JSCS Vol 64, No. 11
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J. Serb. Chem. Soc. 64(11) 647-654 (1999)
UDC 547.567:66.094.1:543.867-PP
JSCS-2703
Original scientific paper
The kinetics of the reduction of the
lipophilic quinone avarone by n-alkyl-1,4-dihydronicotinamides of
various lipophilicities
MARIO ZLATOVIC, DUSAN SLADIC and MIROSLAV J. GASIC
Faculty of Chemistry and Center for
Chemistry, ICTM, University of Belgrade, Studentski trg 14, Belgrade, Yugoslavia
(Received 16 March 1999)
Several NADH model compounds, N-alkyl-1,4-dihydronicotinamides,
some of them possessing amphiphilic properties, have been synthesized, and the
kinetics of their reaction with a biologically active liphophilic quinone, avarone,
has been studied in a protic solvent both in the presence and absence of
cationic, anionic or non-ionic surfactants. In the absence of micellar agents,
the medium- and long-chain N-dodecyl (3) and N-heptadecyl
(4) derivatives show a significant increase in the reaction rates
compared to other model compounds, due to the stabilization of the semiquinone
intermediate. Anionic surfactants retard the reaction, non-ionic surfactants
slightly accelerate the reaction with the short-chain derivatives, and retard
the reaction with the medium- and long-chain derivatives, and the cationic
surfactants increase the reaction rate with all derivatives except the
long-chain 4. The results support the e-p-e mechanism of the reduction
of lipophilic quinones by NADH models in protic medium.
Key words: avarone, quinone, NADH models,
surfactants, kinetics.
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J. Serb. Chem. Soc. 64(11) 655-662 (1999)
UDC 547.772/547.853.3:542.9
JSCS-2704
Original scientific paper
Synthesis of some pyrazolo[3,4-d]pyrimidines
and their fused triazole and tetrazole derivatives
SAMIRA A. SWELAM, OSAMA I. ABD EL-SALAM and MAGDI E. A. ZAKI
National Research Centre, Dokki,
Cairo-12622, Egypt
(Received 26 February
1999)
Reaction of 2 with different reagents, namely
formic acid, acetic anhydride and trichloroacetonitrile, yielded pyrazolo[3,4-d]pyrimidine
derivatives 3, 5 and 6, respectively. Pyrazolo[3,4-d]pyrimidine
m-thiazine(7) and 2,4-(1H,3H)dithione (8) derivatives were formed
by the action of carbon disulfide on 2, depending on the reaction
medium. Interaction of 7 with hydrazine hydrate yielded the aminoimino
derivative 9 which reacted with acetic anhydride, triethyl orthoacetate
and/or appropriate aldehydes to give 11, 12 and 13a,b,
respectively. Methylation of compound 8 gave 14, which reacted
with hydrazine hydrate to afford the monohydrazino derivative 15.
Reaction of 15, with formic acid and nitrous acid afforded pyrazolo[4,3-e]triazolo[1,5-c]pyrimidine
(16) and pyrazolo[4,3-e]tetrazolo-[1,5-c]pyrimidine (17)
derivatives, respectively. The structures of products 3-17 were
identified in light of their elemental analyses and spectra data.
Key words: pyrazolo[3,4-d]pyrimidine,
m-thiazine, rearragnement, triazolo[1,5-c]-pyrimidine,
tetrazolo[1,5-c]pyrimidine.
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J. Serb. Chem. Soc. 64(11) 663-672 (1999)
UDC 547.852.7/.9:542.9
JSCS-2705
Original scientific paper
Synthesis and reactions of 4-(p-methoxybenzyl)-6-[5,6,7,8-tetrahydro-2-naphthyl]-pyridazin-3(2H)-one
NAGWA M.S. EL-DIN HARB
Chemistry Department, Faculty of
Science, Ain Shams University, Abbasia, Cairo, Egypt
(Received 25 December
1998, revised 2 June 1999)
The condensation of 4-(p-methoxybenzyl)-6-[5,6,7,8-tetrahydro-2-naphthyl]-pyridazin-3(2H)-one
(3), prepared by the reaction of
6-[5,6,7,8-tetrahydro-2-naphthyl]-4,5-dihydropyridazin-3(2H)-one (1)
and anisaldehyde, with dimethyl sulphate, formaldehyde and acrylonitrile, and
also the formation of the Mannich base, proceeded smoothly at the 2-position to
give compounds 4,5,6,7, respectively. 4-p-Methoxybenzyl-3-chloro-6-[5,6,7,8-tetrahydro-2-naphthyl]-pyridazine
(9) was prepared in law yield by the action of phosphorus oxychloride on
3. The reaction of 9 with benzylamine, aniline and piperidine
gave 10a,b,c, respectively. 4-p-Methoxybenzyl-6-[5,6,7,8-tetrahydro-2-napthyl]pyridazine-3(2H)-thione
(12) was prepared either by the action of thiourea on 9, or by
the reaction of 3 with phosphorus pentasulphide. The reaction of these
thiones with acrylonitrile, morpholine and piperidine to give 13 and 14
a,b, respectively, were also investigated.
Key words: pyridazin-3(2H)-one, dimethyl
sulphate, formaldehyde, acrylonitrile, chloropyridazine, benzylamine, aniline,
piperidine, pyridazinthione, morpholine.
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J.
Serb. Chem. Soc. 64(11) 673-680 (1999)
UDC 547.313:543.42/.51:539.27
JSCS-2706
Original scientific
paper
The high-energy band in the
photoelectron spectrum of alkanes and its dependence on molecular structure
IVAN GUTMAN, VIKTORIJA GINEITYTE*, MIRKO LEPOVIC and MIROSLAV
PETROVIC
Faculty of Science, University, of
Kragujevac, P.O.Box 60, YU-34000 Kragujevac, Yugoslavia, and
*Institute of Theoretical Physics and Astronomy, Gostauto 12, 2600
Vilnius, Lithuania
(Recived 20 May 1999)
In the model for the ionization energies of the
C2s-electrons in saturated hydrocarbons, put
forward by Heilbronner et al., the energy levels are calculated as eigenvalues
of the line graph of the hydrogen-filled molecular graph. It is now shown that
in the case of alkanes, these energy levels are related to the Laplacian
eigenvalues of the molecular graph. A few rules are formulated, relating these
ionization energies with molecular structure.
Key words: photoelectron spectrum (of
alkanes), ionization energy, molecular graph, Laplacian eigenvalues.
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J.
Serb. Chem. Soc. 64(11) 681-684 (1999)
UDC 535.56:661.784.7
JSCS-2707
Note
N O T E
A
note on the Noyori model for chiral amplification in the aminoalcohol-catalyzed
reaction of aldehydes with dialkylzinc
IVAN GUTMAN
Faculty of Science, University of
Kragujevac, P.O.Box 60, YU-34000 Kragujevac, Yugoslavia
(Received 18 June 1999)
The Noyori model of chiral amplification in the
alkylation of aldehydes by means of dialkylzinc, catalyzed by chiral
aminoalcohols, is further elaborated. A direct, but approximate, relation is
obtained between the enantiomeric excess of the catalyst added and the
enantiomeric excess of the product.
Key words: chiral stereoselection, chiral
amplification, chiral catalysis, asymmetric synthesis.
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J.
Serb. Chem. Soc. 64(11 )685-693 (1999)
UDC 546.621:541.138.2548.736.372:620.179.6
JSCS-2708
Original scientific paper
Real surface area of the aluminium
electrode in sodium chloride solution
D. M. DRAZIC, J. P. POPIC and Z. RAKOCEVIC*
Institute of Electrochemistry ICTM,
Njegoseva 12, P.O.Box 815, YU-11001 Belgrade, and
*Vinca Institute of Nuclear Sciences, P.O.Box 522, YU-11001
Belgrade, Yugoslavia
(Received 10 July 1999)
By combining the techniques of electrochemical
slow potentiodynamic, AC impedance and atomic force microscopy (AFM), it was
shown that the differences in the anodic dissolution rates of Al in 0.5 NaCl
solutions as measured experimentally in the potential region between the
corrosion and pitting potential, are mainly due to differences in surface
roughness of the electrodes used. It was shown that mechanical grinding and
polishing of the electrode surface with emery paper (400 grit) and alumina
polishing powder (f 0.25 mm) can produce surfaces differing by a factor of 6 in
the roughness factor Ra. By using AFM estimates of the roughness factors
a true electrode capacitance of 4.63 µC cm-2 and thickness dox ~ 2.0 nm for the barrier layer of the surface film was estamited.
The outer part of the film is porous, partly as amorphous Al(OH)3, or crystalline bayerite (Al2O3.3H2O).
Key words: aluminium, corrosion, real surface
area, oxide thickness.
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J.
Serb. Chem. Soc. 64(11) 695-705 (1999)
UDC 546.92:548.55:541.138.3:546.185-325
JSCS-2709
Original scientific paper
Oxygen reduction on single crystal
platinum electrodes in phosphoric acid solutions
A. TANAKA, R. ADZIC* and B.
NIKOLIC**
University of Sao Paulo, Caixa
Postal 780-CEP 13560-970, Sao Carlos, Brasil,
*ICTM-Center for Electrochemistry and Center for Multidisciplinary
Studies, University of Belgrade, Belgrade, Yugoslavia and
**Faculty of Technology and Metallurgy, University of Belgrade,
P.O.Box 3503, YU-11120 Belgrade, Yugoslavia
(Received 18 June 1999)
Oxygen reduction reaction has been studied on Pt
low index planes in 0.1 M and 85% H3PO4 using hanging meniscus rotating disc electrode technique. The
first-order kinetics of O2 reduction reaction was found for all three
surfaces in a four-electron process with the first electron transfer rate
determining in both 0.1 M and 85% H2PO4 solutions. Catalytic activity for O2 reduction follows the sequence Pt (110)>>Pt (100)>>Pt
(111). Structural dependence is predominantly determined by the adsorption of
phosphoric acid anions, which is strongly structure-dependent on Pt surfaces.
Key words: oxygen reduction, Pt low-index
single crystal, H3PO4, hanging meniscus rotating disc electrode,
current-potential curves, Tafel plots.
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J.
Serb. Chem. Soc. 64(11) 707-720 (1999)
UDC 669.65:546.47' 48'':543.5
JSCS-2710
Original scientific paper
Determination of the zinc and cadmium contents
in low-alloyed tin
N. Z. BLAGOJEVIC, R. M. ZEJNILOVIC, A. R. DESPIC* and Z. BLECIC
Faculty of Metallurgy and
Technology, University of Montenegro, Cetinjski put b.b., YU-81000 Podgorica
and
*Institute of Technical Sciences SASA, P.O. Box 745, YU-11001
Belgrade, Yugoslavia
(Received 28 April 1999)
The method of anodic linear sweep voltammetry
(ALSV) has been used to determine the content of Zn and Cd (up to 4% w/w) in
eutectic type binary alloys with Sn. The alloy samples were prepared by
casting. The effect of the type and the pH of the electrolyte, as well as of
the sweep-rate on the dissolution of Zn and Cd from the alloy during an anodic
potentinal-sweep was investigated. It was shown that ALSV is sensitive to low
concentrations of both Zn and Cd in the investigated alloys, as well-defined
peaks of the dissolution of the two metals were recorded before the massive
dissolution of Sn commenced. Well-defined linear dependencies between the
quantities of electricity under the dissolution peaks of Zn (QZn) or Cd (QCd)
and the respective contents of the metals in the alloys were found. Intercepts
at the abscissa were found in both investigated systems indicating the
formation of solid solutions from which neither Zn nor Cd could be eluted. In
both alloys, the smallest amount of the alloying component which could be
detected was 0.25% (w/w). The application of the ALSV method has several
advantages over other analytical methods: it is non-destructive as the dissolution
involves only a very thin layer of the alloy; it requires simple and cheap
instrumentation; it is fast and relatively sensitive. These make it suitable
for routine analysis.
Key words: anodic linear potential sweep;
Sn-Zn alloy; Sn-Cd alloy; analytical determination of Zn and Cd
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Copyright & copy; SHD 1999.
Last
Updated December 7, 1999
For
more information contact: SHD@elab.tmf.bg.ac.yu