Chemistry Journal of Moldova. General, Industrial and Ecological Chemistry

6-9

Authors: T. L. Kalabegishvili, I. Murusidze, D. T. Pataraya, E. Ginturi, M. V. Frontasyeva, E. I. Kirkesali, Gh. Duca, I. Zinicovscaia

The increasing contamination of soil, sediment, and water with heavy metals by natural and industrial processes is a worldwide problem. Many bacteria and microalgae have demonstrated ability to absorb toxic elements. To study mercury biosorption by bacteria Arthrobacter globiformis and microalga Spirulina platensis neutron activation analysis (NAA) was applied. The process of mercury biosorption by these media was described by Freundlich and Langmuir-Freundlich Model. Both microorganisms showed a great potential to be used as biosorbing agents for mercury removal from the environment.

29-44

Authors: N. Secara, Gh. Duca, L. Vlad, F. Macaev

The paper summarizes literature data on occurrence of dihydroxyfumaric acid and its role in biological systems, as well as its chemical properties.

52-56

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

The polarographic catalytic current in acid solutions of Mo(VI), 2,3-dihydroxybenzaldehyde thiosemicarbazone (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 Ea = 15.9 kcal⋅mol-1 and the reaction activation entropy ΔSa ≠ = -23.5 e.u. have been calculated.

62-68

Authors: Gheorghe Nemţoi, Tudor Lupaşcu, Alexandra Ciomaga, Alexandru Cecal

This paper presents the results of scientifi c 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 voltammograms 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 identifi cation and determination of Enoxil in pharmaceuticals.

73-76

Authors: Valerian Cerempei

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 infl uence of butanol on the phase stability of ethanolgasoline mixtures was detected.

81-85

Authors: Elena Nezalzova

Quality control of alcoholic beverages, coming into the market, is a defi ning 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.

101-109

Authors: Oleg Radul, Natalia Sucman, Serghei Pogrebnoi, Alic Barba, Athina Geronikaki, Fliur Macaev

The synthesis and antiviral activity evaluation of new derivatives of 2-aminothiazole, 1,2,4-triazole, as well as oxindoles has been realized. The synthesized compounds exhibited different cytotoxicity, in particular, oxindols 4 , 5 , 7 , 8 , 9, 10, 11, 12, 13, 58 as well as thiazole/triazole 73 and 75 turned out to be the most cytotoxic for MT-4 cell lines. The compounds 11, 12, 73, and 75 are more toxic than reference compound Efavirenz. As far as the antiviral activity is concerned, none of the title compounds turned out active against Reo-1, Sb-1, VSV, RSV, YFV and VV viruses. The results obtained against Bovine Viral Diarrhoea Virus (BVDV) showed that nine compounds (six from oxindol’s seria 6, 12, 13, 52, 56, 58 and three 73, 75, 77 of triazole homologues) resulted moderate active. Among all of them, the most potent compound was 52, with EC50 of 6.6 μM. Studies of effect of synthesized compounds against Coxsakie Virus (CVB-2) revealed that only two compounds, 13 and 73 exhibit moderate activity (EC50 >40 and >18 μM, respectively). It should be noticed that eleven compounds, 4, 5, 7, 8, 9, 10, 11, 12, 13, 58, and 75 showed moderate activity against HIV-1 (EC50 >16 – m >59μM).

6-23

Authors: Liudmila Bets, Liudmila Vlad, Fliur Macaev

Carane-type compounds have attracted attention in recent years due to their practical importance. This review is focused on describing the developments in the synthesis of trimethylbicyclo[4.1.0]heptanes and their unsaturated analogues from monoterpenes (+)-2- and (+)-3-carenes published mostly during the last decade.

30-36

Authors: Angela Lis, Gheorghe Duca, Elena Bunduchi, Viorica Gladchi, Nelli Goreaceva

The Republic of Moldova is situated among countries with relatively poor water resources, therefore their protection and rational use remains a national problem. Due to its geographic position, the Republic of Moldova is subjected to transboundary pollution. The current work represents the estimation of the buffering capacity on the Dniester River waters and its tributaries between November 2008 and October 2009. Decrease of the buffering capacity in water basins leads to disruption of the normal activity of aquatic biota, by increasing the toxicity in their living environment. On the basis of the results of measurements, suggestions for the improvement of the situation will be made and for enhancing public awareness and public authorities involvement.

41-46

Authors: Duca Gh., Bogdevich O., Cadocinicov O., Porubin D.

The old pesticide storages in Moldova showed a large quantity of polluted sites. The inventory of POPs polluted sites showed a huge number of extra high polluted sites (more 50,0 mg/kg) which need the fi rst place a remediation or other action to eliminate direct contact with people and animals. The pollution spectrum of POPs is a complex and consists of fi ve groups: DDTs isomers, HCHs isomers, Toxaphene mixture, Chlordane and Heptachlor. The principal groups among these substances are DDTs and HCHs isomers.

54-58

Authors: Alexandra Marchenko, Pavel Kintia and Bożena Wyrzykiewicz

Four steroidal glycosides, named by us chamaedrosides, where two are new steroidal glycosides, have been isolated from the plants of Veronica chamaedrys L. (Scrophulariaceae) for the fi rst time and their structures have been elucidated. Complete assignments of the 1H and 13C NMR chemical shifts for these glycosides were achieved by means of one- and two-dimensional NMR techniques, including 1H-1H COSY, HSQC, HMBC and ROESY spectra.

68-72

Authors: Ion Dranca, Nicon Ungur, Tudor Lupascu, Oleg Petuhov

The methods of thermogravimetry (TGA) and differential scanning calorimetry (DSC) have been used to study the thermal and thermo-oxidative degradation of polystyrene (PS) and a PS-clay nanocompoiste. An advanced isoconversional method has been applied for kinetic analysis. Introduction of the clay phase increases the activation energy and affects the total heat of degradation, which suggests a change in the reaction mechanism. The obtained kinetic data permit a comparative assessment of fi re resistance of the studied materials.

83-87

Authors: Natalia Secara

The reaction of dihydroxyfumaric acid with the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied using the stopped-fl ow method, in order to describe the reaction kinetics. Dihydroxyfumaric acid reacts very rapidly with DPPH, the reaction being completed in several minutes. This 2-stoichiometric reaction proceeds in two stages, with reaction orders of 1 and 0.76 with respect to DPPH, and 0.5 and 0.3 with respect to DHF, respectively. The rate constant of the two stages of the reaction were found to be 39.1 (L/mol·s) and 0.0012 (s-1) at 20º C and pH 4.0.

7-23

Authors: Vasile Lozan

The coordination chemistry of dinickel macrocyclic hexaamine-dithiophenolate complexes of Robson-type with azoligands is presented in this microreview. All complexes have been characterised by IR-, UV/Vis-spectroscopy, and X-ray crystallography. The bioctahedral transition metal complexes of the type [(L6)Ni2(μ-L')]+ exhibit a rich coordination chemistry since the active coordination site L' is accessible for a wide range of exogenous coligands.

36-56

Authors: V. Sargorovschi, N. Sucman, T. Iudin, D. Duca, E. Stingaci, D. Prodius, S. Pogrebnoi, F. Macaev

Ionic liquids are becoming widely used in chemical processes. Taking this into account we focus on recent advances in the synthesis and the investigation of 1H-imidazole derived ionic liquids. The fi rst part of this paper focuses on describing the developments in the synthesis and physical properties of 1,3-disubstituted imidazolium salts. The second part describes the application of these unique reagents, as catalysts and solvents in organic chemistry.

73-77

Authors: Mihail Revenco, Mariana Martin, Waell Abu Dayyih

A potentiometric selective sensor based on trinuclear chromium(III) complex as a novel ionophore for the thiocyanate-selective electrode is reported. The sensor displays a near Nernstian slope of 57 ± 2 mV per decade, over a wide pH range 3 - 11. The working concentration range of the electrode is 1.10-5 – 1.10-1 mol/L with a detection limit of 5.10-6 mol/L. The sensor has a response time of 20 s and can be used for at least 6 months without any considerable fl uctuation of the potential. The selectivity coeffi cients determined at using the fi xed interference method indicate a good discriminating ability towards other anions. The prepared sensor was applied as an indicator electrode in the titration of thiocyanate with Ag+.

84-89

Authors: Maria Sandu, Elena Mosanu, Viorica Gladchi, A. Tarita, Gh. Duca, P. Spataru, T. Lupascu, E. Sergentu, Raisa Lozan, V. Jabin, S. Turcan

A spring is a component of the hydrosphere, where water fl ows on to the surface of the earth from below the surface. Thus it is where the aquifer surface meets the ground surface. It may be the result of karsts topography where surface water has infi ltrated the Earth’s surface, becoming part of the area groundwater. As sources of water supply in the Republic of Moldova underground waters constitute 15,2% (bore holes, springs and wells). The present work includes water quality investigations and aims to reveal local sources in river Nistru hydrographic basin (Rezina district) for drinking water provision in villages. Chemical composition of investigated spring’s water shows that in Rezina district 19% of springs are polluted with nitrogen compounds. Water of only 9% of springs is in conformity with the standard for drinking water. Water from 102 springs meets the requirements of irrigation that doesn’t present the risk of soil salinization (K > 18) – 1 383 L/min.

95-97

Authors: Aleksander G. Kasikov, Anna M. Petrova

The effect of sulphuric acid concentration on solvent extraction of ReO4 - by the long-chain aliphatic tertiary amines and alcohols in a wide range of H2SO4 concentrations in initial solutions is discussed. It has been established that the infl uence of the sulphuric acid concentration on rhenium solvent extraction is largely due to the extraction process mechanism. In the case of the anion-exchange mechanism, ReO4 - is best extracted from weakly acidic solutions, whereas when the hydrate-solvate mechanism takes place – from solutions containing 4-7 mole/l H2SO4.

106-109

Authors: Marina Grinco, Olga Chetraru, Veaceslav Kulciţki, Alic Barba, Alexandr Boico, Pavel F. Vlad and Nicon Ungur

The known diterpenic ester – 15α-angeloyl-ent-kaur-16-en-19-oic (angeloylgrandifl oric) acid has been isolated from the dry wastes of Helianthus annuus L. The synthesis of 15α-hydroxy- and 15-oxo-ent-kaur-16-en-19- oic acids starting from ent-kaur-16-en-19-oic acid has been performed.

118-120

Authors: Veaceslav Kulciţki, Marina Cara, Andrea Bourdelais, Tomas Schuster and Daniel Baden

This paper describes the use of a terpenic model substrate to conjugate 1,4-additions of N-bromosuccinimide (NBS) to a diene system possessing a suitable oxygen functionality. The reaction leads to functionalized tetrahydrofuran derivatives, which can be developed further into different synthetic targets, such as polyethers, which are known to possess diverse biological activity.

8-13

Authors: N.Ya. Tsibakhashvili, L. Mosulishvili, E. Kirkesali, T. Kalabegishvili, S. Kerkenjia, M.V. Frontasyeva, Gh. Duca, I. Zinicovscaia

Most powerful primary analytical technique, neutron activation analysis, was applied to study indigenous bacteria, namely, Arthrobacter genera which can be successfully used in detoxification and immobilization of toxic substances. In the present study the effect of Cr(VI) on the elemental content of these bacteria has been examined. The concentrations from 12 to 19 elements such as Na, Al, Cl, K, Fe, Co, Zn, As, Br, Rb, Sr, Sb, Ba, Tb, Th, U were determined in the bacterial cells. The high rate of Cr accumulation in the tested bacterial cells was shown. In bacteria treated with chromate some similarity in the behaviour of the following essential elements − potassium, sodium, chlorine − was observed. Such non-essential elements as Ag, As, Br and U were determined in all bacteria and have to be considered by cells as toxins.

24-27

Authors: Ludmila Kiriyak, Natalia Cecoi, Tatiana Cazac, Mihail Revenco

The polarographic behavior of the complex formed by V(V) and 2,3–dihydroxybenzaldehyde (2,3–DHBA) in the solution containing acetate buffer (pH 5,2) has been investigated. By means of a.c. polarography, chronovoltammetry and other techniques, it has been shown that the electrode process is complicated by the adsorption of 2,3-DHBA and its vanadium complex. The kinetic and adsorption parameters of the electrode process have been determined: adsorption equilibrium constant B= 1,32⋅105 mol-1⋅dm3, the attraction constant γ = 1,2, the maximum surface concentration Гmax = 9,10⋅10-11 mol⋅ cm-2; the share of the electrode surface occupied by one particle of the adsorbed complex S = 1,81 nm2 and the free adsorption energy ΔG = - 39,1 kJ· mol-1.

34-39

Authors: Olga Covaliova

The problem of preventing the heavy metals and other toxic substances release in environment due to the discharges of untreated plating and rinsing solutions is actual from both ecologic and economic point of view. It is crucial to prevent the environmental pollution and uncontrolled losses of resources (metals and other substances). The treatment technologies used today are not always efficient and cost saving and in some cases they may even provoke the secondary pollution of environment. Electrochemical treatment of industrial waste waters is one of the most promising technologies as it implies the same principles as the main technological processes and does not require introducing of chemicals into the treated solution. However, until now this method was given insufficient attention, although there are certain publications in this field [1]. The electrochemical behaviour of some d-metal complexes was studied and discussed from the viewpoint of water treatment requirements. The studies performed in the model plating solutions of Zn, Ni, Cu ammonia and pyrophosphate complexes, polynuclear Cr complexes have shown that the application of conventional reagent waste water treatment methods for such solutions would be inefficient. Examination of potentio-dynamic polarization curves registered in studied solutions have shown, that due to the formation of series of Zn ammonia complexes, alkaline treatment will not ensure Zn removal from such solutions, and application of electrocoagulation treatment method will not be efficient enough. It was also found that in case of Ni-, Crcontaining solutions electrochemical treatment can be used for Cu removal, whereas for the effective Cr(VI) removal the electrocoagulation would be required, which entails the redox processes resulted in the formation of hydroxides. The research has shown that the approach on the heavy metal removal from the used plating solutions may be different depending on the plating bath composition.

44-49

Authors: Boris Găină, Rodica Sturza, Violeta Bejan, Constantin Bodean

The basic objective of this work is studying the content of ochratoxin A (OTA) in grapes, grape juice, and wine. This is an analysis of their origin, the conditions of contamination and ways decontamination, toxiconogenes mushrooms, toxicity, world and European regulations. It was estimated the methods of detection of mycotoxins in wine products. It has examined the contents of OTA in the moldavian juice/wine from different varietals at different stages of winemaking and obtained by different proceeds winemaking.

60-67

Authors: Silvia Melnic, Denis Prodius, Sergiu Shova, Helen Stoeckli-Evans, Yurii Simonov, Alexander Feher, Maria Gdaniec, Constantin Turta

Nine new complexes with the general formula {[Ln2Ba(α-Fur)8(H2O)4]}n, where Ln = Nd3+, Sm3+, Eu3+, Pr3+, Gd3+, Tb3+, Ho3+, Er3+ and La3+; α-Fur ≡ C4H3OCOO, were synthesized and characterized by IR spectra, magnetism, X-ray single crystal and powder diffractions. The X-ray diffraction analysis reveals that all titled compounds are isostructural and possess 1D architecture with Ln ion in an eight-coordination geometry formed by six oxygen atoms from furoate and two oxygen atoms from water molecules. The magnetic behaviour of several synthesised complexes as well as {[Gd2Sr(α-Fur)8(H2O)4]}n was investigated in the temperature range of 1.8-300 K. The magnetic data were interpreted in the HDVV approximation with the exchange coupling constant J = - 0.014 cm- 1 that indicates antiferromagnetic interaction in {Gd2Sr}, whereas a ferromagnetic one J = + 0.007 cm-1 for {Gd2Ba}.

78-81

Authors: Oleg Radul, Alexandru Gudima, Fliur Macaev

New effective synthesis of the chiral chinchoninic acids form (-)-α-pinene has been elaborated. It has been shown that, the considerable increase of the yield and purity of chiral acids is achieved applying the method of under phase transfer catalysis.

86-93

Authors: Oleksandr Shkurenko, Kinga Suwinska, Florent Perret, Katia Sigaud, Antoine Leydier, Said Jebors and Anthony W. Coleman

Diamino-bicycloundecane mono-deprotonates H-calix[4]arene and the solid-structure of the resulting salt has been determined by X-ray crystallography. Two different complexes are present in the structure with the Diamino-bicycloundecane cation held in the calix[4]arene cavity by CH-p interactions. In the packing there is a hydrogen-bonded polymeric chain. Both the complexes formed layered structures with differing inter-layer distances.

100-104

Authors: Anca-Dana Bendrea, Ana-Maria Catargiu and Mircea Grigoras

Mesoporous SBA-15/conducting polymers composites, type SBA- polithiophene, SBA-polyaniline, respectively were synthesized and their physical properties were investigated. Polymers molecules were synthesized by chemical oxidative polymerization inside the pores of the mesoporous material by a post-synthesis process. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, thermal analysis and infrared spectroscopy.

116-117

Authors: Felix Shepel, Diana Shepel, Fliur Macaev

The increase of yield up to 63% of ethyl 5-hydroxy-1,2-dimethyl-1H-3-indolecarboxylate was obtained via the interaction of p-benzoquinone with N-methyl-β-aminocrotone ether in mixture of glacial acetic acid/ethyl acetate.

8-16

Authors: Tudor Lupascu, Pavel F. Vlad, Aculina Aricu, Maria Cocu

This communication deals with the appearance and development of the research in the fi eld of chemistry in the Republic of Moldova; at the beginning - in chemistry sections of Moldovan Branch of the USSR Academy of Sciences and then - at the Institute of Chemistry, founded in 1959. The dynamics of changes in the structure and research subjects is traced. Data are presented concerning the research results in the fi eld of the chemistry of coordination compounds, fi ne organic synthesis, natural products chemistry, physicochemical analysis, quantum chemistry, mineral resources, chemistry of natural water and purifi cation of waste water, the preparation and utilization of active carbons, and ecological chemistry. A detailed account both of basic research and applied investigation is given. The collaboration of our scientists with their colleagues from abroad is considered. Information is presented related to the scientifi c schools at our institute, its guidance and laboratory′s leaders. The scientifi c equipment of the institute is mentioned. The relationship of the institute with higher schools, as well as training of young researchers will be presented.

30-35

Authors: Pavel F. Vlad, Fliur Z. Macaev

This overview deals with the advances in the investigation in the fi eld of organic, bioorganic and natural products chemistry as well as the biologically active compounds in the Institute of Chemistry of the Academy of Sciences of Moldova.

44-55

Authors: Tudor Lupascu, Maria Gonta, Viorica Gladchi

This review details the most important achievements in the fi eld of ecological chemistry and environmental protection, obtained at the State University of Moldova and Institute of Chemistry of the Academy of Sciences of Moldova. The main research directions are described, as well as main scientifi c laboratories and centres of these two institutions.

66-71

Authors: Cristina Dinu, Gabriela Vasile, Liliana Cruceru, Jana Petre

The European Drinking Water Directive (98/83/EC), transposed in Romanian Legislation as Low 458/2002, amended by Low 311/2004, imposes the limit of concentration for metallic elements in water intended for human consumption. The toxic metals arsenic and selenium are among these elements and the limit value is 10 μg/L. In the paper there are presented the working conditions for determination of As and Se from drinking water using modern techniques based on the fl ow injection-hydride generation with the inductively coupled plasma atomic emission spectrometry (FIAS-ICP-EOS). The analyses were performed on Optima 5300 DV Perkin Elmer equipment with FIAS 400 Flow Injection System, Perkin Elmer type. For the hydride generation two types of solution were used: 10% (v/v) HCl as a carrier solution and 0.2 % NaBH4 in 0.05%NaOH solution as a reducing agent [1]. The treatment step of the samples and standard solutions consisted in reducing with mixed solutions of KI and ascorbic acid in acidic condition (HCl) for As and only with HCl and high temperature for Se [2,3]. The paper contains the characteristic parameters of the methods, such as: low detection limit, quantifi cation limit, repeatability, precision, recovery, which were evaluated using Certifi ed Reference Materials for each element.

75-78

Authors: Vasile Rusu and Aliona Vrinceanu

Studies of the sorption capacity towards Cu2+ ions of diatomite from the Ghidirim location of RM, as well as of the extracted clay phase are presented. Separated clay fraction from diatomic material is clean enough, and especially is rich in montmorillonite. Maximum sorption capacity for studied clay fraction is achieved by rising the temperature of calcination treatment up to 200oC. At higher temperatures the lattice of montmorillonite is contracted and its sorption capacity towards Cu2+ ions decreases strongly.

84-89

Authors: E.N. Kornilova, N.I.Kornilov, O.N Vasiltseva

Mineral waters of Russia, the CIS countries (Ukraine, Belarus, Moldova, Armenia, Azerbaijan, Georgia and Uzbekistan) and EU (Germany, France, Italy, Spain and some East European countries) carried to Chloride- Hydrocarbonate type have been investigated in this work. The analytical dependences connecting, entered by authors, characteristic parameters of structure of waters (

97-102

Authors: Loredana Vacareanu (Stafie), Virgil Barboiu, Daniel Timpu, Mircea Grigoras

A Schiff base macrocycle with persistent rhomboidal shape was synthesized in excellent yield through [2+2] condensation reaction between (R,R)-1,2-diaminocyclohexane and 4,4’-diformyltriphenylamine. The dimeric macrocylic structure was proved by electrospray ionization mass spectrometry (ESI-MS), 1H-NMR, and FTIR spectroscopy. The complexation properties were evidenced by UV absorption.

111-117

Authors: O. I. Gona, N. V. Stolyarchuk, Yu. L. Zub, and N. A. Yaroshenko

Mesoporous silicas with the thiourea functional group ≡Si(CH2)3NHC(S)NHC2H5 have been synthesized by monotemplate and bitemplate route (bitemplate is cetylpyridinium chloride as micelle-forming surfactant and monoethanolamide of saturated n-aliphatic acid as non-micelle-forming surfactant). The infl uence of a number of factors on mesoporous silicas structure has been studied: alkoxysilanes and surfactants concentration, and as well as the nature of medium in hydrothermal treatment of mesophases. The optimum conditions under which functionalized mesoporous silicas have possessing highly ordered hexagonal structure have been found. The surface area of mesoporous silicas synthesized using optimum bitemplate solubilization composition reaches 1055-1350 m2/g and sorption volume and pore diameter are 0.75-0.95 cm3/g and 2.5-2.9 nm respectively.

123-128

Authors: N. N. Gorinchoy, B. Dobrova, M. Yu. Gorbachev, G. Munteanu and I. Ya. Ogurtsov

The present work is devoted to the theoretical study of the activation of the acetylene molecule coordinated in the [Pt(PPh3)2C2H2] complex. By means of DFT calculations it is shown that the geometrical and electronic characteristics of the C2H2 are essentially changed due to its coordination. The subsequent detailed analysis of the molecular orbitals (MO) of the active valence zone of this complex allows one to make important conclusion that this activation is being realized mainly due to the orbital back donation of 5d-electronic density from one of the occupied MOs of the complex [Pt(PPh3)2] to the unoccupied antibonding π*-MO of C2H2.