Ethylene polymerization under mild conditions using simple aluminum alkyls and chloro activators

Methylaluminum sesquichloride (Al2Cl3Me3, MAS), in the presence of ethyl trichloroacetate (ETAC), is found to be an effective catalyst for the production of polyethylene. Optimal catalyst productivities are obtained for a MAS:ETAC ratio of 1:1 at a reaction temperature of 75 degrees C. The polymerization is first order in both ethylene and MAS/ETAC concentration. NMR studies indicate that a 1:1 adduct is formed between binuclear MAS and ETAC, which is postulated to be a direct precursor to the active species. The productivity at elevated temperatures is limited by a radical decomposition process. Screening of various additives revealed that many halogenated organic reagents can act as activators, including carbon tetrachloride and p-toluene sulfonyl chloride. Improved productivities are obtained using sulfonyl chloride activators due to circumvention of radical decomposition pathways.