Chemistry Journal of Moldova. General, Industrial and Ecological Chemistry

8-25

Authors: Oxana Spinu, Igor Povar

The quantitative basis of the theory of buffer properties for two-phase acid-base buffer systems and for multicomponent heterogeneous systems has been derived. The analytical equations with respect to all components for diverse multicomponent systems were deduced. It has been established, that the buffer capacities of components are mutually proportional.

40-47

Authors: Masahiro Mikuriya, Mayu Hamagawa, Natsuki Tomioka, Daisuke Yoshioka, Naoko Uehara, Rika Fujimori, Hiroki Yamamoto, Yoshinari Ando, Shoichi Hori, Taro Kuriyama, Ryoji Mitsuhashi, Makoto Handa

Three kinds of copper(II) complexes with 1,4,7-tris(2-aminoethyl)-1,4,7-triazacyclononane (taetacn), [Cu(taetacn)](ClO4)2 (1), [Cu(Htaetacn)](ClO4)3 (2), and [Cu(Htaetacn)](BF4)3 (3) were synthesized and characterized by elemental analyses, IR and UV-Vis spectroscopies. The spectral features are in harmony with an octahedral geometry for 1 and a square-pyramidal coordination for 2 and 3.

54-57

Authors: Ion Dragalin, Olga Morarescu, Maria Sedcenco, Radu Marin Rosca

The accumulated as production waste fat from Faraon quail breeds has been investigated for the first time by using GC-MS technique, preventively converting it via methanolysis to fatty acid methyl esters. The test results, regarding the content of unsaturated fatty acids having a favorable to human body cis-configuration (77.8%), confirm their nutritional value and the possibility of using this fat in cosmetic, pharmaceutical and food industries.

62-67

Authors: Vsevolod Pogrebnoi

The reaction of (+)-D-glucose with 4-chloroaniline or 3,5-dibromoaniline leads almost exclusively to the β-configuration of glucosylated anilines. The acetylating of 2-(3,5-dibromophenylamino)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol is less selective than in case of the 2-(4-chlorophenylamino)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol.

77-88

Authors: Mohammad Taghi Taghizadeh, Morteza Vatanparast, Saeed Nasirianfar

Oxaziridine [c-CH3NO (X1A)], c-CH2NO (X2A) radicals and Cl, NH2 and methyl derivatives of oxaziridine structures have been optimized via DFTB3LYP level of theory using 6-311++G (d, p) basis set. Population analysis had been carried out. Vertical ionization energy (VIE) and adiabatic ionization energy (AIE), Fukui indices and some quantum chemical parameters were calculated. N-O bond was determined as weakest bond in oxaziridine triangle. The effect of electron withdrawing and electron donating groups on stability of weakest bond were assessed.

92-94

Authors: Irina Ginsari, Larisa Postolachi, Vasile Rusu, Oleg Petuhov, Tatiana Goreacioc, Tudor Lupascu, Raisa Nastas

Four series of samples containing manganese supported carbonaceous adsorbents were prepared. Obtained results reveal the importance of surface chemistry of carbonaceous adsorbents on the manganese loading.

9-19

Authors: Olga Morarescu

This review presents a synthetic transformations of ent-kaurane diterpenes, covering various aspects of the chemical and microbiologically transformations of native ent-kaur-16-en-19-oic acid, namely, its reactions via COOH groups, double bonds and rearrangements of the carbon skeleton, what we offer a wide range of natural and synthetic derivatives potentially biologically actives and convenient synthon for their synthesis.

25-32

Authors: Larisa Postolachi, Vasile Rusu, Tudor Lupascu, Alexei Maftuleac

The following factors which can improve the process of coagulation were studied: (i) the influence of stirring speed during coagulation and (ii) the influence of the concentration of the coagulant solution added in the process of coagulation. The coagulation process was studied on raw water of the Prut River. Application of the recommended procedure contribute to the reduction of the coagulant dose, the contact time, the aluminum concentration in water and the expenses for water treatment.

42-45

Authors: Ecaterina Covaci

The present work was undertaken to study the effect of the treatment temperature on the potassium bitartrate stability and composition of young wines. The thermodynamic parameters, namely ∆G°, ∆H°, ∆S° were calculated to predict the nature of potassium hydrogen tartrate (KHT) precipitation. According to the achieved results, the exothermal nature and thermodynamical feasibility of KHT precipitation in young wines were established. Based on thermodynamics, negative ∆G°, ∆H° values and positive ∆S° value give a spontaneous KHT process at lower temperatures.

52-56

Authors: Ana Lazarescu, Elena Melnic, Sergiu Shova, Victor Kravtsov, Constantin Turta

A lanthanum(III) cyanoacetate complex {[La2(CNCH2COO)6 (H2O)4]∙H2O}n (1) was synthesized and characterized by X-ray single-crystal analysis. The complex 1 exhibits one-dimensional coordination polymer structure. Cyanoacetate ligands coordinated in the bidentate bridging and tridentate-chelating bridging modes. The cyano-group of ligand is not coordinated to the lanthanide ion.

64-70

Authors: Natalia Sucman, Vsevolod Pogrebnoi, Mykola Obushak, Elena Melnic, Victor Kravtsov, Fliur Macaev

Described synthesis of 5-bromo substituted oxindoles linkages in spirocyclic butenolides exhibit relatively dependence of the structure-reactivity relationships of N-substituted isatines, dimethyl acetylenedicarboxylate and triphenylphoshine. The study of the stereochemistry of the atom C(2) of the spiro compounds was also unambiguously confirmed by single crystal X-ray analysis.

76-83

Authors: Tatiana Goreacioc

The surface chemistry of the commercial active carbon AG-5 has been modified by oxidation with concentrated nitric acid. The structural changes caused by oxidative treatment were estimated on the basis of nitrogen adsorption-desorption isotherms and thermal analysis. Boehm titration method and infrared spectral analysis have been used in order to evaluate surface chemistry characteristics of active carbon samples.

89-94

Authors: Mikhail Gorbachev, Natalia Gorinchoy, Ion Arsene

The preferred mechanism of the reaction of dihydroxyfumaric acid and its dimethyl ether with the free stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH*) was revealed by means of Density Functional Theory (DFT) calculations. The proposed mechanism has an ionic character and includes the formation of charge-transfer complexes as the main stage. It is also shown that the lower antioxidant activity of dimethyl ether of dihydroxyfumaric acid is caused by both its lower acidity (as compared with its precursor acid) and formation of more stable intermediates during its reaction with DPPH*. Our results allow one to rationalize the available experimental data.

104-112

Authors: Alexandru Gonta

After modification of enotannins, flavonols monomer units could be obtained with polyfunctional properties. Moreover, polyphenols are known to generate H2O2 and other ROS under alkaline conditions. ROS generation and catalytic influence of ferrous ions enhance the chemiluminescence light. Therefore in this work, Tox/Tris-Edta/Fe2+ ions have been used for screening luminescent properties of oxidized tannins.