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.



 


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