J. Serb. Chem. Soc.
62(6) 451-454 (1997)
JSCS-2406
UDK
577.17:547.33/.94:547.466.1
Short
communication
SHORT COMMUNICATION
16-Dehydropregnenolone
acetate from solanidine
KATARINA T. M. PENOV-GASI, EVGENIJA A. DJURENDIC, DUSICA
RACKOV-COLIC, MARIJA N. SAKAC, OTTO N. ARCSON, LJUBICA MEDIC-MIJACEVIC* and
DUSAN MILJKOVIC
Institute of Chemistry, Faculty of Science, University of Novi
Sad,
Trg Dositeja Obradovica 3, YU 21 000 Novi
Sad and
*ICN Galenika - Institute, 29. Novembra
111, YU-11000 Belgrade, Yugoslavia
(Received
4 November 1996)
An elegant method for the chemical
transformation of solanidine to 16-dehydropregnonolone acetate is proposed.
Namely, solanidine was converted to 3b-acetoxy-5,20(22)-solanidiene
which was oxidized with sodium periodate-iodide system at pH 7-8 at room
temperature for 2 h. The obtained oxidation product, keto-lactame gave
16-dehydropregnenolone acetate after elimination of the lactamic part.
Key
words: solanidine, keto-lactame, 16-dehydropregnenolone acetate
J. Serb. Chem. Soc. 62(6) 455-458 (1997)
JSCS-2408
UDK 547.828.547.781.5
Original
scientific paper
A modified method for obtaining betahistine hydrochloride
KATARINA M. PENOV GASI, JULIJAN KANDRAC, OTTO N. ARCSON,
EVGENIJA A. CURENDIC, MARIJA N. SAKAC, VERA CIRIN-NOVTA and DUSAN MILJKOVIC
Institute of Chemistry, Faculty of Science, University of Novi
Sad, Trg Dositeja Obradovica 3, YU 21 000 Novi Sad, Yugoslavia
(Received
10 October 1996, revised 14 March 1997)
The aim of this work was to synthesize
betahistine hydrochloride of a satisfactory purity in the highest possible
yield. The synthesis consisted of four steps, condensation of paraformaldehyde
and 2-methylpyridine yielding 2-(2-pyridyl)ethanol (2) in a yield of at
least 26.6%, achieved thanks to a specially developed treatment of the reaction
mixture and recycling, dehydration of compound 2 with acetic anhydride
under reflyx, rendering 2-vinylpyridine (3) in a yield of 72%, addition
of methyl amine to the double bond of compound 3, giving betahistine (4)
in a yield of 62.5% and finally, preparation of betahistine hydrochloride from
betahistine and gaseous hydrochloride in absolute ethanol in a yield of 73%.
Key
words: betahistine hydrochloride, modified synthesis
J. Serb. Chem. Soc. 62(6) 459-471 (1997)
JSCS-2409
UDK 678.743:537.839.56
Original
scientific paper
Accelerator ion beam analysis of poly(vinyl chloride)
MAJA CVETKOVSKA, BARRY WILKENS* and JAMES MAYER*
St. Cyril and Methodias University, Faculty of Technology and
Metallurgy, Rudjer Boskovic 16,
91000 Skopje, Republic of Macedonia,
E-mail: Imad@ereb.mf.ukim.edu.mk and
*Arizona State University, Center for Solid
State Sciences, Tempe,
AZ 85287-1704 USA: E-mail:
Wilkens@csss.la.asu.edu
(Received
8 January 1997)
Poly(vinyl chlorida (PVC) has a wide
variety of applications and potential applications as a material for the
manufacture of medical devices and packaging films. In some fields of
application the demands are rigorous and so improvements in the analysis are
always of interest. In this work it is shown that Rutherford backscattering
spectrometry (RBS) and Forward recoil spectrometry (FRS) can be useful and
powerful analytical tools. that complement other methods, for the analysis of
PVC foils. By adjusting hr instrumental parameters to minimize he polymer
damage, it is possible to obtain the composition, the depth profile of heavy elements
in the polymer, and to investigate the segregation of some components to the
surfaces or interfaces. It is shown that at a fluence of 2.5x10-14 ions cm-2 (4He2+, 2MeV) it is possible
to obtain the correct composition of PVC (including additives, detectable by
RBS, in this case Si, with a concentrations of up to 1% w/w). At higher
irradiation doses elimination of chlorine and hydrogen atoms begins, but this
enables the recognition of elements which could not be identified previously because
of their very low concentration. For example, metals from metal salts added as
some type of stabilizer. The same effect enables the observation of segregation
to the surface of poly(dimethylsiloxane) block from triblock copolymer with
poly(caprolactone) present as an additive in PVC, by the appearance of an
increased concentration of Si at the surface. The segregation of Si at the
surface is proved also y SEM-EDX.
Key
words: Rutherfor backscattering spectrometry, Forward recoil spectrometry,
composition of PVC, segregation of Si at the surface of PVC foils
J. Serb. Chem. Soc. 62(6) 473-480 (1997)
JSCS-2410
UDK
678.774:536.4:542.9
Original
scientific paper
Phase transfer catalysis in polycondensation processes.
XVII. Synthesis and thermal properties of
some aromatic polyethers
N. HURDUC, M. GRIGORAS*, A. STOLERU* and NATALIA HURDUC**
Gh. Asachi Technical University - Department of Macromolecules,
Bd. Copou 11A, 6600 Iasi, Romania,
*P. Poni Institute of Macromolecular
Chemistry, Alee Gr. Ghica-Voda, 6600 Iasi, Romania and
**A. I. Cuza University, Physical Chemistry
Department, Bd. Copou 9, 6600 Iasi, Romania
(Received
2 March 1996)
This paper presents some aspects regarding
the synthesis and thermal properties of polyethers based on alpha a,a'-dibromo-p-xylene and various bisphenols. The polymers
were characterized by 1H-NMR, thermogravimetry, DSC and optical microscopy. To explain
some of the thermal behavior, theoretical conformational studies were performed
using a MMX program.
Key
words: phase transfer catalysis, aromatic polyethers, synthesis
J. Serb. Chem. Soc. 62(6) 481-494 (1997)
JSCS-2411
UDK
546.742:541.428.49:547.497.1
Original
scientific paper
Transition metal complexes with thiosemicarbazide-based ligands.
Part. 34. Synthesis, spectroscopic and
voltammetric characterization of Ni(II) and Ni(III) complexes with tetra-and
octadentate pentane-2,4-dione-bis(s-methylisothiosemicarbazone)-derived ligands
LJILJANA S. JOVANOVIC, VUKADIN M. LEOVAC, MIRJANA M. POPSAVIN,
VALERIJA I.CESLJEVIC, and LUKA BJELICA
Institute of Chemistry, Faculty of Science, University of Novi
Sad, Trg Dositeja Obradovica 3, YU 21 000 Novi Sad, Yugoslavia
(Received
25 November 1996, revised 15 March 1997)
The reaction of a methanolic or ethanolic
solution of [Ni(H2L)]I.9.5MeOH(1) (H2L=monoanion of the tetradentate N4 pentane-2,4-dione-bis(S-methylisothiosemicarbazone)
in the presence of ammonia yielded [Ni(HL)]MeOH(2), or Ni2(L-L)(3)(L-L =
hexaanion of the octadentate N8 3,4-diacetyl-2,5-hexanedione-tetrakis
(S-methylisothiosemicarbazone). The formation of complex (3) preceded an
oxidative dehydrogenation of the diketone C(3)-H group and a bonding of two
monomeric units of (1) into the dimer (3) via the single C(3)-H
group and a bonding of two monomeric units of (1) into the dimer (3) via
the single C(3)-C(3) bond, and the oxidation of Ni(II) to Ni(III). Complexes (1)
and (3) were characterized by their electronic, and complexes (1)
and (2) by their NMR spectra. The voltammetric behavior of all the
complexes in DMF solutions at a glassy carbon electrode was studied in detail.
Key
words: nickel(II) complexes, nickel(III) complexes,
S-methylisothiosemicarbazide-based ligands, NMR spectra, electronic spectra,
cyclic voltammetry
J. Serb. Chem. Soc. 62(6)495-502 (1997)
JSCS-2412
UDK
543.544.2/.5:530.18
Original
scientific paper
RM pair linearity and proportionality
rules in non-salting-out liquid chromatography
TOMISLAV JANJIC, GORDNA VUCKOVIC and MILENKO CELAP
Faculty of Chemistry, University of Belgrade, Akademski trg,
P.O.Box 158, YU-11001 Belgrade, Yugoslavia
(Received
16 December 1996)
It is shown that the RM pair linearity rule, as
well as the Proportionality rule, the validity of which in salting-out
chromatography was established earlier, are also often valid in other fields of
liquid chromatography.
Key
words: liquid chromatography, RM pair linearity rule, proportionality rule
J. Serb. Chem. Soc. 62(6) 503-508 (1997)
JSCS-2413
UDK
549.67:541.18.044/.045
Original
scientific paper
Investigation of the effect of novel hydrophobic zeolite types
on the pervaporation properties of composite polysiloxane membranes
BORIVOJ ADNACEVIC, JELENA JOVANOVIC* and SPASENKA GAJINOV*
Faculty of Physical Chemistry, University of Belgrade,
Studentski trg 12-16,
P.O.Box 137, YU-11001 Belgrade and
*Institute of General and Physical
Chemistry, Studentski trg 12/V,
P.O.Box 551, YU-11001 Belgrad, Yugoslavia
(Received
25 October 1996, revised 14 February 1997)
This paper describes investigations of the
effect of two different types of novel hydrophobic zeolites (ultrastable
zeolite type Y and pentasyl type zeolite) on the pervaporation properties of
zeolite-filled polydimethylsiloxane membranes. A procedure of obtaining
membranes of various thickness varying in the zeolite content was mastered.
Physicochemical characterization of the utilized zeolites was done. The effects
of the zeolite type and concentration, as well as the temperature and membrane
thickness on the membrane permeability and selectivity were established.
Key
words: hydrophobic zeolites, zeolites, zeolite-filled polydimethylsiloxane
membranes, pervaporation, permeability, selectivity
J. Serb. Chem. Soc. 62(6)509-514 (1997)
JSCS-2414
UDK
543.253:547.8.973:546.621/541.428.49/
Original
scientific paper
Polarographic study of eriochome cyanine R and its aluminum
complexes
DESANKA SUZNJEVIC, STEVAN BLAGOJEVIC, MILENKO ERCEG*, DRAGICA
DUMANOVIC** and DUSAN VUCELIC***
Institute of General and Physical Chemistry, Studentski trg
12/V,
P.O.Box 551, YU-11001 Belgrade,
*Forensic Institute, Kraljice Ane bb,
YU-11000 Belgrade,
**ICN Galenika - Institute, 29. Novembra
111, YU-11000 Belgrade and
***Faculty of Physical Chemistry,
University of Belgrade, Studentski trg 12-16,
P.O.Box 137, YU-11001 Belgrade, Yugoslavia
(Received
2 December 1996) The behavior of the two main cathodic polarographic waves of the
dye Eriochhrome cyanine R (ECR), A at -0.45V, and B at -0.1 vs. SCE, were
followed from acetate buffer pH 4.8 in the presence of Al3+ ions. Two new waves (E
and F) were noticed in the potential region between waves A and B. From
amperometric titrations, the mole ratios 1:1 and 2:3 of the formed Al-ERC
complexes, which correspond to the waves E and F, were determined. The
procedure for indirect analytical determination of aluminum was done by
monitoring the variation of the wave A height as a function of the Al3+ ion concentration. A
linear response of the wave height vs. the metal-ion of ±3% determined for the
aluminum ion concentration of 0.1 mg/l (n=10).
Key
words: eriocherome cyanine R, Al3+ complexes, polarography, mole ratio, determination
J. Serb. Chem. Soc. 62(6) 515-521 (1997)
JSCS-2415
UDK
661.634:541.183,546.923:541.573
Preliminary
communication
PRELIMINARY COMMUNICATION
The electrosorption valence of adsorbed
phosphoric acid anions on the Pt(111) surface
B. Z. NIKOLIC and R. R. ADZIC*
Faculty of Technology and Metallurgy, Karnegijeva 4, P.O.Box
494, YU-11001 Belgrade and
*ICTM - Institute of Electrochemistry,
Njegoseva 12, P.O.Box 815, YU-11001 Belgrade, Yugoslavia
(Received
16 January, revised 5 March 1997)
The adsorption of phosphoric acid anions on
the Pt(111) face has been studied using cyclic voltammetry. It is shown that
the adsorption of H3PO4 anions is stronger than that of H2SO4 or HClO4. From the voltammetry
curves obtained for the Pt(111) upon addition of H3PO4 solution with different
concentrations into 0.01 M HClO4 the electrosorption valence of H3PO4 on the Pt(111), g = -1 has been calculated. The voltammetric curves for Pt(111) in
concentrated H3PO4 and H2SO4 solutions show a sharp peak in the hydrogen region, which is
caused by anion adsorption and possibly by ordering of the adsorbed anions.
Key
words: electrosorption valence, adsorption, phosphoric acid, voltammetry
curve, Pt(111) face, charge
J. Serb. Chem. Soc. 62(6) 523-530 (1997)
JSCS-2416
UDK
546.47.815:622.765:543.51
Original
scientific paper
Precipitate flotation of lead and zinc and their determination
by atomic absorption spectrometry
KATARINA CUNDEVA and TRAJCE STAFILOV
Institute of Chemistry, Faculty of Science, St. Cyril and
Methodius University,
P.O.Box 162, 91001 Skopje, Macedonia
(Received
30 October 1996, revised 15 February 1997)
A preconcentration flotation procedure has
been developed to extend the range of conventional atomic absorption analysis
to trace concentration of lead and zinc in natural waters. The optimal
conditions for the preconcentration and separation of these metals from fresh
water by precipitate flotation with hydrated iron(III) oxide (Fe2O3xH2O) were studied. All
important parameters necessary for the successful flotation, like optimal mass
of collector, pH of the medium, induction time etc., were checked. Under the
same conditions Pb and Zn were floated quantitatively (100% for lead and 95.16%
for zinc) with 30 mg Fe(III). The possibility of the usage of atomic absorption
spectrometry was determined of the colligend levels in fresh water samples. The
quantitative determination of lead was carried out by electrothermal atomic
absorption spectrometry, while zinc was determined by flame atomic absorption
spectrometry. The results obtained by atomic absorption spectrometry were
compared with the results obtained by inductively coupled plasma-atomic
emission spectrometry. The detection limit for lead is 0.50 µg/L and for zinc
is 0.85 µg/L.
Key
words: lead, zinc, determination, precipitate flotation, atomic absorption
spectrometry
J. Serb. Chem. Soc. 62(6) 531-533 (1997)
JSCS-2417
UDK
633.88:66.066.1/:536.44
Note
NOTE
Dependence of the camomile flower yield on
the carbon dioxide quantity during isothermal supercritical extraction
BRANISLAV PEKIC, ZORAN ZEKOVIC and ALEKSANDAR TOLIC
Faculty of Technology, Department of Pharmaceutical Engineering,
University of Novi Sad,
Cara Lazara 1, YU-21000 Novi Sad,
Yugoslavia
(Received
2 July 1996, revised 27 January 1997)
The dependence of the total extract yield
of camomile flowers by isothermal supercritical extraction on the carbon
dioxide quantity, at different pressures (80, 160 and 240 bar) at a temperature
of 313 K, was investigated. A dynamic method was used. The experimentally
obtained results were described by equations which fitted the experimental
results rather well. The equations obtained in this way represent a
contribution to defining the quantitative dependence of yield on the carbon
dioxide quantity used in the extraction.
Key
words: camomile flowers, supercritical extraction, carbon dioxide