Ícaro Sampaio Paulino

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.

Ethylene polymerization with zirconocene-MAO supported on molecular sieves

The catalytic activity of Cp2ZrCl2 supported on three types of molecular sieves (MCM-41, VPI-5 and Y Zeolites) was evaluated in the polymerization of ethylene. The supports were dehydrated, pre-treated with methylaluminoxane (MAO), and then reacted with Cp2ZrCl2. After heterogenization of Cp2ZrCl2 on the molecular sieves, the MAO concentration could be reduced without significant effect on the catalytic activity. The polymers obtained with the heterogeneous catalysts showed higher melting points and molecular weights, as well as narrower polydispersion than those obtained with the homogeneous catalyst precursor.

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%).

Cyclooctene epoxidation using Nb-MCM-41 synthesized at room temperature

Abstract An efficient and simple method for preparing Nb-MCM-41 has been developed. The mesoporous material Nb-MCM-41 was synthesized at room temperature using tetraethoxysilane (TEOS), tetramethylammonium hydroxide (TMAOH), cetyltrimethylammonium bromide (CTMABr) as template and NH 4 [NbO(C 2 O 4 ) 2 (H 2 O) 2 ].(H 2 O) 3 , as the niobium source. The materials were characterized by X-ray diffraction (XRD), FT-IR and diffuse reflectance UV-vis spectroscopies. The characterization showed that most of the niobium was incorporated into the framework of MCM-41. Nb-MCM-41 was tested in the epoxidation of cis-cyclooctene using t-butyl hydroperoxide as oxidant and a catalyst:cyclooctene molar ratio of 1:1000. The activity of Nb-MCM-41 increases with the temperature of the reaction. Cyclooctene oxide was obtained with 50% yield after 24 h at 333 K, without formation of any by-products.