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OXIDATION OF ALIPHATIC PRIMARY ALCOHOLS BY TETRAKIS (PYRIDINE) SILVER DICHROMATE – A KINETIC AND MECHANISTIC APPROACH

OXIDATION OF ALIPHATIC PRIMARY ALCOHOLS BY TETRAKIS (PYRIDINE) SILVER DICHROMATE – A KINETIC AND MECHANISTIC APPROACH

Author: Amit Daiya, Deepika Sharma, Manju Baghmar, Pallvi Mishra, Shobha Sharma, Vinita Sharma
Abstract

The oxidation of nine aliphatic primary alcohols by tetrakis(pyridine) silver dichromate (TPSD) in dimethylsulfoxide leads to the formation of corresponding aldehydes. The reaction is first order with respect to TPSD. A Michaelis-Menten type kinetics is observed with respect to alcohols. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs= a + b [H+]. The oxidation of [1,1-2H2]ethanol (MeCD2OH) exhibits a substantial primary kinetic isotope effect (kH/kD = 5.85 at 298 K). The reaction has been studied in nineteen different organic solvents. The solvent effect was analysed using Taft's and Swain's multiparametric equations. The rate of oxidation is susceptible to both polar and steric effects of the substituents. A suitable mechanism has been proposed.

Keywords: Correlation analysis; alcohols; dichromate; kinetics; mechanism; oxidation.

EVALUATION OF CHROMATOGRAPHIC RETENTION DATA BY CLUSTER ANALYSIS. NEW ACHIEVEMENTS

EVALUATION OF CHROMATOGRAPHIC RETENTION DATA BY CLUSTER ANALYSIS. NEW ACHIEVEMENTS

Author: Tibor Cserháti, Mária Szőgyi
Abstract

The newest results in the application of cluster analysis a multivariate mathematical-statistical technique for the evaluation of large
retention data matrices are collected. The results are critically evaluated, and examples for the application in gas chromatography, liquid
chromatographic techniques such as thin-layer chromatography and high-performance liquid chromatography, as well as in electrically
driven systems are presented.

Keywords:

CHROMATOGRAPHY OF XENOBIOTICS IN BIOLOGICAL AND ENVIRONMENTAL MATRICES

CHROMATOGRAPHY OF XENOBIOTICS IN BIOLOGICAL AND ENVIRONMENTAL MATRICES

Author: Gyula Oros, Tibor Cserháti, Mária Szőgyi
Abstract

The newest results in the chromatographic analysis of xenobiotics present in biological and environmental matrices are compiled and the results are critically evaluated. Examples for the employment of preconcentration and prepurification technologies, gas chromatography using electron capture detection (ECD), nitrogen phosphor detector (NPD), various mass spectrometric detection methods (MS, MS/MS, etc), liquid chromatographic methodologies such as thin-layer chromatography (TLC), high performance liquid chromatographic methods (HPLC) as well as electrically driven systems are presented. The advantages and disadvantages of the various chromatographic technologies are shortly discussed and the efficacies of the methodologies are compared. Xenobiotics included in the review are volatile organic compounds (VOC), hydrocarbons and hydrocarbon-based pollutants, polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenols (PCB), other polyhalogenated compounds, pesticides, etc. The application of various chromatographic methods for the determination of xenobiotics in a wide variety of biological and environmental matrices is discussed in detail.

Keywords: xenobiotics; gas chromatography; liquid chromatography; electrically driven systems; biological and environmental matrices

CHROMATOGRAPHIC DETERMINATION OF PESTICIDES IN FOODS AND FOOD PRODUCTS

CHROMATOGRAPHIC DETERMINATION OF PESTICIDES IN FOODS AND FOOD PRODUCTS

Author: Tibor Cserháti, Mária Szőgyi
Abstract

The newest results in the chromatographic analysis of pesticides present in foods and food products are collected and the results are
critically evaluated. Examples for the employment of preconcentration and prepurification technologies, gas chromatography using ECD, NPD, MS and MS/MS detection methods, liquid chromatographic methodologies such as thin-layer chromatography, high performance liquid chromatographic methods as well as electrically driven systems are presented. The advantages and disadvantages of the various chromatographic technologies are shortly discussed and the efficacies of the methodologies are compared. Pesticides included in the review are insecticides, herbicides, acaricides, organophosphorous and organochlorine compounds The application of the chromatographic
methods for the determination of pesticides in a wide variety foods and food products is discussed in detail.

Keywords: pesticides, gas chromatography, liquid chromatography, electrically driven systems.

2ND INTERNATIONAL CONGRESS ON DEUTERIUM DEPLETION

2ND INTERNATIONAL CONGRESS ON DEUTERIUM DEPLETION

Author: Budapest, Hungary
Abstract

The 2nd International Congress on Deuterium Depletion was held on 17-18 May 2012 in Budapest, Hungary
(www.deuteriumdepletion.com), as a follow-up to the 1st International Symposium on Deuterium Depletion held in Budapest in the spring of 2010. The goal of the organizers was to provide a global and comprehensive update of the newest results and developments in the research of deuterium depletion, and to give the researchers and medical practitioners a new opportunity to get acquainted with this expanding field of science, share their results and experience. Researchers and practitioners from several countries (Hungary, USA, France, Romania, Russia and China) presented 16 lectures on the various biological effects of deuterium depletion in the field of cancer research, research and anti-aging science.

Keywords: deuterium, D-content variations, natural materials

CORRELATION ANALYSIS OF REACTIVITY IN THE OXIDATION OF SUBSTITUTED BENZALDEHYDES BY QUINOLINIUM FLUOROCHROMATE

CORRELATION ANALYSIS OF REACTIVITY IN THE OXIDATION OF SUBSTITUTED BENZALDEHYDES BY QUINOLINIUM FLUOROCHROMATE

Author: Jagrity Khatri, A. Choudhary, P. Purohit, R. Kumbhat, Vinita Sharma
Abstract

Oxidation of thirty six monosubstituted benzaldehydes by quinolinium fluorochromate (QFC) in dimethylsulphoxide (DMSO), leads to
the formation of corresponding benzoic acids. The reaction is of first order with respect to QFC. A Michaelis-Menten type kinetics was
observed with respect to the reactants. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs=a+b[H+]. The oxidation of [2H]benzaldehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen different organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton’s triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraperametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and metasubstituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.

Keywords: Correlation analysis; halochromate; kinetics; mechanism; oxidation

DEUTERIUM ISOTOPE SEPARATION IN THE CHEMICAL REACTION OF ALUMINIUM AMALGAM AND WATER

DEUTERIUM ISOTOPE SEPARATION IN THE CHEMICAL REACTION OF ALUMINIUM AMALGAM AND WATER

Author: László Kótai, József Lippart, István Gács
Abstract

Deuterium isotope separation process takes place in the reaction of the amalgamated aluminium metal surface and water. The reaction produces hydrogen gas with ~40 ppm deuterium content and the formed aluminium hydroxide gel is enriched in deuterium. The theoretical separation factor is s=3.9. Besides the kinetic isotope effect, the key factor in the separation process is the H2O+HD=HDO+H2 exchange reaction. Since only a low amount of amalgam forms on the aluminium surface, the overvoltage difference of the deuterium and the hydrogen on the mercury does not play key role in the process. The main role of the amalgam formation is embodied in the decomposition of the stable oxide layer on the aluminium surface, thus ensuring free metallic surfaces for the reaction with the water.

Keywords: aluminium amalgam; deuterium-depleted hydrogen; deuterium isotope separation

CHARACTERIZATION OF SYNTHETIC VOLTAITE ANALOGUES

CHARACTERIZATION OF SYNTHETIC VOLTAITE ANALOGUES

Author: István E. Sajó
Abstract

Recently new NH4- and Mg-containing minerals of the voltaite group have been discovered. As they were found in minute amounts and are intimately intergrown with their associated minerals, a number of their properties could not be measured and characterized properly. The four pure end members of the solid solution series were synthesized and characterized, that made possible the reliable identification of natural solid solutions within the boundaries of this phase composition range.

Keywords: Inorganic frameworks, experimental mineralogy, mixed valence solids

SOLID PHASE SULPHATIZING OF ZINC FERRITE SPINEL WITH IRON SULPHATES AS AN ENVIRONMENTAL FRIENDLY WAY FOR RECOVERING ZINC

SOLID PHASE SULPHATIZING OF ZINC FERRITE SPINEL WITH IRON SULPHATES AS AN ENVIRONMENTAL FRIENDLY WAY FOR RECOVERING ZINC

Author: Anurag Saini, László Kótai, István E. Sajó, Imre Miklós Szilágyi, Károly Lázár, Zoltán May, Péter Fazekas, István Gács, Vinita Sharma, Kalyan K. Banerji
Abstract

The scarcely reactive zinc ferrite can be decomposed in solid phase to water-soluble ZnSO4 and water-insoluble Fe2O3 polymorphs by excess of solid iron(II or III) sulphates at 650°C in 4 h. Since SO3 forms in situ from the Fe2(SO4)3 as well as anhydrous Fe2(SO4)3 forms in the thermal oxidation of iron(II) sulphate, therefore the gaseous SO3 is the active sulphatization agent in the reaction of the hydrated iron(II and III) sulphates and the zinc ferrite. The sulphatization process were monitored by XRD, TG/DTA-MS, Mössbauer, Raman and IR-spectroscopy and the changes in reaction’s heat and Gibbs energy are reported. The Fe2O3 polymorphs formed is worth processing into iron(III) sulphate by sulphuric acid. Since the Fe2(SO4)3 formed in this way can be recycled to the sulphatization process, the only reagent consumed is the sulphuric acid. Therefore, these selective sulphatization reactions can be taken as “iron salts mediated” decompositions of zinc ferrite into ZnSO4 and Fe2O3 by sulphuric acid.

Keywords: Zinc ferrite; Oxides; Sintering; Sulphatization

METAL ELEMENTS, ORGANIC AGENTS IN A HERBAL REMEDY, SPECIES THYMI COMPOSITA, AND ITS DRUGCONSTITUENTS

METAL ELEMENTS, ORGANIC AGENTS IN A HERBAL REMEDY, SPECIES THYMI COMPOSITA, AND ITS DRUGCONSTITUENTS

Author: Klára Szentmihályia, Zoltán Maya, Mária Then, Mária Hajdú, Andrea Böszörményi, Andrea Balázs, Éva Lemberkovics, Gabriella Marczal, Éva Szőke
Abstract

Beside plant drugs the application of herbal mixtures using in several indication fields is very popular in our time. Since these herbal mixtures contain several bioactive agents, their analysis may cause difficulties. Therefore the description of measurements of components and their standardization is generally missing from the Pharmocopoeias. The examined Species thymi composita (STC) is highly effective because of its cholagog, carminative, expectorant, anticatarrhal etc. activity. STC is the mixture of Althaeae radix et folium (marshmallow leaf and root), Verbasci flos (mullein flores), Liquiritiae radix (liquorice root) and Thymi herba (thyme). The macroscopic and microscopic identification of components, phytochemical characterization have been described, the element composition of the herbal mixture, plant drugs constituents and teas was studied and the in vitro element absorption was examined. It has been stated that the STC could be characterized by its mucilage content and volatile oil composition. STC and its tea contain elements as well and the in vitro absorption of some of elements showed relatively high amount. The presence of bioactive compounds, volatile oil components, mucilage and elements may be jointly important in the complex effect, although the relatively higher Mg and Zn content in the tea is particularly relevant that acts via signal transduction process.

Keywords: herbal remedy, Species thymi composita, respiratory diseases, essential oil, elements