Chemistry Journal of Moldova

DOI: http://dx.doi.org/10.19261/cjm.2018.522   

Abstract (PDF) 

Graphical Abstract: The present work provides an insight into the effect of the nature of surfactant (cationic, anionic), a component of water- and oil-borne microemulsions, on the reaction rate of 1,3-dipolar cycloaddition of C,N-diphenylnitrone with acrylonitrile. The electrostatically attractive character of the cationic surfactant, would bring the reactants closer to each other; hence, a rate enhancement would ensue, particularly within the water-rich zone. Besides the fact that acrylonitrile played a dual role, as a component of the microemulsion and a dipolarphile in the cycloaddition reaction, made the work-up advantageously sound. Additionally, the increase in reagents molar ratio was found to promote higher reactivity.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.516   

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Graphical Abstract: The article presents the results of studies regarding the improvement of the qualitative characteristics of blast furnace coke obtained from modified coal blend in industrial conditions of Avdeevka Coke Plant. Inorganic corundum powders are applied to modify the coal blend, namely electrocorundum (α-Al2O3) and carborundum (α-SiC). The introduction of a specific quantity (0.25 wt %) of non-clinkering additives allows the modification of the processes that occur when the coal blend is plastic, with consequent improvement in coke strength.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.514 

Abstract (PDF)

Graphical Abstract: The chemical composition of industrially obtained Levisticum officinale W.D.J. Koch (lovage) essential oil of Moldovan origin was analysed by means of chromatographic (GC-MS) and spectral (IR, 1H and 13C NMR) methods. The obtained results show that the main components of L. officinale essential oil are monoterpenic hydrocarbons which make up to 53.50% of the total number of components. L. officinale essential oil is also characterized by a high content of oxygenated monoterpenes (alcohols, cetones and esters), which reaches up to 33.60%. For the first time the presence of 6-butyl-cyclohepta-1,4-diene (0.56%) and 7-formyl-4-methyl-cumarine (0.15%) in lovage essential oil is reported. Antibacterial and antifungal activities of mentioned oil were evaluated in vitro on five strains of microorganisms. It was found that lovage volatile oil (L .officinale) exhibits high antibacterial and antifungal properties in the range of concentrations 0.015-0.030%.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.513  

Abstract (PDF) 

Graphical Abstract: The new complexes [Ni(phen)₃][Ge(HCit)₂]•2H₂O (1), [Ni(phen)₃][Sn(HCit)₂]•3H₂O (2) (where phen is 1,10-phenanthroline, H₄Cit is citric acid) were obtained. The identity, composition, and thermal stability of the complexes were established by elemental analysis, thermogravimetry, and IR spectroscopy. According to the X-ray diffraction data, the bis(citrate)germanate / bis(citrate)stannate [Ge/Sn(HCit)₂]^2- carries out the role of the dianion while two halves of the nickel complexes with phenanthroline [Ni(Phen)₃]²⁺ are cations.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.506  

Abstract (PDF) 

Graphical Abstract: This paper reviews information on essential oil of Marrubium species (except M. vulgare) described until now regarding extraction, chemical composition and biological activities. Marrubium essential oils, although quantitatively poor, are rich in chemical composition. This composition consists especially of sesquiterpenoids and a little amount of monoterpenes. It varies from one species to another, sometimes within same species. Marrubium essential oils exhibit antioxidant and antimicrobial activities. However, because the lack of literature concerning essential oil of these species, further studies are necessary, particularly regarding their activities.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.502   

Abstract (PDF) 

Graphical Abstract: The features of the cement clinker when rice husk is used are investigated. The dependence of the raw mixture composition on the set product burning characteristics has been analysed using the software “CLINKER”. The mixture compositions have been identified on the basis of the chalk–clay–rice husk system, with the introduction of man-made stock of 6.0–18.0 mass %. The features of the phase composition and the binder properties, by varying the rice husk content, mixture ratio and burning temperature are shown.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.504

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Graphical Abstract: This paper reports on the synthesis of a new trinuclear homometalic mixed-valent iron carboxylate cluster with furan-2-carboxylic acid. The complex with the formula [Fe₂^IIIFe^IIO(C₄H₃OCOO)₆(H₂O)₃]∙0.5CH₃CN•2.25H2O was characterized by X-ray analysis that revealed that the compound crystalizes in the triclinic centrosymmetric group P-1, with the following unit cell parameters: a = 10.2758(6)Å, b = 11.5991(9) Å, c = 19.7349(15) Å, α = 105.060(7)°, β =  94.216(6)°, γ = 101.662(6)°.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.493   

Abstract (PDF) 

Graphical Abstract: The study was aimed at increasing solubility and dissolution rate of ketoprofen by using multicomponent crystallization approach with nicotinamide as additional material. The multicomponent crystallization was carried out by solvent evaporation method using 2-propanol as solvent. The solubility and dissolution test showed that the ketoprofen-nicotinamide multicomponent crystal has solubility and dissolution rate significantly higher than the solubility and dissolution rate of the pure ketoprofen.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.368

Abstract (PDF) 

Graphical Abstract: A series of homobi- and polynuclear zinc and cadmium coordination compounds supported by 1,2-cyclohexanedionedioxime and bridging bidentate ligands: 4,4'-bipyridyl, 1,2-bis(4-pyridyl) ethane, 1,3-bis(4-pyridyl) propane and dipiridil sulfide were characterized by the experimental techniques of ¹H and ¹³C NMR spectroscopy. Individual NMR data of compounds are consistent with their assignment as complexes.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.494

Abstract (PDF)

Graphical Abstract: The adsorption of strontium ions from aqueous solutions on nut shells activated carbons (samples CAN-7 and CAN-8) at different temperatures has been studied. The isotherm of adsorption of strontium ions from aqueous solutions on activated carbon CAN-7 has two inflection points at relatively small and high equilibrium concentrations. As the temperature increases, the adsorption values decrease, which indicates that the adsorption process is exothermic.