Synthesis and Evaluation of Trialkyl Ammonium Tetrakis(perfluorophenyl) Aluminate, a Highly Efficient Activator for High-Temperature Ethylene-α-Olefin Copolymerization Reactions

The new salt, [HNMe(C₁₈H₃₇)₂][Al(C₆F₅)₄], was prepared and was shown to be highly effective as an activator for Group IV precatalysts in high-temperature ethylene-1-octene copolymerization reactions. The performance of this activator closely mirrors that of the state-of-the-art activator borate-based analogue. Unlike the borate analogue, the aluminate activator reacts readily with water at ambient temperature, generating pentafluorobenzene, the only fluorine-containing product. Such a feature might be helpful when preparing polymers without any charged contaminants. Unlike some of the other aluminum compounds containing perfluorophenyl groups, [HNMe(C₁₈H₃₇)₂][Al(C₆F₅)₄] was found not to be impact-sensitive and is stable at ambient temperature for months. Detailed evaluation of this aluminate salt and several other aluminum alkyls/aryls (e.g., Al(C₆F₅)₃(THF), Al(C₆F₅)₃, AlEt₃, and MMAO-3A) was carried out to evaluate their reactive chemistry and safety profiles.