Chemistry Journal of Moldova. General, Industrial and Ecological Chemistry

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.