| Author (s): |
Lavinel G. Ionescu
|
| Title: |
COSTIN D. NENITZESCU (1902 -1970) 100th ANNIVERSARY OF HIS BIRTH |
| Abstract: |
Costin D. Nenitzescu was born in Bucharest in 1902 and passed away in Busteni, Romania in 1970. He obtained primary and secondary education in Romania and began university studies at the Swiss Federal Polytechnic Institute in Zurich. Later, he moved to the Technische Hochschule in Munchen (Munich) where he worked with Hans Fischer and obtained the Doctor of Engineering Degree in 1925. During the same year, he returned to Romania where he spent the rest of his life working, first at the University of Bucharest (1925-1935) and then at the Polytechnic Institute (1935-1970). Costin D. Nenitzescu is considered the founder of the School of Modern Organic Chemistry in Romania. He has published approximately 300 (three hundred) scientific articles, twenty books and treatises dealing mainly with organic chemistry, and authored about forty patents. Several organic reactions bear his name. Costin D. Nenitzescu s work includes the chemistry of indole and pyrrole, Romanian petroleum, nitro derivatives, reactions catalyzed by aluminum chloride, pyrytium salts, aromatic alkylation, cyclobutadiene, cyclooctatetraene, annulenes, carbonium ion reactions, eliminations, oxidations, and additions.
|
| Keywords: |
History of Chemistry, Aliphatic and Aromatic Alkylation, Nenitzescu Indole Synthesis, Naphthenic Acids, Mechanistic Organic Chemistry.
|
| Year: |
2002
|
| Initial page: |
1
|
| Final page: |
10
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.4_2002.pdf |
|
|
| Author (s): |
Paul Chirita, Mircea Preda, Olimpia Rusu
|
| Title: |
NATURAL PYRRHOTITE DISSOLUTION IN AQUEOUS SOLUTION |
| Abstract: |
The effects of some metal (II) ions on the natural pyrrhotite dissolution in hydrochloric acid solutions were studied Our results suggest that the rate of pyrrhotite dissolution increases in the presence of Sn2+ ion. Ions like Ni2+, Co2+, Cu2+, Zn2+ do not appear to have any effect on pyrrhotite dissolution in hydrochloric acid solutions. The magnitude of the activation energy (23.31 k.J mol-1 ) is in agreement with a mechanism controlled by a diffusion process.
|
| Keywords: |
pyrrhotite, nonoxidative dissolution, activation energy, iron minerals.
|
| Year: |
2002
|
| Initial page: |
11
|
| Final page: |
17
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.14_2002.pdf |
|
|
| Author (s): |
Erol ince and S. ismail Kirbaslar
|
| Title: |
LIQUID-LIQUID EQUILIBRIA OF THE WATER+ETHANOL+DIMETHYL ADIPATE TERNARY SYSTEM |
| Abstract: |
Liquid-liquid equilibrium data for the terna1y system water-ethanol-dimethyl adipate (dibasic ester) have been determined experimentally at 298.15±0.20, 308.15±0.20, and 318.15±0.20 K. Tie-line compositions were correlated by the Othmer-Tobias method. The UNIFAC method was used to predict the phase equilibrium in the system using the interaction parameters determined from experimental data between the CH3, CH2, OH, CH3COO and H20 groups. Distribution coefficients and separation factors were evaluated for theimmiscibility region
|
| Keywords: |
ethanol, dimethyl adipate, liquid-liquid extraction, ternary systems.
|
| Year: |
2002
|
| Initial page: |
19
|
| Final page: |
31
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.21_2002.pdf |
|
|
| Author (s): |
A.Reiss, G.Bratulescu, A.Kriza, N.Muresan
|
| Title: |
TRANSITION METAL COMPLEXES OF HETEROCYCLIC LIGANDS. PART VI. COMPLEXES OF 5-HYDROXY-6-MERCAPTO-BENZO[a]PHENAZINE WITH Co(II), Ni(II), Cu(II), Zn(II) AND Cd(II) |
| Abstract: |
The paper reports the conclusions about the structure of jive new romp/exes of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with the heterocyclic ligand, 5-hydroxy-6-mercapto- benzo[a] phenazine (H2L). These were obtained by elemental analysis, IR, UV-VIS and EPR spectral analysis, conductivity and magnetic susceptibility measurements, and thermal analysis. Bacteriological studies revealed that the ligand and the complexes possess moderate antimicrobial activity.
|
| Keywords: |
heterocyclic ligand; antibacterial activity; thermal decomposition; activated energies; transition metal complexes.
|
| Year: |
2002
|
| Initial page: |
33
|
| Final page: |
38
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.34_2002.pdf |
|
|
| Author (s): |
Ion Ganescu, George Bratulescu, Ion Papa, Anca Ganescu, Daniela Cartana and Cristian Tigae
|
| Title: |
NEW MIXED TETRADENTATE CHELATES OF Co(III) WITH ETHYLENDIIMINO-BIS-DIBENZOYLMETHANE |
| Abstract: |
Five new chelates of Co(III) of the [Co(dibenzec)(amine)2]+ type (dibenzec.H2-ethylenediimino-bis-dibenzoylmethane: C32H28N202, amine=aniline, o-anisidine, p-toluidine, m-xilidine, a-naphtilamine) were synthetized and characterized by isolation of thirty-four new complex salts by means of the double decomposition reactions. The thermal stability of the complexes was studied by means of differential thermal analysis. The structural properties were discussed on the basis of IR and UV spectra
|
| Keywords: |
Co(III), chelates, complex salts, structure chromium (III).
|
| Year: |
2002
|
| Initial page: |
39
|
| Final page: |
48
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.40_2002.pdf |
|
|
| Author (s): |
Ivo Vedana, Arno Muller and Lavinel G. Ionescu
|
| Title: |
PHYSICAL AND CHEMICAL PROPERTIES OF CONVENTIONAL PATTERN WAX AND REFORMULATED PATTERN WAX USED IN INVESTMENT METAL CASTING. |
| Abstract: |
The present study reports experimental results obtained for the physical and chemical properties of conventional or standard pattern wax and reformulated pattern wax blended in order to obtain maximum efficiency for possible recycling in the investment metal casting industry. Some of the properties determined included melting point, flash point, water content, ash content, volumetric expansion, hardness, refractive index, infrared and ultraviolet spectra, thermal behavior, curves obtained by DSC, DTA, and TGA. The reformulated wax was shown to be relatively stable and good for industrial use after twelve simulated recycling steps.
|
| Keywords: |
Pattern Wax, Metal Casting, Dewaxing, Recycling of Pattern Wax.
|
| Year: |
2002
|
| Initial page: |
49
|
| Final page: |
62
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.50_2002.pdf |
|
|
| Author (s): |
Ion Ganescu, George Bratulescu, Ion Papa, Anca Ganescu, Alin Barbu and Viorica Popescu
|
| Title: |
SOLVATION OF THE [Cr(NCS)4(IMIDAZOLE)2] ION IN ETHANOL-WATER MIXTURES |
| Abstract: |
Salvation kinetics of [Cr(NCS)4(imidazole)2]- has been studied in ethanol-water mixtures at different temperatures. The first stage of the solvation consists of two competitive reactions: two NCS- ions are exchanged, presumably, by water molecules and simultaneously an imidazole molecule by ethanol, the latter in a second-order reaction, accelerated by hydrogen ions. The exchange of the amine is followed by the substitution of the first two NCS- ions. The third and fourth NCS- ions are substituted only in neutral and slightly acidic solutions. Kinetic parameters have been determined for reactions (1), (2), and (4). The influence of the solvent composition and acidity is discussed
|
| Keywords: |
complexes of chromium, competitive reactions, mechanism, kinetic parameters, water-ethanol solution.
|
| Year: |
2002
|
| Initial page: |
63
|
| Final page: |
72
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.65_2002.pdf |
|
|
| Author (s): |
Carlos R. Wolf and Emir Grave
|
| Title: |
A STUDY OF PARAMETERS RELATED TO ANALYSIS OF TRANSITION TEMPERATURES AND ENTHALPIES OF POLYPROPYLENE BY DIFFERENTIAL SCANNING CALORIMETRY (DSC) |
| Abstract: |
Polypropylene is a thermoplastic polymer, widely employed by converter industries to produce different plastic objects. In order to control and optimize the final properties of the polypropylene material, the evaluation of transition temperatures and enthalpies by Differential Scanning Calorimetry (DSC) has a very important role. Therefore, it is fundamental to know how the analytical conditions influence the results. In this study heating and cooling rates, 10°C/min and 20°C/min, and two different rates of nitrogen flow, 20mL/min and 50mL/min were investigated. It was concluded that thermal properties are influenced by rates of heating and rates of nitrogen flow. Best precision was obtained with the low heating rate, 10°C/min, and high flow rate, 50mL/min. These conditions are being used with the DSC method for polyolefin quality control and material characterization.
|
| Keywords: |
Polypropylene, Differential Scanning Calorimetry, Thermal Analysis.
|
| Year: |
2002
|
| Initial page: |
73
|
| Final page: |
78
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.75_2002.pdf |
|
|
| Author (s): |
Cornel Tarabasanu Mihaila, Lavinia G. Hinescu, Cristian Boscornea, Carmen Moldovan, Mihai E. Hinescu
|
| Title: |
METAL COMPLEX TETRAIZOINDOLES AS SENSOR MATERIALS |
| Abstract: |
The paper presents the synthetic routes for obtaining some organic semiconductors and their characterization in order to use in thin film deposition for gas sensing devices. An original technique was used to control the molecular weight of polymeric phthalocyanine. We have fabricated devices consisting of evaporated thin films of copper, nickel, and iron phthalocyanines onto interdigital electrodes and estimated the electrical conductivity by in-situ measurements. The films were evaporated onto substrates (gold or aluminum) which were entirely integrated in the standard CMOS (capacitor metal oxide semiconductor) technology. The objectives of this work were to improve the synthesis methods of organic metal-complex tetraizoindoles and their polymers and to evaluate their electrical response and thermal stability as evaporated thin films. We have also investigated the variation of polymers conductivity and sublimation yield with the average molecular weight. We found that for polymeric phthalocyanines, the thermal stability was higher than for Pcs monomers. The stability of polymers increased with the average molecular weight.
|
| Keywords: |
organic semiconductors, phthalocyanine, polymers, electrical measurement, thermal stability.
|
| Year: |
2002
|
| Initial page: |
79
|
| Final page: |
87
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.81_2002.pdf |
|
|
| Author (s): |
Ion Ganescu, Vasilica Muresan, Liana Simona Sbirna, Anca Ganescu, Sebastian Sbirna, Dan Costel Preda
|
| Title: |
SPECTROPHOTOMETRIC STUDY ON THE FORMATION AND ANALYTICAL APPLICATION OF THE RHODIUM (III) CHELATE WITH 2-THIOXO-4-THIAZOLIDINONE |
| Abstract: |
The paper presents a spectrophotometric study of the binary system Rh(III)-2-thioxo-4-thiazolidinone. The formation conditions and the analyticalapplication of the formed complex for spectrophotometric determination of Rh(III) were studied. The composition of the Rh(III) chelate with this particular ligand was determined by the continuous variation method, its instability constant being Kinst = 1,61·10-8 mol2L-2.
|
| Keywords: |
rhodium (III), 2-thioxo-4-thiazolidinone, spectrophotometric study.
|
| Year: |
2002
|
| Initial page: |
89
|
| Final page: |
96
|
| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v10.n11.2002.90_2002.pdf |
|
|
