Aurelia Pascariu

Academia Romana, Bucureşti, Hunedoara, Romania

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Publications (38)57.82 Total impact

  • Aurelia Pascariu · Smaranda Iliescu · Adriana Popa · Gheorghe Ilia
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    ABSTRACT: Phosphines are one of the most important classes of ligands in chemistry, in both the industrial and academic spheres. This review deals with the design and properties of polydentate phosphines, an original and broad class of multidentate ligands. The multidentate nature of these species has led to special properties, in which the spatial proximity of phosphorus atoms is crucial. The first part gives an overview of oligodentates polyphosphines in which is discussed the types and the basic routes for their synthesis. The review continues with the most important synthetic routes for obtaining complexes. Because of huge amount of literature data this review is not exhaustive, but it collects the most relevant findings in this area. The restriction to structural and spectroscopic properties allows us for a well organized handling of the complex material.
    No preview · Article · Dec 2009 · Journal of Organometallic Chemistry
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    ABSTRACT: The iminophosphorane CH2CH2[P{NP(O)(OPh)2}Ph2]2 is synthesized in high yields (80–97%) via a very convenient procedure using diphenylphosphoryl azide (DPPA) and 1,2-bis(diphenylphosphino)ethane.
    Full-text · Article · Oct 2009 · Tetrahedron Letters
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    ABSTRACT: Polyphosphonates, polyphosphates, polyarylazophosphonates and polyarylazophosphates were synthesized by a new alternative to the classical phase transfer catalysis, respectively, the modified inverse phase transfer catalysis (IPTC) polycondensation of various phenylphosphonic (phosphoric) dichlorides (phenylphosphonic dichloride, phenylphosphoric dichloride, p-chlorophenylphosphoric dichloride) with bisphenols: bisphenol A, tetrabromobisphenol A, bis-(4-hydroxyphenyl)methane (bisphenol F), 4,4′-dihydroxyazobenzene. The polymers were characterized by infrared spectroscopy and magnetic resonance (1H-NMR, 31P-NMR, 13C-NMR) spectroscopy. Yields in the range of 63.5–85% and molecular weights (M w) of ~2,000–8,200gmol−1 were obtained. Polyphosphonates were stable up 210–270°C and polyphosphates up 190–220°C in air atmosphere. For a correct estimation of the thermal behavior of similar compounds, a kinetic analysis using a modified version of Non Parametric Kinetic method for representative polyphosphonate and polyphosphate was realized. The studies made on the hydrolytic degradation of the synthesized polyphosphates show that the most stable polymer under alkali-catalyzed degradation is the polyphosphate obtained by IPTC of phenylphosphoric dichloride and bisphenol A.
    No preview · Article · Oct 2009 · Polymer Bulletin
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    ABSTRACT: The reaction of phenylphosphonic dichloride with bisphenol A (BA) by inverse phase transfer catalysis method was investigated. The design of experiments method was applied to establish the correlation between the simultaneous influence of the parameters (alkaline medium, reaction temperature, reagents molar ratio, and stirring speed) on yield and inherent viscosity, as well as for identifying the best reaction conditions. This method allows the simultaneous variation of control factors, thus decreasing the number of experiments in the polyphosphate synthesis. The process control factors used in this study were reagents' molar ratio, base concentration, and reaction temperature. The experimental results using 20 and 14 process runs, lead to an optimal synthesis procedure. The optimal values for yield and viscosity were obtained at molar ratio = 1, base concentration = 1.1 M, and reaction temperature = −12°C and have been experimentally verified with a series of four runs. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
    No preview · Article · Jul 2008 · Polymer Engineering and Science
  • A. Popa · V. Parvulescu · S. Iliescu · N. Plesu · G. Ilia · L. Macarie · A. Pascariu
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    ABSTRACT: The aminophosphonate styrene-divinylbenzene-silica hybrid materials are obtained in two step reactions: synthesis of alkoxysilane containing polymer precursors and preparation of organic/inorganic hybrid materials by sol-gel process. The prepared materials were characterised by infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy.
    No preview · Article · Jun 2008 · Plastics Rubber and Composites
  • L. Macarie · G. Ilia · S. Iliescu · A. Popa · N. Plesu · A. Pascariu
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    ABSTRACT: Ultraviolet (UV) curing is an important and widely used surface technology for coatings. The curable formulations containing: monomer: epoxydiacrylate, photoinitiating system: 4-methoxybenzoyldiphenylphosphine oxide/2-hydroxy-2-methyl-1-phenyl-propan-1-one, additive reactive: tertiary amine, and inorganic thermoresistant pigments: white (TiO2) and blue (Al2O3–Cr2O3), were cured like films by UV exposure. A series of experiments was carried out in order to optimise the photoinitiator ratios in photoinitiating system, and pigment content in the photocurable formulation. Films with enhanced mechanical properties (pendulum hardness, scratch resistance), high resistance at solvents and good appearance were developed. In order to provide adequate hiding power of the pigmented formulation, the pigment content has been chosen in the range 5–15%. Up to 15% pigment content may affect the efficiency of photoinitiator. The polymerisation efficiency (conversion and polymerisation rates) of photoinitiating systems in pigmented formulations was performed by differential scanning photocalorimetry (photo DSC) in comparison with the original systems without pigments.
    No preview · Article · May 2008 · Plastics Rubber and Composites
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    Aurelia Pascariu · Mircea Mracec · S.Berger
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    ABSTRACT: Dynamic NMR spectroscopy at very low temperatures (148–182 K) reveal the dynamic behavior of the (2-tri(3-furyl)-3-methyl-4-cyclopropenyl-oxaphosphetane) generated during a Wittig reaction between tri(3-furyl)ethylphosphonium iodine and cyclopropylaldehyde. The possibility of formation of different adducts between Li� ions and oxaphosphetane or betainic intermediates was checked calculating the formation enthalpies using the MNDO, AM1, and PM3 semiempirical MO methods. The observed species are interpreted as oxaphosphetane complexes with lithium ions present in solution. Quantum mechanical calculations confirm the spectroscopic results.
    Full-text · Article · Feb 2008 · International Journal of Quantum Chemistry
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    ABSTRACT: The synthesis of copolymers functionalized with phosphonate groups, incorporation of them into ordered meso-macroporous silica, characterization and evaluation of the obtained materials as catalysts in oxidation of cyclohexene are presented. The catalysts obtained are very active and selective in epoxidation of cyclohexene using hydrogen peroxide as an environmentally friendly oxidant.
    No preview · Article · Jan 2008 · Polymer Bulletin
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    ABSTRACT: Direct, efficient, organic solvent- and catalyst-free synthesis of a series of polyphosphates was accomplished. The reaction involved a gas-liquid interfacial poly-condensation between arylphosphoric dichlorides and bisphenol A. The polyphosphates were characterized by IR, H-1 NMR, P-31 NMR, inherent viscosity, thermal analysis, and molar mass. Yields in the range 70-90 % and inherent viscosities in the range 0.30-0.40 dl/g were obtained. The thermal stability of the polyphosphates was investigated by using thermogravimetry.
    Full-text · Article · Nov 2007 · Pure and Applied Chemistry
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    Maria Mracec · Aurelia Pascariu · Stefan Berger
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    ABSTRACT: For the Wittig reaction between butylidentriphenylphosphorane and benzaldehyde studied previously using NMR spectroscopy, three ionic intermediates have been proposed in order to explain the “stereochemical drift” (different ratio in oxaphosphetane stereoisomers compared with the ratio of the final Z/E olefins). In this paper, the PM3 semiempirical MO method was applied on the proposed ionic intermediates. Two of the ionic intermediates could lead to a shift of the reaction towards the final products, olefins and phosphine oxide, while the third intermediate could be implicated in a retro-Wittig reaction.
    Full-text · Article · Jul 2007 · International Journal of Quantum Chemistry
  • A. Popa · E. Avram · V. Cozan · A. Pascariu · V. Pârvulescu
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    ABSTRACT: The paper deals with the synthesis of aminophosphonate polymer-silice hibrid. In the first step chloromethylated polysulphone was chemically functionalized with aldehyde groups by direct oxidation with DMSO, followed by "one-pot" reaction of polysulphone aldehyde with diphosphite and (3-aminopropyl) trimethoxysilane.
    No preview · Article · Jan 2007 · MATERIALE PLASTICE
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    ABSTRACT: Fluorinated amines were phosphorilated in biphase systems using two methods: the liquid-liquid system using halogenated solvents or liquid-solid system using inorganic bases. The best results were obtained in liquid-solid system in the presence of potassium carbonate.
    No preview · Article · Dec 2006 · Revista de Chimie -Bucharest- Original Edition-
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    ABSTRACT: A novel synthesis of polyphosphates by inverse phase transfer catalysis (IPTC) was investigated. The reaction of methylphosphoric dichloride (MPD) and sodium salt of bisphenol A (BA) in two-phase H2O/CH2Cl2 medium under IPTC is presented and the results are evaluated by the yield and inherent viscosity values. The biphasic medium does not require rigorous stirring. The polyphosphate was characterized by IR, 1H NMR, 31P NMR, inherent viscosity, thermal analysis, and molar mass. Pyridine (Py), pyridine-oxide (PNO) and 4-dimethylamino-pyridine (DMAP) were used as the inverse phase transfer catalysts. DMAP was found to be the best catalyst.
    No preview · Article · Sep 2006 · Polymer
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    ABSTRACT: The electronic properties of 2-furyl and 3-furyl substituents attached to phosphanes and phosphonium salts were studied by means of IR spectroscopy and experimental and computational (31)P NMR spectroscopy. The heteroaromatic systems proved to be electron withdrawing with respect to phenyl substituents. However, phosphorus atoms with attached furyl substituents are strongly shielded in NMR. The reason for this phenomenon was studied by solid state (31)P MAS NMR experiments. The chemical shift tensor was extracted, and the orientation within the molecules was determined. The tensor component sigma(33), which is effected the most by furyl systems, is oriented perpendicular to the P-C bonds of the substituents. P-furyl bonds are shorter than P-phenyl bonds. We assume therefore a lower ground-state energy of the molecules, because of the electron withdrawing properties of the 2-furyl systems. The sigma(para) component of the (31)P NMR magnetic shielding is therefore smaller, which results in an overall increase of the magnetic shielding.
    Full-text · Article · Aug 2006 · Journal of the American Chemical Society
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    ABSTRACT: A styrene-divinylbenzene copolymer functionalized with aldehyde was prepared under phase transfer catalyzed (PTC) conditions. A statistical method for the calculation of the degree of functionalization with aldehyde groups is proposed. The degree of functionalization with aldehyde groups is relatively high. Styrene-divinylbenzene polymers functionalized with benzaldehyde groups were used in Wittig-Horner reaction, in order to introduce double bonds on polymers. The reactions were carried out using PTC method, solid-liquid-solid (s-l-s) (K2CO3, tetrahydrofuran, tetraethylammonium iodide) system. Phase transfer catalyzed reactions are often more easily and cheaply carried out than conventional method and they are therefore of particular interest.
    No preview · Article · May 2006 · Polymer Bulletin
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    ABSTRACT: In the paper some methods for the characterization of a series of arylazophosphonates compounds are presented. The studied compounds were obtained by the N-P coupling reaction of different diazotized aromatic amines, with dialkylphosphites. The obtained compounds were purified by HPLC, and were characterized by UV-VIS, IR, and NMR spectroscopy techniques. The results confirm the structure of the arylazophosphonates compounds.
    No preview · Article · Mar 2006
  • Nicoleta Plesu · Gheorghe Ilia · Aurelia Pascariu · Gabriela Vlase
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    ABSTRACT: Preparation and characterization of polyaniline (PANI) doped with anions containing phosphorus was investigated with the help of various technique. The chemical polymerization of aniline was carried out in acid media containing different anions of organic phosphorus acid with the use of ammonium peroxidisulfate as oxidant agent. The highest yield was observed in the case of styrilphosphonic acid. The conductivity increased in the following order: phenylphosphinic acid < 2chloroethylphosphonic acid < styrilphosphonic acid. The solubility tests carried out in DMF, DMSO and NMP showed that the presence of voluminous anions improves the solubility of doped PANI. The synthesized PANI was characterized by density, intrinsic viscosity, solubility, FTIR, UV–vis, NMR, conductivity and TGA measurements. The hardness, elasticity, resistance and protective behavior of acrylic films were determined. The acrylic dispersion based on PANI doped with anions containing phosphorus provides improved corrosion protection of carbon steel.
    No preview · Article · Feb 2006 · Synthetic Metals
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    ABSTRACT: Direct, efficient, solvent and catalyst-free synthesis of a series of polyphosphates was accomplished. The reaction involved a gas–liquid interfacial polycondensation between alkyl(aryl)phosphoric dichlorides and aromatic diols. The polyphosphates were characterized by IR, 1H NMR, inherent viscosity, thermal analysis, X-ray diffractions and molar mass. Yields in the range 75–90% and inherent viscosities in the range 0.24–0.45 dl g−1 were obtained. Polyphosphates were stable up to 170–250 °C, depending on phosphoric dichloride type. The X-ray diffraction patterns revealed that almost all the polymers were amorphous.
    No preview · Article · Jan 2006 · Green Chemistry
  • A. Popa · G. Ilia · A. Pascariu · S. Iliescu · N. Plesu
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    ABSTRACT: A chloromethylated styrene-divinylbenzene copolymer support system functionalized with 4-benzaldehyde and 2-benzaldehyde was prepared. The degree of functionalization with aldehyde groups is well suited for the subsequent use of the products as Wittig reagents. The polymer bound aldehyde was reacted with Wittig reagents to give olefm groups grafted on styrene-divinylbenzene copolymers. The reactions were carried out in phase transfer catalysis conditions. A simple procedure for the calculation of the degree of functionalization and the statistical modeling of the structural repetitive unit of the copolymer are reported.
    No preview · Article · Nov 2005 · Chinese Journal of Polymer Science (English Edition)
  • N. Pleşu · S. Iliescu · G. Ilia · A. Popa · A. Pascariu
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    ABSTRACT: The chemical polymerization of aniline was carried out in acid media containing different anions of phosphorous organic acids with the use of ammonium peroxidisulphate as oxidant agent. The highest yield was obtained in the case of stirylphosphonic acid. The conductivity increases in the order: phenylphosphinic acid 〈 2chloroethylphosphonic acid 〈 stirylphosphonic acid. The solubility tests carried out in DMF, DMSO and NMP showed that the presence of bulky anions improved the solubility of doped polyaniline. The polyaniline (PANI) was characterized by density, intrinsic viscosity, solubility, FTIR, UV-VIS, NMR, conductivity and TGA measurements.
    No preview · Article · Sep 2005 · Revue Roumaine de Chimie

Publication Stats

212 Citations
57.82 Total Impact Points

Institutions

  • 2002-2008
    • Academia Romana
      • • Institute of Chemistry Timisoara
      • • Department of Organic Chemistry
      Bucureşti, Hunedoara, Romania
  • 2005-2006
    • University of Leipzig
      • Institute of Analytical Chemistry
      Leipzig, Saxony, Germany