Open Access Published by De Gruyter Open Access

Volume 3 Issue 4

December 2005

Issue of Open Chemistry

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Journal Overview

Open Access December 1, 2005

QSPR study on pKa values of N-methoxy-polynitroaniline derivatives

Adrian Beteringhe

Page range: 585-591

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Abstract

A QSPR study is presented for acidities of thirteen N-methoxy-polynitroaniline derivatives. Hammett σ values are known for meta and para substituents, and in the present study values are introduced for ortho-substituents in these N-methoxy-polynitroaniline derivatives. Hammett σ values for ortho-substituents in these N-methoxy-polynitroaniline derivatives were obtained by multiplying para values with 0.65.

Open Access December 1, 2005

A kinetic method for para-nitrophenol determination based on its inhibitory effect on the catalatic reaction of catalase

Claudia Mureşanu, Lucian Copolovici, Florina Pogącean

Page range: 592-604

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Abstract

The inhibitory effect of para-nitrophenol on the catalytic reaction of catalase was investigated. Michaelis-Menten kinetic parameters were determined from Lineweaver-Burk plots obtained in the absence or in the presence of the inhibitor. The inhibitor pattern, revealed by the Lineweaver-Burk plots, suggested a fully mixed inhibition mechanism. Spectrophotometric monitoring of the indicator reaction: $$H_2 O_2 \xrightarrow{{catalase,para - nitrophenol}}H_2 O + \tfrac{1}{2}O_2 $$ in conjunction with initial rate measurements was employed for the kinetic determination of the inhibitor. Calibration plots of initial rate vs. para-nitrophenol concentration were linear in the concentration range 0.9·10−5–2.5·10−5 mol/L and the detection limit was 3·10−6 mol/L (417 μg/L) para-nitrophenol. Interferences from other phenolic compounds like orto-cresole, meta-and orto-nitrophenol were observed.

Open Access December 1, 2005

Oxygen detection using yttria-stabilized zirconia thin films doped with platinum

Dimitre Dimitrov, Ceco Dushkin

Page range: 605-621

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Abstract

Yttria stabilized zirconia (YSZ) thin films are obtained using both spray-pyrolysis and dip-coating. The ability of YSZ films incorporated with platinum nanospecies (Pt-YSZ) to detect oxygen is compared with that of pure YSZ thin films using a new experimental setup. With this system, the surface electrical resistance of the films as a function the oxygen content is measured at a fixed temperature. In addition, the effects of thermal annealing on the oxygen sensitivity of the films are observed. Platinum doped samples, Pt-YSZ, show different kinetics of carrier diffusion as compared to pure YSZ samples.

Open Access December 1, 2005

Reactions of substituted furo[3,2-b]pyrrole-5-carboxhydrazides and their biological activity

Renata Ga<parová, Daniel Zbojek, Margita Lácová, Katarína Král'ová, Anton Gatial, Branislav Horváth, Alžbeta Krutošíková

Page range: 622-646

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Abstract

The reactions of substituted furo[3,2-b]pyrrole-5-carboxhydrazides 1 with 5-arylfuran-2-carboxaldehydes 2, 4,5-disubstituted furan-2-carboxaldehydes 3 and thiophene-2-carboxaldehyde 4 has been studied. The advantage of microwave irradiation on some of these reactions was reflected in the reduced reaction time and increased yields. Reactions of 1 with 4-substituted 1,3-oxazol-5(4H)-ones 11 led to diacylhydrazines 13 or to imidazole derivatives 14 depending on the temperature. 1,2,4-Triazole-3-thione 17 was synthesized by two-step reaction of 1 with phenylisothiocyanate and subsequent base-catalyzed cyclization of thiosemicarbazide 16. The effects of hydrazones 5–10 on inhibition of photosynthetic electron transport in spinach chloroplasts and chlorophyll content in the antialgal suspensions of Chlorella vulgaris were investigated.

Open Access December 1, 2005

New computer program to calculate the symmetry of molecules

Ali Ashrafi, Mohammad Ahmadi

Page range: 647-657

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Abstract

In this paper we, present some MATLAB and GAP programs and use them to find the automorphism group of the Euclidean graph of the C80 fullerence with connectivity and geometry of Ih symmetry point group. It is proved that this group has order 120 and is isomorphic to Ih≊Z2×A5, where Z2 is, a cyclic group of order 2 and A5 is the alternating group on five symbols.

Open Access December 1, 2005

A convenient synthesis of long-chain 4-substituted benzyloxycarbonyl alkanethiols for the formation of self assembled monolayers on metal substrates

Polina Angelova, Kalina Kostova, Karsten Hinrichs, Dimiter Tsankov

Page range: 658-667

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Abstract

New 4-substituted benzyl esters of 16-mercaptohexadecanoic acid were prepared by developing a practicable synthetic procedure and using readily available staring materials. The compounds synthesized have been characterized by NMR, MS, IR spectra and elemental analysis. The mercapto derivatives are precursors for the formation of self-assembled monolayers on metal substrates.

Open Access December 1, 2005

Laser assisted selective chemical metalization of Al2O3 films

Emil Krumov, Dimitar Popov, Nikolay Starbov

Page range: 668-673

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Abstract

Thick aluminum oxide films are prepared on Al plates by anodizing. On the ceramic surface thus obtained a very thin Ag film is deposited via vacuum thermal evaporation. The Ag/Al2O3/Al samples prepared are irradiated by Nd:YAG laser through a suitable metal mask in order to remove the top metal film in the exposed areas. Thus, a negative silver image of the copied mask is obtained. Further, the samples are processed in Ni electroless chemical bath activated by the rest of silver. All processing steps are studied by scanning electron microscopy (SEM). EDS X-ray mapping is applied to study the final distribution of Al and Ni in the processed areas. In addition, the DC conductivity of the fabricated Ni wires obtained is measured. The proposed new method for selective chemical deposition of electroconductive Ni onto laser microstructured Ag/Al2O3/Al samples is simple, versatile and not restricted to the metal/ceramic system studied as well as to the electroless deposited metal.

Open Access December 1, 2005

Molecule dynamics and combined QM/MM study on one-carbon unit transfer reaction catalyzed by GAR transformylase

Qing-An Qiao, Yueqing Jin, Zhengting Cai, Rongjun Qu, Chuanlu Yang, Meishan Wang

Page range: 674-682

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Abstract

Both a molecule dynamic study and a combined quantum mechanics and molecule mechanics (QM/MM) study on Glycinamide ribonucleotide transformylase (GAR Tfase) catalytic mechanism are presented. The results indicate a direct one-carbon unit transfer process but not a stepwise mechanism in this reaction. The residues near the active center can fix the cofactor (N10-formyltetrahydrofolate) and GAR in proper relative positions by a H-bond network. The transition state and the minimum energy pathway are located on the potential energy surface. After all the residues (including H2O molecules) are removed from the system the activation energy has increased from 145.1 kJ/mol to 243.3 kJ/mol, and the formly transfer reaction is very hard to achieve. The interactions between coenzyme, GAR and residues near the reactive center are discussed as well.

Open Access December 1, 2005

Synthesis, structural and conformational study of selected N-substituted phthalimides

Isabel Iriepa, F. Javier Villasante, Enrique Gálvez, Antonio Herrera, Angel Sánchez, Felix Cano

Page range: 683-704

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Abstract

This paper synthesizes N-substituted phthalimides derived from nitrogen heterocycles as potential 5-HT4 ligands by using the Mitsunobu reaction. Conformational studies of some of the new compounds have been conducted using 1H and 13C-NMR spectroscopy. Proton and carbon resonances were achieved through the application of one-dimensional selective NOE, two-dimensional NMR techniques-homonuclear COSY-45, NOESY and heteronuclear 1H-13C HMQC correlated spectroscopy- and double resonance experiments. The crystal structure of compound 1 was determined by X-ray diffraction.

Open Access December 1, 2005

Oxidative polymerization of acrylamide in the presence of thioglycolic acid

Cemal Özeroğlu, Sacide Erdoğan

Page range: 705-720

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Abstract

Chemical polymerization of acrylamide at room temperature was examined by using thioglycolic acid-cerium (IV) sulfate and thioglycolic acid-KMnO4 redox systems in acid aqueous medium. Water soluble polyacrylamides containing thioglycolic acid end groups were synthesized. The effects of the molar ratio of acrylamide to Ce(IV) nAAm/nCe(IV), the polymerization time, the temperature, the monomer concentration, the molar ratio of cerium (IV) sulfate to thioglycolic acid and the concentration of sulfuric acid on the yield and molecular weight of polymer were investigated. Lower molar ratios of acrylamide/Ce(IV) at constant monomer concentration resulted in an increase in the yield but a decrease in molecular weight of polymer. The increase of reaction temperature from 20 to 70°C resulted in a decrease in the yield but generally resulted in a constant value for the molecular weight of polymer. With increasing polymerization time, the yield and molecular weight of polymer did not change substantially. Ce(IV) and Mn(VII) ions are reduced to Ce(III) and Mn(II) ions respectively in the polymerization reaction. The existence of Ce(III) ion bound to polymer was investigated by UV-visible spectrophotometry and fluoresce measurements. The amount of Mn(II) incorporated into the polymer was determined using graphite furnace atomic absorption spectrometry. The mechanism of this phenomenon is discussed.

Open Access December 1, 2005

The influence of temperature and photoinitiator concentration on photoinitiated polymerization of diacrylate monomer

Lavinia Macarie, Gheorghe Ilia

Page range: 721-730

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Abstract

The behavior of p-methoxybenzoyldiphenylphosphine oxide, previously synthesized, as a photoinitiator for the polymerization of diacrylate monomer, in the presence of 3% (w/w) tertiary amine (triethyl amine) as synergist additive, was studied. The influence of temperature in the range 30–90°C at 3% (w/w) photoinitiator concentration and the influence of the photoinitiator concentration in the range 0.5–3.5% (w/w) at 30°C was investigated by differential scanning photocalorimetry (photo-DSC). In all experiments the photopolymerization was performed at constant light intensity (3 mW cm−2). The maximum conversion was obtained at temperature of 90°C at 3% (w/w) photoinitiator concentration and 3% (w/w) triethyl amine. The optimal concentration of photoinitiator to obtain maximum conversion was 3% (w/w), at 30°C. No thermal polymerization occurred at higher temperature.

Open Access December 1, 2005

SVD-based principal component analysis of geochemical data

Petr Praus

Page range: 731-741

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Abstract

Principal Component Analysis (PCA) was used for the mapping of geochemical data. A testing data matrix was prepared from the chemical and physical analyses of the coals altered by thermal and oxidation effects. PCA based on Singular Value Decomposition (SVD) of the standardized (centered and scaled by the standard deviation) data matrix revealed three principal components explaining 85.2% of the variance. Combining the scatter and components weights plots with knowledge of the composition of tested samples, the coal samples were divided into seven groups depending on the degree of their oxidation and thermal alteration. The PCA findings were verified by other multivariate methods. The relationships among geochemical variables were successfully confirmed by Factor Analysis (FA). The data structure was also described by the Average Group dendrogram using Euclidean distance. The found sample clusters were not defined so clearly as in the case of PCA. It can be explained by the PCA filtration of the data noise.

Open Access December 1, 2005

Inclusion-dependent mechanism of modification of cyclodextrins with heterocycles

Robert Musiol, Tomasz Girek

Page range: 742-746

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Abstract

Mono(6-deoxy-dimethylpyridinium)-β-cyclodextrins have been synthesized in reaction of mono (p-toluenesulfonyl) derivative of β cyclodextrin with the appropriate lutidine under microwave irradiation and conventional conditions. The results indicate that the mechanism consists of inclusion complex formation.

Open Access December 1, 2005

Investigation of the extraction equilibrium of ion-association complexes of molybdenum (VI) with some polyphenols and thiazolyl blue. extraction-spectrophotometric determination of molybdenum

Atanas Dimitrov, Vania Lekova, Kiril Gavazov, Boyan Boyanov

Page range: 747-755

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Abstract

The extraction process of ternary ion-association complexes of molybdenum (VI) with some polyphenols (4-nitrocatechol, 2,3-dihydroxy naphthalene) and thiazolyl blue has been investigated by using an extraction-spectrophotometric method. The optimum conditions for their quantitative preparation in aqueous medium and subsequent extraction into an organic solvent have been found. The extraction, distribution and association constants, and the recovery factors have been calculated. The composition of the complexes has been determined. A precise, sensitive and simple extraction-spectrophotometric method for determination of molybdenum in products from ferrous metallurgy has been developed.

Open Access December 1, 2005

Inherent safety evaluation in process plants— a comparison of methodologies

Parisa Abedi, Mohammad Shahriari

Page range: 756-779

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Abstract

A global population increase and an improved standard of living are generally expected. To meet these demands, an increased production of chemicals will be necessary while protecting human health and the environment. However, most current methods of chemical production are unsustainable. New designs must result in plants that assure process and operator safety, the sustained health of workers and the community, and the protection of the environment. Traditional safety precautions and process controls minimize risk but cannot guarantee the prevention of accidents followed by serious consequences. Therefore, the general approach to environmental and safety problems must be changed from reactive to proactive. One way is to further develop the concept of inherent safety. In this paper some methods for inherent safety evaluations are reviewed. The aim of the study is to analyze the different tools available for inherent safety evaluation and identify the most important criteria in determining the inherent safety of a process plant. A model is proposed to show the interactions of different factors on the inherent safety level of a process and the model is illustrated by a case study.

Open Access December 1, 2005

The crystal structure of 1-(4-chlorophenyl)-3-(4-methylbenzoyl)thiourea

Aamer Saeed, Masood Parvez

Page range: 780-791

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Abstract

1-(4-Chlorophenyl)-3-(4-methylbenzoyl)thiourea was synthesized and characterized by IR,1H and 13C NMR, mass spectroscopy and the elemental analysis. The crystal structure was confirmed from single crystal X-ray diffraction data. It crystallizes in the monoclinic space group P21/c with unit cell dimensions a=12.038(3), b=6.330(6), c=18.912(5) Å and β=100.32(3)°. There is a strong intramolecular hydrogen bond of the type N−H...O, with distance N1...O1=2.659(3) Å. The structure is composed of dimers related by inversion centers. The dimers are formed by intermolecular interactions of the type N−H...S with N...S separation of 3.440(2) Å. The mass fragmentation pattern has also been discussed.

Open Access December 1, 2005

Synthesis of novel tryptamine and β-carboline derivatives via palladium-catalyzed reaction of bromotryptamine with organic boronic acids

Melinda Fekete, Pál Kolonits, Ngo Hien, Lajos Novák

Page range: 792-802

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Abstract

New tryptamine 5, 7 and β-carboline derivatives 3 were preparated by palladium-catalyzed coupling reaction of 5-bromotryptamine 1 with aryl boronic acids.

Open Access December 1, 2005

Preparation of a set of selectively protected disaccharides for modular synthesis of heparan sulfate fragments: toward the synthesis of several O-sulfonated [β-D-GlcUA-(1→4)-β-D-GlcNAc]OPr types

Hammed Hassan

Page range: 803-829

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Abstract

A concise method for a stereocontrolled synthesis of a set of selectively protected disaccharides is reported. Coupling of the donor 11 onto acceptors 23 and 24, promoted by trimethylsilyl triflate-N-iodosuccinimide (TMSOTf-NIS), generated the disaccharides 25 and 26. Under typical conditions, condensation of the fully protected donor 12 onto acceptors 23 and 24 produced the disaccharides 27 and 28. The building blocks 25–28 were prepared in moderate yields having exclusive β-stereoselectivity. A unique pattern of protecting groups distinguished clearly between positions to be sulfated and functional groups remaining as free hydroxyl groups. Acetyl and/or levulinoyl esters temporarily protected the positions to be sulfated, while benzyl ethers were used for permanent protection. The anomeric positions were protected as allyl ethers, whereas the 4′-positions were masked as p-methoxybenzyl (PMB) ethers. The orthogonality of the PMB and allyl groups can then be used for further elongation of the chain by recurrent deprotection and activation steps. The hydroxyl group, OH-6, of glucosamine moieties was protected as a TBDPS ether to avoid oxidation. A five-step deprotection/sulfonation sequence was applied to the disaccharide 27 to generate the corresponding sulfated [β-D-GlcUA-2-OSO3Na-(1→4)-β-D-Glc pNAc]-(1→O-Pro) 34.

Open Access December 1, 2005

A comparison of sequential extraction procedures for fractionation of arsenic, cadmium, lead, and zinc in soil

Pavel Tlustoš, Jiřina Száková, Alena Stárková, Daniela Pavlíková

Page range: 830-851

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Abstract

Twelve soil samples differing in physicochemical properties and total element contents were extracted by three sequential extraction procedures to determine As, Cd, Pb, and Zn bound to individual soil fractions and are defined by individual operational procedures. In the case of arsenic, two additional sequential extraction schemes were designed entirely for fractionation of soil containing arsenic were tested. The results confirmed that determination of element proportions bound to individual soil fractions is strongly dependent on the extracting agent and/or procedure applied within individual extracting schemes. As expected, absolute values of the elements released among the individual extracting procedures are weakly comparable. More reliable results were determined for the more mobile soil elements i.e. cadmium and zinc, in the fractions characterizing the most mobile proportions of investigated elements where significant correlations with basic soil characteristics were observed. In contrast, ambiguous results were observed for As and Pb, for both the individual extraction procedures and the effect of the soil characteristics. Regardless of the studied element, the poorest results were determined for reducible and oxidizable soil fractions. The application of at least two independent procedures or modification of the extraction scheme according to element investigated and/or particular soil characteristics can also be helpful in definition of element pattern in soils in further research.

Open Access December 1, 2005

The effect of flame coal oxidation on the solid and soluble products of its extraction

Robert Pietrzak, Helena Wachowska, Piotr Nowicki

Page range: 852-865

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Abstract

Solid and soluble products of THF and CH2Cl2 extraction of flame coal oxidised by four different oxidising agents (peroxyacetic acid (PAA), 5% HNO3, O2/Na2CO3, air/125 °C) were studied by elemental analysis and FTIR. The extraction yield with THF was much higher than that with CH2Cl2 for all samples. The greatest changes in elemental composition were in the extracts from coal oxidised by nitric acid. The sulphur content was lowest in extracts from coal oxidised with 5% HNO3 and PAA. FTIR confirmed that coal treatment with nitric acid incorporates nitrogen into the coal structure.

About this journal

Open Chemistry is a peer-reviewed, open access journal that publishes original research, reviews, and communications in the fields of chemistry in an ongoing way. Our central goal is to provide a hub for researchers working across all subjects to present their discoveries, and to be a forum for the discussion of the important issues in the field.

There are no submission charges. In order to sustain the production of our fully-refereed open access journal, each article accepted for publication in Open Chemistry is subject to Article Processing Charges (APC).

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Heterogeneous nanophotocatalysts based on polyoxometalate
Submission deadline: 31.05.2023
Phytochemicals, biological and toxicological analysis of aromatic medicinal plants
Submission deadline: 30.06.2023
Advanced Nanomaterials for Energy, Environmental and Biological Applications
Submission deadline: 31.08.2023
Marine Environmental Sciences and significance of the multidiscplinary approaches for assessing pollutions, remedies, and predictions
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