Chemistry Journal of Moldova

2020 Volume 15, no.2

THE STOICHIOMETRIC UNIQUENESS OF MULTIPLE CHEMICAL REACTION SYSTEMS IN CHEMICAL THERMODYNAMICS, KINETICS AND CATALYSIS – CONTRIBUTIONS OF PROFESSOR ILIE FISHTIK

Author(s):

Igor Povar


Field: Physical chemistry and chemical physics
Type: Invited paper
Issue: 2020 Volume 15, no.2
Pages: 7-28
Keywords: response reaction, chemical thermodynamics, kinetics, heterogeneous catalysis, stoichiometry.
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DOI: http://dx.doi.org/10.19261/cjm.2020.803

Abstract (PDF)
Graphical Abstract: The main scientific achievements of great significance accomplished by Professor Ilie Fishtik at the University of Iowa and the Worcester Polytechnic Institute, in several fields of the physical chemistry as chemical thermodynamics, kinetics and heterogeneous catalysis were revealed and briefly analysed. Fundamental equations of chemical thermodynamics within the De Donder (stoichiometric) approach were reformulated in terms of a special class of chemical reactions, called as response reactions. Using this approach, the unusual behaviour of chemical equilibrium systems, to interpret the apparent contradictions to Le Chatelier principle and to discover hitherto unnoticed thermodynamic identities, was rationalised. The stabilities of chemical species were formulated in terms of a certain class of stoichiometrically unique chemical reactions and their thermochemical characteristics. A completely new approach for the generation and simplification of kinetic mechanisms for complex reaction systems was developed and applied. Based on a new type of reaction networks, referred to as reaction route graphs, a systematic method of analysis and reduction of a microkinetic mechanism was established and employed.


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LC-MS ANALYSIS AND ANTIOXIDANT ACTIVITY OF THE HYDRO-ALCOHOLIC EXTRACT OF MELISSA OFFICINALIS L. FROM ALGERIA

Author(s):

Brahim Ben Aicha, Rachid Rouabhi, Salim Gasmi, Chawki Bensouici, Hichem Mohammedi, Imad Mennai


Field: Natural product chemistry and synthesis
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 78-87
Keywords: hydro-methanolic extract, Melissa officinalis L., LC-MS analysis, antioxidant activity.
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DOI: http://dx.doi.org/10.19261/cjm.2020.778

Abstract (PDF)
Supplementary Material (PDF)
Graphical Abstract: The present work focuses on evaluation of the chemical composition and antioxidant activity of the hydro-methanolic extract of Melissa officinalis from Algeria. The liquid chromatography-mass spectrometry analysis allowed the identification of six compounds: caffeic acid, caftaric acid, hydroxyjasmonic acid glucoside, caftaric acid glucoside, rosmarinic acid and sagerinic acid. The in-vitro antioxidant activity of the hydro-methanolic extract was evaluated by using four different methods including: radical scavenging assay (DPPH), scavenging activity (ABTS), cupric reducing antioxidant capacity, and ferric reducing power assay.  The extract exhibited a relatively strong antioxidant activity compared to the synthetic antioxidants. The highest radical scavenging activity was registered using DPPH and ABTS methods,  IC50= 20.53±2.64 μg/mL and 22.50±0.67 μg/mL, respectively. These results suggest that Melissa officinalis L. could be considered a potential source of natural antioxidants with potential interest in the agrochemical and pharmaceutical industries.


 


Downloads: 169

EXTRACTING CONDITIONS OPTIMIZATION AND BIOACTIVITY OF POLYSACCHARIDES FROM THE PODS OF HARICOT VERT

Author(s):

Nguyen Thi Thu Thuy, Do Hoang Giang, Pham Khac Linh, Nguyen Tien Dat


Field: Supramolecular chemistry
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 45-53
Keywords: polysaccharides extraction, optimization, haricot vert, bioactivity.
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DOI: http://dx.doi.org/10.19261/cjm.2020.795
 
Abstract (PDF)
Graphical Abstract: Polysaccharides from the pods of haricot vert (Phaseolus vulgaris L.) were extracted using a simple heating method, by varying extracting temperature, heating time, solid-to-liquid ratio, and solvent compositions. The obtained results were processed using statistical analysis that helped to identify the optimal conditions for the polysaccharides’ extraction process. This study represents a promising production method of bioactive polysaccharides extract in the food and pharmaceutical industry.   

 

Downloads: 89

DECOLOURISATION OF BEET SUGAR SYRUP USING ACTIVATED CARBON AND GLUCOSE OXIDASE ENZYME

Author(s):

Pezhman Zolfaghari, Neda Imani Payandeh, Mortaza Golizadeh, Afzal Karimi, Amirali Ebadi Fard Azar


Field: Industrial chemistry
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 54-61
Keywords: beet sugar syrup, decolourisation, activated carbon, hydrogen peroxide, glucose oxidase.
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DOI: http://dx.doi.org/10.19261/cjm.2020.775

Abstract (PDF)
Graphical Abstract: This paper presents the development and optimization of a new approach which combines the utilization of activated carbon and glucose oxidase enzyme for decolourisation of beet sugar syrup. The combining of the physical adsorption with the enzymatic reaction was managed to improve the decolourisation of beet sugar syrup from 35.29 to 83.68% compared to the basic adsorption by activated carbon after 120 min of operation under the optimum conditions. The maximum decolourisation efficiency by the coupled process was achieved at glucose oxidase dosage of 0.07 g, glucose concentration of 20 mM, and solution pH 7 at the temperature of 30ºC using 0.01 g of activated carbon particles. Given the high effectiveness, reusability, and the eco-friendly nature of the process, the proposed method can serve as an alternative to ordinary decoloursation techniques.



 

Downloads: 68

THE USE OF SOME NON-CONVENTIONAL METHODS IN CHEMISTRY OF BICYCLOHOMOFARNESENIC METHYL ESTERS

Author(s):

Alexandru Ciocarlan, Lidia Lungu, Svetlana Blaja, Ion Dragalin, Aculina Aricu


Field: Natural product chemistry and synthesis
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 69-77
Keywords: bicyclohomofarnesenic methyl ester, microwave irradiation, anodic electrooxidation, dye-sensitized photooxidation.
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DOI: http://dx.doi.org/10.19261/cjm.2020.791

Abstract (PDF)
Graphical Abstract: The present paper reports the results of microwave irradiation assisted method for the preparation of bicyclohomofarnesenic methyl esters versus classical Stoll and Hinder method. Moreover, the chemical transformations of bicyclohomofarnesenic methyl esters via anodic electrooxidation and dye-sensitized photooxidation were performed. A new method for the preparation of methyl 7-oxo-13,14,15,16-tetranorlabd-6,8(8)-dien-12-oate and the mechanism of electrochemical products formation are presented. The structure of all synthesized compounds was fully confirmed by spectral methods.


 

Downloads: 100

FACILE AND EFFICIENT SYNTHESIS OF XANTHENE DERIVATIVES MEDIATED BY LANTHANUM(III) NITRATE HEXAHYDRATE UNDER SOLVENT FREE CONDITIONS

Author(s):

Kabeer Ahmed Shaikh and Uddhav Nivrutti Chaudhar


Field: Organic chemistry
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 99-104
Keywords: lanthanum(III) nitrate, xanthene derivative, dimedone, β-naphthol, solvent free condition.
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DOI: http://dx.doi.org/10.19261/cjm.2020.774

Abstract (PDF)
Graphical Abstract: The present paper shows that lanthanum(III) nitrate hexahydrate can be used as mild and environment friendly homogeneous catalyst for an efficient one-pot multi-component synthesis of biologically active 1,8-dioxo-octahydroxanthene and 14H-dibenzo[a,j]xanthene derivatives. The solvent free condensation reaction of aromatic aldehydes and dimedone or β-naphthol was carried out at 70-80ºC during 10-30 min. The advantages of this eco-friendly synthesis route are numerous, and include the use of an inexpensive catalyst, high to excellent yield, short reaction time and high catalytic activity that can make this method an interesting alternative to multi-step approaches.


 
 
 

Downloads: 69

VARIATIONS OF PHOSPHORUS, SULPHUR AND NITROGEN CONTENT IN LICHENS IN THE FORMER MANUFACTURING AREAS

Author(s):

Vitālijs Lazarenko, Zenta Balcerbule, Vita Rudoviča, Arturs Vīksna


Field: Ecological chemistry
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 38-44
Keywords: phosphorus, nitrogen, sulphur, lichen, soil.
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DOI: http://dx.doi.org/10.19261/cjm.2020.751

Abstract (PDF)
Graphical Abstract: The aim of this research work was to evaluate the pollution level of phosphorus, sulphur and nitrogen in the former manufacturing areas (the former Kuprava drainage pipe factory and landfill site) and compare it with the Sita forest area levels using lichens as bioindicators. Additionally, the correlation between the content of these elements in lichens and soil was examined. The research results show that in the former drainage pipe factory area and landfill site, the levels of phosphorus, sulphur and nitrogen content were elevated in comparison with Sita forest. In the case of phosphorus and nitrogen contents, a positive correlation was observed between soil and lichen samples. 


 

Downloads: 81

COMPOUNDS REMOVED FROM THE CONDENSATION REACTION BETWEEN 2-ACETYLPYRIDINE AND 2-FORMYLPYRIDINE. SYNTHESIS, CRYSTAL STRUCTURE AND BIOLOGICAL EVALUATION

Author(s):

Roman Rusnac, Maria Botnaru, Nicanor Barba, Peter Petrenko, Yurii Chumakov, Aurelian Gulea


Field: Organic chemistry
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 88-98
Keywords: 1,3-bis(pyridin-2-yl)prop-2-en-1-one, Claisen-Schmidt condensation, intramolecular aldol condensation, Michael addition, substituted cyclohexanol.
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DOI: http://dx.doi.org/10.19261/cjm.2020.695   

Abstract (PDF) 
Graphical Abstract: The research is devoted to the study of unexpected products that formed as a result of the condensation reaction between 2-acetylpyridine and 2-formylpyridine under the Claisen-Schmidt reaction conditions. As a result, a sequence of reactions leading to the following compounds has been proposed: 1,3-bis (pyridin-2-yl) prop-2-en-1-one (3); 1,3,5-tri (pyridin-2-yl) pentane-1,5-dione (4); (2,4-dihydroxy-2,4,6-tri(pyridin-2-yl)cyclohexyl)(pyridin-2-yl)methanone (5) and (4-hydroxy-2,4,6-tri(pyridin-2-yl)cyclohexane-1,3-diyl)bis(pyridin-2-ylmethanone) (6) as well as 2-formylpyridine (1) and 2-acetylpyridine (2). The plausible mechanism of these chemical transformations has been proposed. All the obtained compounds demonstrate moderate antimicrobial, antifungal and antioxidant activity.


 

Downloads: 86

APPLICATION OF INNOVATIVE PROCESSES FOR GOLD RECOVERY FROM ROMANIAN MINING WASTES

Author(s):

Stefano Ubaldini, Igor Povar, Tudor Lupascu, Oxana Spinu, Francesca Trapasso, Daniele Passeri, Serena Carloni, Daniela Guglietta


Field: Ecological chemistry
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 29-37
Keywords: mining waste, gold, thiosulphate leaching, activated carbon, adsorption, desorption.
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DOI: http://dx.doi.org/10.19261/cjm.2020.718

Abstract (PDF)
Graphical Abstract: The application of a new hydrometallurgical process for gold extraction by thiosulphate leaching from Romanian mining wastes, coming from Balan and Deva deposits, was studied. There was obtained 85% of Au extraction after leaching; moreover, an integrated flow-sheet, including recycling of process solution and carbon, was outlined, based on results obtained at a laboratory scale, using a schematic chemical circuit of treatment. Global recovery of the process (leaching-adsorption-desorption-electrodeposition) of about 75-80% of Au was achieved. The developed integrated flow-sheet, allows to recycle the reagents during the process, with a loss of only 5-10%, in particular thiosulphate and alcohol, for each complete circuit of treatment.


 

Downloads: 58

SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF THE TETRANUCLEAR IRON(III) CLUSTER WITH SALICYLIC ACID

Author(s):

Viorina Gorinchoy


Field: Inorganic and coordination chemistry
Type: Research paper
Issue: 2020 Volume 15, no.2
Pages: 62-68
Keywords: homotetranuclear salicylate, iron(III), cluster, IR spectroscopy, X-ray crystal structure.
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DOI: http://dx.doi.org/10.19261/cjm.2020.758

Abstract (PDF)
Graphical Abstract: A new tetra-homonuclear iron(III) cluster, [Fe4O2(Sal)4(H2O)6]·4DMA·0.75H2O, where Sal= salicylic acid and DMA= N,N-dimethylacetamide consolidated via two µ3-oxo- and four salicylate-bridges was synthesized and characterized by IR spectroscopic method as well as by single crystal X-ray diffraction analysis. The structure of the obtained tetranuclear compound consists of four FeIII atoms in a “butterfly” arrangement. The coordination sphere of each of the two central FeIII atoms is generated by two μ3-oxo-bridging atoms and four oxygen atoms provided by the tridentate-bridging Sal2- ligands, while the coordination polyhedron of another two iron atoms involve six oxygen atoms from three water molecules, two salicylic and one μ3-oxigen atom. The Fe-O distances within Fe-O-Fe bridge are of 2.102(3) Å (for wing-body) and 2.038(3) Å (for body-body).





Downloads: 82