Artigo de Periódico
Spectroscopic and voltametric studies in titanium tris(pyrazolyl)borate catalysts
Fecha
2005Registro en:
1381-1169
v.238 n. 1-2
Autor
Simplício, Lílian M. T.
Rocha, Zênis N. da
Gil, Marcelo P.
Santos, João Henrique Zimnoch dos
Casagrande Junior, O. L.
Simplício, Lílian M. T.
Rocha, Zênis N. da
Gil, Marcelo P.
Santos, João Henrique Zimnoch dos
Casagrande Junior, O. L.
Institución
Resumen
The ethylene polymerization using TpMs*TiCl3 (1) (TpMs* = HB(3-mesitylpyrazolyl)2(5-mesitylpyrazolyl)−) and TpMsTiCl3 (2) (TpMs = HB(3-mesityl-pyrazolyl)3−) was performed in toluene or hexane at 60 °C in the presence of MAO or TiBA/MAO (1:1) as cocatalysts. Higher activities were found for the polymerization reactions carried out in hexane, and using a combination of TiBA/MAO as cocatalysts. Absorciometric measurements in the UV–vis region and cyclic voltammetric have shown that such complexes when activated by MAO were not stable. Measurements carried out in the presence 1-hexene have demonstrated the necessity to add the cocatalyst in the presence of an olefin, i.e., ethylene or hexene-1 in order to stabilize the active species. Furthermore, these studies have revealed that after the activation process most of Ti remains as TiIV.