J. Serb. Chem. Soc.
62(7) 535-539 (1997)
UDC
547.551.42:543.42/.51
JSCS-2417
Original
scientific paper
Substituent effect on C=O stetching vibrations in N-substituted
2-phenylacetamides
G. S. USCUMLIC, N. D. STOJANOVIC and S. D. PETROVIC
Department of Organic Chemistry, Faculty of Technology and
Metallurgy, University of Belgrade, YU-11001 Belgrade, P. O. Box 494, Belgrade,
Yugoslavia
(Received
4 November 1996, revised 10 March 1997)
The infrared spectra have been recorded for
the N-substituted 2-phenylacet-amides. The effect of substitutents on
the spectral characteristics of the C=O group was investigated. When the
electron-releasing substitutents are attached to the nitrogen atom, substituent
effects are transmitted to the C=O group by the usual mechanism. However, the
effect of electron-withdrawing substituents appears to be quite opposite,
i.e., the carbonyl stretching vibrations are decreased. FT-IR data related
to C=O stretchning frequencies are correlated with the sample Hammett equation QX = sr + h and with the extended
Hammett equation QX=asl+bsR+h. These correlations
were interpreted in view of the transmission of electronic effects of the
substitutents through the amide bond.
Key
words: N-substituted 2-phenylacetamides, infrared spectra, stretching
frequencies, substituent effects, Hammett equation.
J. Serb. Chem. Soc. 62 (7) 541-549 (1997)
UDC
547.269.532.1:547.772/.779:66.095.25
JSCS-2418
Original
scientific paper
Heterocyclization of sulphamido chalcones to pyrazoline,
cyanopyridone, nicotinonitrile and hydrobenzo[1,2-c]pyrazole derivatives
H. A. EMAM, S. M. HASSAN and A. A. EL-MAGHRABY
Department of Chemistry, Faculty of Science, Al-Azhar
University, Nasr City, Cairo, Egypt
(Received
20 December 1996)
3-Cyano-4,6-disubstituted pyridone and
2-cyclohexene ester derivatives VII, X were prepared from chalcones II; further
reactions of VII with POCl3/PCl5 then with NaN3 led to chloronicotinonitrile and tetrazolopyridine derivatives
VIII and IX; while the reaction of X with hydrazines followed by Ac2O and/or a hot mixture
of H2SO4-AcOH afforded tetrahydrobenzo[1,2-c]pyrazolone,
hexahydrobenzo[1,2]pyrazole and cyclohexenone derivatives XI, XII and XIII,
respectively. Enaminonitrile VI was prepared from I and 4-methyl-a-cyanocinnamonitrile.
Key
words: heterocyclization, sulphamido chalcones, pyrazioline, cyanopyridone,
nicotinonitrile, pyrazole, derivatives of.
J. Serb. Chem. Soc. 62(7) 551-555 (1997)
UDC
547.722/.728:547.455.643
JSCS-2419
Short
communication
SHORT COMMUNICATION
Formation
of 3,6-anhydro-D-glucofuranosides in an acid-catalysed alcoholysis of partially
tosylated D-glucose derivatives
EVGENIJA A. DJURENDIC, MIRJANA POPSAVIN, SMILJANA VELIMIROVIC,
NADA VUKOJEVIC, BILJANA PERIC, VELIMIR POPSAVIN and DUŠAN MILJKOVIC
Institute of Chemistry, Faculty of Science, University of Novi
Sad, Trg D. Obradovica 3, YU-21000 Novi Sad, Yugoslavia
(Received
7 November 1996)
Partial esterification of D-glucose with 2
moles of tosyl chloride in pyridine at 14°C gave 2,6-di-O-p-toluenesulphonyl-D-glucopyranose
(1) as the main reaction product (55%) and 6-O-p-toluenesulphonyl-D-glucopyranose
(2) as the minor product (33%). The reaction of D-glucono-1,5-lactone (3)
with 5 moles of tosyl chloride in pyridine at -10 °C gave the corresponding
2,6-di-O-tosyl derivative 4 (62%), which was further treated with
sodium borohydride in DMSO, at room temperature, to afford compound 1 in
95% yield. Acid catalysed alcoholysis of 1 in refluxing methanol or
ethanol gave low yields of the corresponding 3,6-anhydro-D-glucofuranosides 5
(25%) and 6 (27%). However, the reaction of 1 with benzyl alcohol
(130°C) in the presence of toluene-p-sulphonic acid as a catalyst
afforded the corresponding 3,6-anhydro-D-glucofuranoside 7 in an acceptable
yield of 45%.
Key
words: alcoholysis, 3,6-anhydro-sugars, D-glucono-1,5-lactone, D-glucose,
partial tosylation.
J. Serb. Chem. Soc. 62(7) 557-564 (1997)
UDC
C60:540.2121:66.091
JSCS-2420
Original
scientific paper
Optimization of the operational parameters in fullerene
production
Z. MARKOVIC, T. JOKIC, B. TODOROVIC-MARKOVIC, J. BLANUSA* and T.
NENADOVIC
Atomic Physics Laboratory and *Laboratory for Theoretical and
Condensed-Matter Physics,
Vinca Institute of Nuclear Sciences, P. O.
B. 522, YU-11001 Belgrade, Yugoslavia
(Received
5 November 1996, revised 1 April 1997)
The process of fullerene formation and
production was studied in terms of the operational parameters of the DC arc
discharge between graphite electrodes in the presence of helium. The effects of
the gas pressure and direct current on the fullerene yield were investigated. A
maximum fullerene yield of 8% was found in the raw soot after evaporation of
graphite with 60 A direct current under a helium pressure of 8 kPa. The
fullerenes were characterized by UV spectroscopy, mass spectroscopy and X-ray
diffraction. Typical data obtained with used techniques are shown.
Key
words: fullerene, synthesis.
J. Serb. Chem. Soc. 62(7) 565-573 (1997)
UDC
614.7/.777:543.544.2/.25:549.88
JSCS-2421
Original
scientific paper
Application of the unified retention data in environmental
analysis
BILJANA D. SKRBIC and LJUBINKA S. PAVIC-SUZUKI
Faculty of Technology, University of Novi Sad, Bulevar cara
Lazara, YU-21000 Novi Sad, Yugoslavia
(Received
11 October 1996)
A unified retention concept was developed
based on the enhanced gas chromatographic identification of a significant
number of hydrocarbon pollutants in the envi- ronment. This paper briefly
describes the advantages of the unified retention concept showing some
potential applications in the chemical and petrochemical industries,
combustion, waste treatment and disposal.
Key
words: application, unified retention data, environmental analysis,
squalane, methylsilicone stationary phases.
J. Serb. Chem. Soc. 62(7) 575-579 (1997)
UDC
614.7:543.544.25:549.88
JSCS-2422
Original scientific
paper
Unified retention indices of
hydrocarbons on dinonylphthalate phase
BILJANA D. SKRBIC
Faculty of Technology, University of Novi Sad, Bulevar cara
Lazara, YU-21000 Novi Sad, Yugoslavia
(Received
11 October 1996)
Gas chromatographic unified retention
indices are obtained for 52 hydrocarbons on dinonylphthalate stationary phase.
The calculated values agree well with the corresponding experimental values
taking into account the statistical treatment of the experimental data.
Key
words: unified retention data, hydrocarbons, dinonylphthalate stationary
phase, statistical treatment.
J. Serb. Chem. Soc. 62 (7) 581-590 (1997)
UCC
546.817/546.131'14''/:541.428.49
JSCS-2423
Original
scientific paper
Cationic lead(II) chloride and bromide complexes in molten Ca(NO3)2·4,7H2O
ISTVAN J. ZSIGRAI and SLOBODAN B. GADZURIC
Institute of Chemistry, Faculty of Science, University of Novi
Sad, YU-21000, Novi Sad, Yugoslavia
(Received
24 December 1996, revised 24 March 1997)
The complex formation between lead (II)
ions and chloride and bromide ions in molten Ca(NO3)2·4,7H2O has been studied by
emf and solubility measurements in the temperature range 50 ± 80°C. The
formation constants of the complexes PbX+ and PbX2 were determined from emf measurements by means of Ag, AgX (X =
Cl, Br) electrodes in suitable concentration cells, at lead (II) and halide
concentration low enough to avoid PbX2 precipitation. From solubility data in the concentration range
cPb >
cx/2,
the solubility product of PbX2 and the formation constants for the complexes Pb2X3+, PbX+ and PbX2 were determined. The
thermodynamic parameters DHo and DSo for the dissolution of solid PbX2 and for the stepwise
formation of the complexes PbmXn2m-n have been evaluated. A
comparison of DHo and DSo for PbX+ formation with the literature data for the same process in
dilute aqueous solutions and anhydrous and aqueous melts indicates that the
complex formation process in aqueous melts is similar to that in anhydrous
melts.
Key
words: aqueous melts, calcium nitrate, complex, lead(II) bromide, lead(II)
chloride.
J. Serb. Chem. Soc. 62(7) 591-598 (1997)
UDC
549.67/54-114/-546.763
JSCS-2424
Original
scientific paper
Ion exchange of synthetic zeolite A with Cr(III) ions
NEVENKA RAJIC and JELICA NOVAKOVIC
Faculty of Technology and Metallurgy, University of Belgrade,
Karnegijeva 4, YU-11000 Belgrade, Yugoslavia
(Received
20 September 1996, revised 20 February 1997)
A series of chromium-exchanged zeolite A
was prepared by ion-exchange using very dilute solution of a chromium(III)
salt. The chromium(III) ions can replace up to 40% sodium cations. A
significant lattice decomposition was found at higher chromium exchange levels.
Chemical, X-ray diffraction, and thermal analyses were made and data on the
composition and the unit cell dimensions are reported. The diffuse reflectance
spectra of the as-made and the dehydrated chromium-exchanged zeolite A were
investigated. In the as-made product chromium(III) is octahedrally coordinated
whereas after dehydration its coordination number decreases.
Key
words: chromium-exchanged zeolite A; chromium(III) coordination;
ion-exchan-ge; X-ray diffraction; DSC analysis; diffuse reflectance
spectroscopy.
J. Serb. Chem. Soc. 62(7) 599-605 (1997)
UDC
547.295.72/547.233.1/:549.657.13
JSCS-2425
Original
scientific paper
Interaction of dodecylamine with montmorillonite.
Part I. Adsorption mechanism
ALEKSANDRA VUJAKOVIC, MAGDALENA TOMASEVIC-CANOVIC and VERA
DONDUR*
Institute of Technology of Nuclear and Other Mineral Raw
Materials, Franše d'Epere 86, P.O.Box 390, YU-11000 Belgrade, Yugoslavia, Fax
011/647-672 and
*Faculty of Physical Chemistry, University
of Belgrade, P.O.Box 137, YU-11001 Belgrade, Yugoslavia
(Received
6 December 1996, revised 14 March 1997)
It was observed that dodecylamine
adsorption on Na-montmorillonite occurred as the cation exchange of Na+ ion by dodecylammonium
ion, up to the dodecylamine addition of 70 mmol/z.100g clay. The results of
particle size distribution analysis showed that increasing concentration of
adsorbed dodecylamine was followed by increasing particle size in suspension.
IR spectra of organoclay complexes showed the bands in the range 1490-1465 cm-1 corresponding to
dodecylammonium ion chemisorbed on the silicate surfaces of montmorillonite.
Key
words: adsorption, montmorillonite, dodecylamine, organoclay complex, cation
exchange.
J. Serb. Chem. Soc. 62(7) 607-613( 1997)
UCC
547.295.72/547.233.1/:549.657.13
JSCS-2426
Original scientific
paper
Interaction of dodecylamine with montmorillonite:
Part II. Structural aspects
ALEKSANDRA VUJAKOVIC, MAGDALENA TOMASEVIC-CANOVIC, MILUTIN DUMIC
and MIRJANA DJURICIC
Institute of Technology of Nuclear and Other Mineral Raw
Materials, Franše d'Epere 86, P.O. Box 390, 11000 Belgrade, Yugoslavia
(Received
6 December 1996, revised 14 March 1997)
The structural aspects of a series of
dodecylamine/montmorillonite complexes were examined by TG/DTA, XRD and SEM
study. TG/DTA analysis showed two-stage degradation of interlayered organic
substance at 200-500°C and 500-800°C. It was observed that the presence of
organic molecules on the clay surface caused an increase in its hydrophobicity.
The X-ray patterns showed an increase in the basal spacings of montmorillonite
caused by the intercalation of dodecylamine. The basal spacings correspond to
parallel orientation of dodecyl chains.
Key
words: adsorption, montmorillonite, organoclay complex, dodecylamine, cation
exchange.
J. Serb. Chem. Soc. 62(7) 615-618 (1997)
UDC C60:542.92:543.875
JSCS-2427
Note
NOTE
Thermochemical
behavior of C60. Kinetics of decomposition in different atmospheres
SLAVISA M. SIMIC and ALEKSANDAR B. DEVECERSKI
Faculty of Physical Chemistry, University of Belgrade, P.O. Box
137, YU-11001 Belgrade, Yugoslavia
(Received
22 October 1996, revised 25 March 1997)
The processes of decomposition of C60 in different atmospheres
were investigated by TG and DTG methods. It was observed that the temperature
maxima on the DTG curves are shifted towards higher temperatures by about 200 K
in an inert nitrogen atmosphere compared to the values in air. Kinetic
parameters were calculated by methods evaluated for processes under
nonisothermal conditions. In air, where oxidation takes place, the values of
the activation energy depending on the method used, are: Ea =145+6 kJ/mol
(Freeman-Carroll), Ea= 138+16 kJ/mol (Ozawa), Ea = 121+14 kJ/mol
(Kissinger). In nitrogen, where sublimation occurs, the values of the
activation energy are: Ea = 130+8 kJ/mol (Freeman-Carroll). Ea=157+16 kJ/mol
(Ozawa), Ea = 141+14 kJ/mol (Kissinger).
Key
words: C60, fullerenes; kinetics, decomposition.