Alessandra de Souza Maia

Synthesis and ethylene polymerization catalysis of mono(cyclopentadienyl)lanthanide compounds with the pyrazinamide ligand

In this work the synthesis of mono(cyclopentadienyl)lanthanide compounds containing methanesulfonate anion and pyrazinamide ligand is presented. The compounds were characterized by elemental analyses, complexometric titration with EDTA, thermal analyses, and vibrational spectra in the infrared region. In a preliminary catalytic study these compounds were active in ethylene polymerization when MAO was used as cocatalyst producing low crystalline polyethylene.

Synthesis, characterization and catalytic activity of some organolanthanides in ethylene polymerization

Abstract The synthesis and characterization of a new class of organolanthanide compounds containing the bromide and cyclopentadienyl anions together with a pyrazinamide ligand are presented. The compounds were characterized by elemental analyses, complexometric titration with EDTA, thermal analyses, vibrational spectra in the infrared region. The catalytic activity of these compounds in ethylene polymerization was examined.

Decomposição térmica do bicarbonato de sódio: do processo Solvay ao diagrama tipo Ellingham

A didactic experiment based on the thermal decomposition of sodium bicarbonate using a reagent found in the marketplace is proposed. The reaction products are identified by qualitative tests and stoichiometric calculations. The thermal stability of carbonates and the influence of lattice energies are discussed, emphasizing periodic trends in the alkali and alkaline earth families. The industrial importance of the reaction is also explored.

Synthesis and catalytic activity in ethylene polymerization of cyclopentadienylterbium dibromides with pyrazole or triphenylphosphine ligand

Abstract Organoterbium compounds TbBr2CpHPz and TbBr2CpPPh3 were obtained by reaction of pyrazole or triphenylphosphine ligands with cyclopentadienylterbium dibromide. These compounds were characterized by elemental analysis, complexometric titration with EDTA, thermal analysis, vibrational spectra in the infrared region and 1H NMR. In a preliminary catalytic study, these compounds were active in ethylene polymerization when MAO was used as cocatalyst, producing low crystalline polyethylene.

Compostos organolantanídeos contendo o ligante pirazinamida: síntese, caracterização e atividade catalítica na polimerização do etileno

In this work we report the synthesis of some organolanthanide compounds which were identified as LnCl2Cp(PzA)2, Ln = Nd, Sm, Eu and Tb, Cp = cyclopentadienyl and PzA = pirazinamide, by elemental analyses, complexometric titration with EDTA, thermal analyses and IR spectra. Thermal analysis and infrared spectra indicated that the coordination of the pyrazinamide to the lanthanide ions was made by the O atom of the carbonyl group and by one or both N atoms of the pyrazinamide ring. This class of compound showed catalytic activity of ca. 4.0 to 6.4 kgPE molLn-1 h-1 bar-1, in ethylene polymerization, using methylaluminoxane as cocatalyst. The resulting polyethylene presented low crystallinity (20%).

Synthesis and characterization of chlorovinylcyclopentadienyl lanthanides

Abstract In this work the synthesis and characterization of a novel class of organolanthanide compounds: [Ln(C 5 H 4 CHCH 2 ) 2 Cl], Ln=La, Sm, Eu, Gd, Dy, Er; [Ln(C 5 H 4 CHCH 2 )Cl 2 ], Ln=Nd, Tb and [Dy(C 5 H 4 CHCH 2 ) 3 ] are presented. Compounds were characterized by elemental analyses, complexometric titration with EDTA, argentimetric titration, thermal analyses, magnetic susceptibility and vibrational spectra in the infrared region. According to the infrared spectra, a σ-centered bonding is assumed, corresponding to a local symmetry C 5 v , for the vinylcyclopentadienyl anion.

Organolanthanide Compounds Containing Methanesulfonate and Pyrazinamide Ligand in Styrene Polymerization

Abstract The synthesis of organolanthanide compounds identified as LnCp* (MS)2PzA, Ln = Sm, Tb, Yb (MS = methanesulfonate, Cp* = pentamethylcyclopentadienyl, and PzA = pyrazinamide), by the reaction of coordination compounds Ln (MS)3(PzA)4 with NaCp in THF was reported. The complexes were formulated according to elemental analyses. complexometric titration with EDTA (%Ln), and 1H NMR. IR spectroscopy revealed that PzA coordinates with lanthanide (III) ions and methanesulfonate coordinates via oxygen atoms in a non-equivalent manner. In preliminary catalytic studies, these compounds were active in styrene polymerization that used MAO as a cocatalyst with an activity of 12.3 kg PS molSm−1h−1. Differential scanning calorimetry (DSC) of polystyrene showed that the polymer was mainly atactic.

Polimerização de estireno utilizando compostos organolantanídeos ativados por MAO

In an attempt to improve the performance of organolanthanide catalysts we investigated the use of the industrially important cocatalyst methylaluminoxane (MAO) to activate organolanthanide compounds in olefin polymerization. The catalytic systems LnBrCp2(THF)2/MAO (Cp=cyclopentadienyl) and LnBrCp*2THF/MAO (Cp*= pentamethylcyclopentadienyl), Ln=Pr and Yb, were active in styrene polymerization but inactive in ethylene and propylene polymerization. These systems produced atactic polystyrene with conversions of up to 8.2% (PrBrCp*2THF, Al/Ln=200, T=80oC, t=4 h) in toluene. In the absence of solvent, the conversion is 26.0% (1.5 h) and the molar mass of the atactic polystyrene is almost ten times higher (43 kg/mol).