited on the Pt as a thin film of hydrous tungsten oxide.
Enhanced hydrogen intercalation in the hydrous tungsten oxide was observed and
it was proposed to be promoted in mixed powders by the presence of hydrogen
adatoms on bare Pt sites. The determination of Pt surface area in the Pt + WC
layer by stripping of underpotentially deposited Cu revealed that the entire Pt
surface was accessible for underpotential deposition of Cu. Investigation of
the electrochemical oxidation of methanol and formic acid on Pt + WC and pure
Pt layers did not indicate electrocatalytic promotion due to the presence of
WC.
Keywords: tungsten carbide; platinum; hydrogen
intercalation; methanol oxidation; formic acid oxidation.
Full Article - PDF 1.248 KB
J. Serb. Chem. Soc. 73 (12)
1211–1221 (2008)
UDC 546.82–31:544.773.42:544.5/.6.004.2;
JSCS–3800; doi: 10.2298/JSC0812211P; Original scientific paper
Photoelectrochemical
properties of sol–gel obtained titanium oxide
Institute of Chemistry,
Technology and Metallurgy, University of Belgrade, Njegoseva 12, 11001
Belgrade, Serbia
*Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia
(Received 2 July, revised
12 October 2008)
The photoelectrochemical
properties of a sol–gel prepared titanium oxide coating applied onto a Ti
substrate were investigated. The oxide coating was formed from an inorganic sol
thermally treated in air at 350 °C. The coating consisted of agglomerates of narrow
size distribution around 100 nm. The photoelectrochemical characteristics were
evaluated by investigating the changes in the open circuit potential, current
transients and impedance characteristics of a Ti/TiO2 electrode upon
illumination by UV light in H2SO4 solution and in the
oxidation of benzyl alcohol. The electrode was found to be active for
photoelectrochemical reactions in the investigated solutions.
Keywords: photoelectrochemical activity; titanium oxide;
oxide sol; sol–gel procedure; electrochemical impedance spectroscopy.
Full Article - PDF 534 KB
J. Serb. Chem. Soc. 73 (12)
1223–1233 (2008)
UDC
547.675+546.11.027:543.544.3:543.51:612.461; JSCS–3801, doi:
10.2298/JSC0812223X; Original scientific paper
Determination of
dimethoxyphenethylAMine derivatives in urine by deuterium labeled internal
standards
YA-ZHU XU, HUEI-RU LIN*, AHAI-CHANG LUA*,**
and CHINPIAO CHEN
Department of Chemistry, National
Dong Hwa University, Hualien 974, Taiwan, R. O. C.
*Institute of Medical
Sciences, Tzu Chi University, Hualien 970. Taiwan, R. O. C.
**Department of Laboratory
Medicine and Biotechnology, Tzu Chi University, Hualien 970, Taiwan, R. O. C.
(Received 4 February,
revised 21 June 2008)
The use of gas
chromatography–mass spectrometry (GC–MS) in forensic analysis is increasing. To
exploit fully the capabilities of MS, labeled standards, that can be used to
improve the performance of the quantitative analysis, and to increase accuracy
and precision, are required. A series of deuterated internal standards,
corresponding to the 2C-series of phenethylAMine derivatives, including
4-bromo-2,5-dimethoxyphenethylAMine-d6 (2C-B),
4-chloro-2,5-dimethoxyphenethylAMine-d6 (2C-C),
4-iodo-2,5-dimethoxy-phe¬nethyl-AMine-d6 (2C-I),
4-ethylthio-2,5-dimethoxy-phenethylAMine-d6 (2C-T-2) and
2,5-dimethoxy-4-n-propylthiophenethylAMine-d6 (2C-T-7), were
synthesized. These deuterated compounds were used to analyze for the corresponding
unlabeled compounds in urine. The analysis was performed using GC–MS, with the
selected ion monitoring (SIM) technique, whereby good results were achieved.
Keywords: phenethylAMine; designer drugs; 2C-C; 2C-B; 2C-I;
2C-T-2; 2C-T-7.
Full Article - PDF 481 KB
J. Serb. Chem. Soc. 73 (12)
1235–1246 (2008)
UDC
547.581.2+547.831–32:532.13:541.25; JSCS–3802; doi:
10.2298/JSC0812235R; Original scientific paper
Study of solute–solvent
interactions of nicotinic acid and benzoic acid in methanol and its binary
solvent systems
MAHENDRA NATH ROY, LOVELY
SARKAR and BIPUL KUMAR SARKAR
Department of Chemistry,
University of North Bengal, Darjeeling-734013, India
(Received 22 November 2007,
revised 23 April 2008)
The apparent molar volumes,
fV, and viscosity
B-coefficients, B, for nicotinic acid (NA) and benzoic acid (BA) in
mixed solvents containing 10, 20, 30 mass % of n-AMyl alcohol (n-AmOH)
or isoAMyl alcohol (i-AmOH) in methanol and in pure methanol (MeOH) were
determined from the solution density and viscosity measurements at 298.15 K as
function of concentrations of NA and BA. These results were, in conjunction
with the results obtained in pure methanol, used to deduce the partial molar
volumes of transfer, DfV0¹, and viscosity B-coefficients of transfer, DB, for NA
and BA from methanol to different mixed methanol solvents, in order to rationalize various
interactions in the ternary solutions. An increase in the transfer properties
of NA and BA with increasing mass % of n-AmOH and i-AmOH in methanol was
observed and explained by the effect of structural changes and preferential
solvation. Also, the free energies of viscous flow, Dm10¹ and Dm20¹, per mole of solvent and solute, respectively, were calculated and
analyzed on the basis of the transition state theory of relative viscosity.
Keywords: apparent molar volumes; viscosity B-coefficients;
nicotinic acid; benzoic acid; solute–solvent interactions.
Full Article - PDF 306 KB
J. Serb. Chem. Soc. 73 (12) 1247 (2008)
Errata (printed version only)
J. Serb. Chem. Soc. 73 (12) 1249–1257 (2008)
Contents of Volume 73
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J. Serb. Chem. Soc. 73 (12) 1259–1263 (2008)
Subject index
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J. Serb. Chem. Soc. 73 (12) 1265–1269 (2008)
Author index
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Article - PDF 119 KB
End of Vol 73
Copyright
&AMp; copy; SHD 2008.
November 29, 2008.
For more information contact: JSCS@tmf.bg.ac.rs