On the 1,4-cis-Polymerization of Butadiene with the Highly Active Catalyst Systems Nd(C_3H_5)_2Cl·1.5 THF/Hexaisobutylaluminoxane (HIBAO), Nd(C_3H_5)Cl_2·2 THF/HIBAO and Nd(C_3H_5)Cl_2·2 THF/Methylaluminoxane(MAO) - Degree of Polymerization, Polyd

摘要

As we demonstrated previously, the allylneodymium compounds Nd(C_3H_5)_3·1,4-dioxane, Nd(C_3H_5)_2Cl·1.5 tetrahydrofuran (THF) and Nd(C_3H_5)Cl_2·2 THF form highly active catalyst systems for the industrially important 1,4-cis-polymerization of butadiene with Lewis acids, such as ethyl or diethyl aluminium chloride or methylaluminoxane (MAO). In contrast to the already extensively studied Ziegler-Natta-type catalysts, especially the industrially utilized ones based on neodymium carboxylate, the catalytically active species, namely the allylneodymium group, is completely preformed in the systems under investigation. For this reason the function of the cocatalyst during the formation of the active catalyst structure is limited to the coordinative interaction with the precatalyst and expected to allow its facile analysis, hence deepen understanding of the catalytic mechanism. In a previous paper we presented the investigation of catalyst systems consisting of Nd(C_3H_5)_3·1,4-dioxane and MAO and hexaisobutylaluminoxane (HIBAO), respectively. Here we describe a more exhaustive characterization of catalysts based on the allylneodymium chloride compounds Nd(C_3H_5)_2Cl·1.5 THF and Nd(C_3H_5)Cl_2·2 THF in combination with HIBAO and MAO, respectively.