Research paper

SYNTHESIS AND CHARACTERIZATION OF [(5-MERCAPTO-1,3,4-OXADIAZOL-2-YL)ARYL]-3,5-DIARYL-4,5-DIHYDRO-1H-PYRAZOLE-1-CARBOTHIOAMIDES

Author(s):

Zinaida Ribkovskaia, Serghei Pogrebnoi, Alic Barba, Fliur Macaev

Field: Organic chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 90-100

Keywords: carbothioamides, pyrazolines, isothiocyanatophenyl-2-thio-1,3,4-oxadiazoles.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).04

Graphical Abstract:

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SYNTHESIS AND IR, NMR CARACTERISATION OF NEW P-(N,N-DIPHENYLAMINO) CHALCONES

Author(s):

Sîrbu Dumitru, Marin Ion

Field: Organic chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 86-89

Keywords: chalcone, isothiocyanat, imidazole, NMR, IR.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).05

Graphical Abstract: This article reports on the high yield synthesis and novel chalcones with isothiocyanate and imidazol groups. The synthesis was started from N,N-diphenilamine and finished with 4-(N,N-diphenylamino)-4’-(2-thioxo-imidazolidin-4-one)-chalcone, where the cheap and accessible reagents were used.

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HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY FOR DETERMINATION OF AROMATIC ALDEHYDES IN WINE DISTILLATES

Author(s):

Elena Nezalzova

Field: Food chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 81-85

Keywords: wine distillate, age of maturation, aromatic aldehydes, high-performance liquid chromatography.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).06

Graphical Abstract: Quality control of alcoholic beverages, coming into the market, is a defining element in preventing the production and supplying of defective products. One of the main criteria for quality control of wine distillates is to estimate their age, and more precisely the period of maturation as the dominant factor in determining the quality of cognacs and, consequently, their market price. On the opinion of majority scientists, one of the main factors, which determines the age of wine distillates, is the content of aromatic aldehydes, mostly vanillin, and their ratio.

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PRODUCTS DERIVED FROM CATALYTIC OXIDATION OF METHYLENE BLUE

Author(s):

T. Lupaşcu, M. Ciobanu, O. Bogdevici, V. Boţan

Field: Ecological chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 77-80

Keywords: methylene blue, catalytic oxidation, chromatography, mass spectrometry.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).07

Graphical Abstract: It was established that the process of catalytic oxidation of methylene blue, at low concentrations (20 mg/L), i.e. in real solutions, gives sulfates and nitrates and new product, which can be categorized, in their vast majority, as impurities, probably got from the vacuum distillation unit, which make up for only ~ 10 % of methylene blue used in the experiment. Methylene blue adsorption at the interface occurs in real solutions. In case of performing the process at methylene blue concentration of 120 mg/L, hemi-micelles are adsorbed at the interface and the OH• radical acts more effectively due to the presence at the interface of a greater number of dye molecules.

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PHASE STABILITY OF MONOATOMIC ALCOHOL-GASOLINE MIXTURES FOR DIFFERENT COMPOSITIONS AND HYDRODYNAMIC CONDITIONS

Author(s):

Valerian Cerempei

Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 73-76

Keywords: butanol, ethanol, gasoline, mixtures, phase stability.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).08

Graphical Abstract: The article investigates phase stability for the mixtures of monoatomic alcohols (ethanol, butanol) with gasoline in the presence of water. There have been determined the optimal storage conditions of mixtures depending on their composition and mixing conditions. The positive influence of butanol on the phase stability of ethanol-gasoline mixtures was detected.

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VOLTAMMETRIC CHARACTERIZATION OF THE BEHAVIOR OF BIOLOGICALLY ACTIVE COMPOUND ENOXIL IN VARIOUS MEDIA

Author(s):

Gheorghe Nemţoi, Tudor Lupaşcu, Alexandra Ciomaga, Alexandru Cecal

Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 62-68

Keywords: complex biologically active compound Enoxil, cyclic voltammetry, standard redox potential, dosage of pharmaceuticals.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).09

Graphical Abstract: This paper presents the results of scientific research related to the electrochemical behavior of the complex preparation Enoxil. It was established that the oxidation-reduction process of Enoxil is quasireversible. The reactivity of Enoxil obtained from alcohol soluble enotannins is more pronounced, compared to that obtained from standard enotannins. The dependence of cathodic current intensity on Enoxil concentration is linear. This can be used to establish Enoxil concentration in solution. Cyclic voltamograms were used to establish reduction and oxidation potential and the formal redox potential on platinum electrode in sodium perchlorate aqueous environment. These features can be used for identification and determination of Enoxil in pharmaceuticals.

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TEMPERATURE INFLUENCE ON PHASE STABILITY OF ETHANOL-GASOLINE MIXTURES

Author(s):

Valerian Cerempei

Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 69-72

Keywords: composition, ethanol, gasoline, mixtures, phase stability, temperature.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).10

Graphical Abstract: The article investigates phase stability of ethanol-gasoline mixtures depending on their composition, water concentration in ethanol and ethanol-gasoline mixture and temperature. There have been determined the perfect functioning conditions of spark ignition engines fueled with ethanol-gasoline mixtures.

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TO THE EQUILIBRIUM MODEL CHOICE IN HETEROGENEOUS AQUEOUS SYSTEMS. 1. THEORETICAL BASIS IN THE CASE OF TWO COEXISTING SOLID PHASES

Author(s):

I. Povar, Nina Timbaliuc, Tatiana Cazac, Diana Shepel, Oxana Spinu and Ludmila Chiriac

Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 57-61

Keywords: equilibrium model, heterogeneous system, solubility product, pH value, solid phase.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).11

Graphical Abstract: An approach has been developed to determine the equilibrium model in heterogeneous aqueous systems containing a mixture of solid phases from the initial composition of the heterogeneous mixture and the equilibrium values of the pH. This approach allows to significantly reduce the quantity of measured data, properly for solubility measurements. By using the new deduced equations it is possible to determine the solubility products of precipitates on the basis of the known composition of initial mixtures and pH values of saturated solutions avoiding some difficult experimental solubility measurements. The derived relations are useful for solving both direct and indirect equilibrium problems.

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THE INFLUENCE OF THIOSEMICARBAZONE 2,3-DIHYDROXYBENZALDEHYDE ON CATALYTIC CURRENTS IN THE SYSTEM MOLYBDENUM (VI) – POTASSIUM CHLORATE IN ACID SULFATE SOLUTIONS

Author(s):

Ludmila Chiriac, Tatiana Cazac, I. Povar and M. Revenco

Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 52-56

Keywords: voltammetry, catalytic current, molybdenum, thiosemicarbazone 2,3-dihydroxybenzaldehyde, chlorate of potassium.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).12

Graphical Abstract: The polarographic catalytic current in acid solutions of Mo(VI), thiosemicarbazone 2,3-dihydroxybenzaldehyde (TSC 2,3-DHBA) and chlorate ions has been investigated. The scheme of reactions, taking place in the solutions and on the electrode, has been proposed. The increase of the catalytic current is explained by the formation of an active intermediate complex [Mo(V)×TSC 2,3-DHBA (ClO^-₃)]. The rate constant of this complex formation K = 2.56 × 10⁶ mol^-1×dm³×s^-1, the activation energy E_a= 15.9 kcal×mol^-1 and the reaction activation entropy ∆S_a^¹ = -23.5 e.u. have been calculated.

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VOLTAMMETRIC BEHAVIOR OF SOME STEELS IN AQUEOUS SOLUTIONS OF HNO3

Author(s):

Gheorghe Nemtoi, Liliana Airinei, Tudor Lupascu and Alexandru Cecal

Field: Analytical chemistry
Type: Research paper
Issue: 2011 Volume 6, no.1
Pages: 45-51

Keywords: corrosion, electrochemical parameters, nitric acid, steels, voltammograms.
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Abstract (JPEG)

DOI: dx.doi.org/10.19261/cjm.2011.06(1).13

Graphical Abstract: The corrosion process of some steels immersed in HNO₃ solutions of different concentrations by means of voltammetric measurements was investigated. For different values of the corrosion potential, or of the contact time: solid steel-aggressive medium, several equations of the type: I = f (E) were proposed, only for linear domains of the voltammograms.

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