J. Serb. Chem. Soc. 62 (12) 1143-1149(1997)
UDC 66.095.252:547.265
JSCS-2486
Original scientific paper

Intramolecular cyclisation of 4-tert-butyl-penten-1-ol with electrophilic reagents 1-3

MIHAILO Lj. MIHAILOVIC, SVETISLAV GOJKOVIC*, SLOBODAN MILOSAVLJEVIC
and STANIMIR KONSTANTINOVIC**

Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, P.O.Box 158, YU-11001 Belgrade, Yugoslavia,
*Institute of Chemistry, Technology and Metallurgy, Njegoseva 12, YU-11000 Belgrade, Yugoslavia,
**Department of Chemistry, Faculty of Science, University of Kragujevac, P. O. Box 60, YU-34000 Kragujevac, Yugoslavia

(Received 16 May 1997)
In the acid (H2SO4) catalysed reaction of 4-tert-butyl-4-penten-1-ol (3), the products of 1,2-methyl rearrangement were obtained (the tetrahydripyran-type ether 8 and the aldehyde 9). The "normal" and rearranged cyclisation products 7 and 8 were formed in approximately equal amounts (34% and 36%, respectively), while the open-chain aldehyde with a rearranged skeleton 9 was also formed in significant yield (29%). The oxymercuration/demercuration reaction of 3 and its reaction with meta-chloroperbenzoic acid afforded in high yields exclusively Markovnikov-type products, i.e., the THF ether 7 and the THF-hydroxy ether 17.

Key words: intramolecular cyclisation, 4-tert-butyl-4-pentenl-ol, electrophilic regents.




J. Serb. Chem. Soc. 62(12) 1151-1156 (1997)
UDC  547.514.71:542.9
JSCS-2487
Original scientific paper
 

A simple synthetic route to 2,2,5-trimethyl-4-cyclohepten-1-one (karahanaenone) starting with linalool

STANIMIR KONSTANTINOVIC* **, ZORICA BUGARCIC*, LJILJANA MARJANOVIC*,
SVETISLAV GOJKOVIC***, and MIHAILO  LJ. MIHAILOVIC*** ****

*Department of Chemistry, Faculty of Science, University of Kragujevac, P.O.Box 60, YU-34000 Kragujevac, Yugoslavia,
**Max-Planc-Institut fuer Kohlenforschung, P.O.Box 101353, D-45466, Muelheim - Ruhr, Germany,
***Institute of Chemistry, Technology and Metallurgy, Njegoseva 12, YU-11000 Belgrade,
****Faculty of Chemistry, University of Belgrade, P.O.Box 158, YU-11001 Belgrade, Yugoslavia

(Received 2 July 1997)
2,2,5-Trimethyl-4-cyclopten-1-one (karahanaenone) (1) has been prepared from linalool (3) was cyclized to the corresponding tetrahydrofuran-type cyclic ether 4 by means of PhSeCl, N-bromosuccinimide, or 3-chloropenbenzoic acid. On treatment with various regents, the cyclic ether 4 provided the cyclic ether 6 which was converted to 1 via 2.

Key words: karahanaenone synthesis of, linalool, PhSeCl, NBS, 3-chloroperbenzoic acid. 




J. Serb. Chem. Soc. 62(12) 1157-1165 (1997)
UDC 547.514.71:543.42/.51
JSCS-2488
Original scientific paper
 

Studies of ferrocene derivatives. IV. Synthesis and NMR spectra of some (1-hydfroxy-w-alkenyl)-and (1-hydroxy-1-methil-w-alkenyl) ferrocenes 1,2

STANIMIR KONSTANTINOVIC, SVETLANA SIMOVA*  ZORAN RATKOVIC and JASMINA PREDOJEVIC

Department of Chemistry, Faculty of Science, University of Kragujevac, P.O. Box 60,
YU-34000 Kragujevac, Yugoslavia and
*Institute of Organic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

(Received 9 May 1997)
(1-Hydroxy-w-alkenyl)- and (1-hydroxy-1-methyl -w -alkenyl) ferrocenes have been synthesised and their high resolution 1H, and 13C-NMR spectra studied in view of the stereochemistry of a substituent connected to cyclopentadienyl ring. It is found that when these substituted ferrocene derivatives contain in the substituent a chiral center, the 2,3- and 3,4-positions in the cyclopentadienyl ring become pairwise diastereotopic and magnetically unequivalent.

Key words: (1-hydroxy-w-alkenyl)- and (1-hydroxy-methyl-w-alkenyl) ferrocenes, synthesis, NMR spectra 




J. Serb. Chem. Soc. 62(12) 1167-1174 (1997)
UDC 547.852.7:547.462.3:543.51
JSCS-2489
Original scientific paper
 

Stereochemistry of the cycloaddition reaction of 1-metyl-phthalazinium ylids to maleic and fumaric esters

STEFAN DIMA*, IONEL MANGALAGIU, MARIA CAPROSU and MAGDA PETROVANU

Al. I. Cuza University Iasi, Faculty of Chemistry, Organic Chemictry Department,
B-dul Copou, Nr.11, IASI-6600, Romania, and
*Dunarea de Jos University Galati, Faculty of Sciences, Chemistry Department,
Str. Domneasca, Nr.47, GALATI-6200, Romania

(Received 12 March, revised 12 August 1997)
For the first time in the phthalazinium ylids series we have a theoretical and experimental study concerning the stereochemistry of the 3+2 dipolar cycloaddition reaction of these ylids to symmetrically substituted cis-trans olefines. It has been proved that the cycloaddition reactions are mostly cis-stereospecific. A possible reaction mechanism is presented. Eight new pyrollophthalazine heterocycles have been obtained.

Key words: phthalazine, ylids, cycloaddition, stereochemistry. 




J. Serb. Chem. Soc. 62(12) 1175-1182 (1997)
UDC 547.854/.4
JSCS-2490
Original scientific paper

Reactivity of 3-N-(4-substituted phenyl)-5-carboxy uracils

N. V. VALENTIC, M. RADOJKOVIC-VELICKOVIC, M. MISIC-VUKOVIC and G. USCUMLIC

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4,
P.O.Box 494, YU-11001 Belgrade, Yugoslavia

(Received 27 July 1997)
The effect of various phenyl substituents on the reactivity of the carboxy groups of 3-N-(4-substituted phenyl)-5-carboxy uracils has been investigated. The substitutents at the phenyl nucleus were as follows: H, Br, I, NO2, OMe. The rate constants of the investigated acids in their reaction with diasodiphenylmethane (DDM) were determined in methanol and in ethanol at 30C, using the known spectrophotometric method. The obtained kinetic data, as well as the values of the IR stretching vibrations of the principals of linear free energy correlations. Considering that the substituted phenyl group resides at the nitrogen atom, having two carbonyl groups as ortho substituents, it is very probable that the effect of the substituents in position 4 of the phenyl nucleus is influenced by resonance interactions between the nitrogen electron pair, the carbonyl groups and the substituent itself. The polarity of the reaction medium also affects the complex resonance interactions in the molecules of the investigated compounds.

Key words: 3-N-(4-substituted phenyl)-5-carboxy uracils, diazodiphenylmethane, transmission of substituent effects, solvent effects.




J. Serb. Chem. Soc. 62(12) 1183-1186 (1997)
UDC 66.094.1/.18:656.762.2(546.98)
JSCS-2491
Original scientific paper

Hydriding and dehydriding of a graphite powder doped with palladium

MILENKO V. SUSIC

Serbian Academy of Sciences and Arts and the Faculty of Physical Chemistry,
University of Belgrade, Studentski trg 16, YU-11000 Belgrade, Yugoslavia

(Received 1 July 1997)
The hydriding and dehydriding process of a graphite powder doped with palladium was investigated. It was shown that, based on the spillover hydrogen effect the graphite powder is transformed into a very active hydrogen absorber. Kinetic and thermodynamic investigations of the hydriding and dehydriding processes have been conducted. The activation energy of the hydriding process and the enthalpies of the hydriding and dehydriding processes have been determined. The absorbed hydrogen and absorber (R) ratio has been determined and it has been shown that the prepared powder graphite acts as a very active hydrogen absorber.

Key words: Hydriding and dehydriding of graphite, spillover hydrogen effect. 




J. Serb. Chem. Soc. 62(12) 1187-1193 (1997)
UDC 547.497.1:546.73:541.428.79
JSCS-2492
Original scientific paper

The solvent dependence of the electron transfer reaction between the trans-dichlorobis (1,2-diaminoethane)cobalt(III) complex and hexacyanoferrate(II) in binary solvent mixtures

KUPPANAGOUNDER PITCHAIMUTHU ELANGO, KRISHNAMOORTHY ANBALAGAN*
and GOPALAKRISHNAN KARTHIKEYAN*

Department of Chemistry, Gandhigram Rural Institute, Gandhigram 624 302, Tamil Nadu, India

(Received 16 May, revised 12 August 1997)
The electron transfer reaction between trans-dichlorbis(1,2-diaminoethane)cobalt(III) ion and hexacyanoferrate(II), which proceeds via the formation of a precursor complex, has been investigated in aqueous mixtures of methanol, ethanol, tert-butanol and 1,4-dioxan. The association constant of the formation of the precursor complex and the rate constant for the electron transfer step have been experimentally determined in these binary solvent mixtures. The reaction was carried out at three different temperatures and the activation parameters have been computed. The effect of the solvent on the reaction rate has been analysed in the light of various solvent parameters.

Key words: cobalt(III), reduction, solvent effect, iron(II). 




J. Serb. Chem. Soc. 62(12) 1195-1200 (1997)
UDC 547.413.1:678.742:66.049
JSCS-2493
Original scientific paper
 

Phase separation in the ethylene-polyethylene system at high pressures. XII. Calculation of the solubility of ethylene in polyethylene using the PHC theory

VOJISLAV Z.BOGDANOVIC, ALEKSANDAR  Z. TASIC*, BOJAN D. DJORDJEVIC* and
ZAGORKA M. KOJIC

Hemijska industrija Pancevo, YU-26000 Pancevo and
*Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, P.O. Box 494, YU-11001 Belgrade, Yugoslavia

(Received 17 February, revised 24 July 1997)
The perturbed-hard-chain (PHC) theory was used to calculate the solubility values of ethylene in polyethylene at 403.15 K in the pressure range of  20-140 MPa, and the specific volumes of ethylene and polyethylene in the wide temperature and pressure ranges 375.15-471.15 K and 20-140 MPa, respectively. The procedure for these computation was presented in the preceding parts of the series of papers. The results obtained in the present work are in good agreement with other experimental and predicted values.

Key words: system ethylene polyethylene; PHC theory; specific volune; solubility of ethylene; high pressure. 




J. Serb. Chem. Soc. 62(12) 1201-1212 (1997)
UDC 541.124.7:537.6
JSCS-2494
Original scientific paper

Analysis of impedance data with dispersing effect by using the linear least squares regression method

HOUYI MA, SHENHAO CHEN, XIAOLIANG CHEN, XIAO CHEN, GUIQIU LI* and
XUDONG YANG*

Department of Chemistry, Shandong University and
*Department of Photo-Electronic Information Engineering, Shandong University Jinan, 250100, P.R. China

(Received 10 April 1997)
In the presence of the dispersing effect, the impedance of a double-layer behaves as a Constant Phase Element (CPE) rather than as an ideal capacitor. In this paper, the origin of the dispersing effect is satisfactorily accounted for by combining the CPE and the resistance element. The derived impedance expression for a single dispersing capacitive arc is consistent with the Cole-Cole formula. According to the manifestation of the dispersing effect in impedance (or admittance) complex planes, several linear relations have been proposed to calculate accurately and conveniently the electrochemical parameters from a single dispersing sapacitive loop using the linear least squares regression method. The method has also been applied to the analysis of inductive loops, as well as more complicated EIS.

Key words: dispersing effect, electrochemical impedance spectroscopy (EIS), constant phase element (CPE), double-layer, circuit description code (CDC). 




J. Serb. Chem. Soc. 62(12) 1213-1220 (1997)
UDC 546.193' 863'':543.257.1
JSCS-2495
Original scientific paper

Potntiometric and bipotentiometric determination of arsenic(III) and antimony(III) with dichromate in acidic solutions

VOJKA V. ANTONIJEVIC, SNEZANA D. NIKOLIC-MANDIC and TIBOR J.PASTOR
Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O.Boz 158, YU-11001 Belgrade Yugoslavia

(Received 4 April, revised 9 July 1997)
The influence of iodine, iodide, iodate and manganese(II), as well as the pretreatment of the platinum electrode, on the potentiometric determination of arsenic(III) and antimony(III) with dichromate in sulphuric and hydrochloric acid solutions, respectively, has been investigated. The bipotentiometric curves obtained during the determination of arsenic(III) with dichromate in 2.0-5.0 mol. dm-3 sulphuric acid solutions, indicate the presence of two reversible redox pairs in the solution. The redox systems As(V)/As(III) in 1.0-5.0 mol dm-3 hydrochloric acid solutions and Sb(V)/Sb(III) in 1.0-5.0 mol dm-3 sulphuric acid solutions are irreversible. Antimony(III) cannot be determined by the bipotentiometric method in hydrochloric acid solutions. A decrease in the polarization current of the indicator electrodes and an increase in the concentration of the acid lead to more pronounced potential difference changes at the end-point. Under optimal working conditions, the errors in the potentiometric and bipotentiometric determination of samples containing 15-40 mg of arsenic(III) or 25-60 mg of antimony(III) are not greater than 1.5%.

Key words: arsenic(III), antimony(III), dichromate, potentiometric and bipotentiometric titrations, induced reaction. 




J. Serb. Chem. Soc. 62(12) 1221-1225 (1997)
UDC 615.779:543.544
JSCS-2496
Original scientific paper

High performance liquid chromatographic determination of lincomycin in pharmaceutical formulations

SOTE VLADIMIROV, LJILJANA MARKOVIC*, DANICA AGBABA, DOBRILA ZIVANOV-STAKIC and JASMINA BRBORIC

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O.Box 146, Vojvode Stepe 450,
YU-11152 Belgrade and
*Department of Pharmacy, Vojvode Stepe 458, YU-11152 Belgrade, Yugoslavia

(Received 10 April 1997)
A specific and simple HPLC procedure has been developed, suitable for the determination of lincomycin hydrochloride monohydrate (LNHC) in pharmaceutical formations. Rp-HPLC analysis was performed with a LCD-Analytical Costa Metric 3000 system, equipped with Spectro Monitor 3100 UV/VIS detector. The lincomycin assay procedures were carried out on a Supelcosil LC-18-DB- (2504.6 mm, 5 m particles) column using an acetonitrile-postassium phosphate buffer (0,1; pH 2.50) (225:775 v/v) mobile phase. The column efluent was monitored at 208 nm for lincomycin. A calibration curve, in the concentration range from 200 to 1800 g ml-1 lincomycin, was established. The HPLC method was applied for the determination of lincomycin in pharmaceutical formulations, were satisfactory and ranged from 99.67% to 100.65% (R.S.D. ranged from 1.01% to 1.08%).

Key words: HPLC determination, lincomycin, pharmaceutical formulations. 




J. Serb. Chem. Soc. 62(12) 1227-1231 (1997)
UDC 615.777:547.673.6:543.242
JSCS-2497
Original scientific paper
Kinetic determination of Ti(III) in solution

RANKO M. SIMONOVIC, ALEKSANDAR R. IGOV* and RANGEL P. IGOV**

Faculty of Science, University of Pristina, YU-38000 Pristina,
*Ratko Pavlovic - NITEKS, Nis, YU-18000 Nis, and
Department of of Chemistry, Faculty of Philosophy, University of Nis, YU-18000 Nis, Yugoslavia

(Received 6 March, revised 24 June 1997)
A new reaction is suggested and a new kinetic method elaborated for the determination of Ti(III) traces in solution of the basis of their catalyzing effect on 4-hydroxycoumarin oxidation By KMnO4 in acetate buffer. The senisitivity of the method is 0.125 g cm-3. The probable relative error of the method is below 7.0 % and the method has relatively good selectivity.

Key words: Ti(III) determination, kinetic determination




J. Serb. Chem. Soc. 62(12) 1233-1237 (1997)
UDC 615.777:547.673.6:543.242
JSCS-2498
Original scientific paper
 

A kinetic method for the determination of the insecticide endosulfan

GORDANA A. MILOVANOVIC and LJILJANA TRIFKOVIC

Faculty of Chemistry, University of Belgrade, P.O.Box 158, YU-11001 Belgrade, Yugoslavia

(Received 10 April 1997)
A kinetic method for the determination of the insecticide endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathpiepin,3-oxide) is proposed. The activation effect of the insecticide on the oxidation of carminic acid by hydrogen peroxide catalyzed by copper(II) has been used. The reaction was carried out in an alkaline medium in a solution of acetone (0.17 mol dm-3) and dimethylformamide (0.13 mol dm-3), thus enabling the determination of endosulfan in the presence of the pesticides bifenox and isoproturon. The method enables the determination of endosulfan in the concentration range of 0.76-3.04 g cm-3 with a relative standard deviation of 2.7%. The effect of other pesticides on the accuracy of these determinations was investigated. In addition, a kinetic expression for the proposed indicator reaction was formulated, and the effect of temperature on the reaction rate was investigated. The correlative activation parameters were also calculated.

Key words: insecticide kinetic determination; endosulfan 6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano- 2,4,3-benzodioxathiepin, 3-oxide), oxidation of carminic acid; hydrogen peroxide. 




J. Serb. Chem. Soc. 62(12) 1239-1243 (1997)
UDC 543.866:542.97:66,094.3:547.673.6
JSCS-2499
Note

NOTE
Substrate inhibition of yeast alcohol dehydrogenase with comercial preparations of NAD+

S. TRIVIC, J. ZEREMSKI*, B. STANCIC**, and V.LESKOVAC***

Faculty of Science Novi Sad,
*Faculty of Technology and Metallurgy Belgrade,
**Faculty of Agriculture Novi Sad, and
*** Faculty of Technology Novi Sad, Yugoslavia

(Received 10 February, revised 24 June 1997)
A commercial preparation of NAD+ 95% from Sigma (Product No. N 0632) afforded substrate inhibition in the yeast alcohol dehydrogenase catalyzed oxidation of alcohols. A NAD+ 99% preparation from Sigma (Product No. N 1511) did not show any substrate inhibition under similar experimental conditions. It was concluded that the first preparation contained nucleotide impurities which caused substrate inhibition by NAD+.

Key words: yeast alcohol dehydrogenase, NAD+.



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