Influence of elevated temperature and pressure on the chromium-catalysed tetramerisation of ethylene

摘要: A catalyst system comprising a diphenylphosphineamine (PNP) ligand, chromium(III) acetylacetonate and methylaluminoxane-based activator was studied for the selective tetramerisation of ethylene. The reaction investigated over broad temperature pressure range resulting product mixture interpreted in light recently published, enlarged metallacycle mechanism. Vapour-liquid equilibrium (VLE) data were calculated binary ethylene-cyclohexane relevant ranges to deconvolute influence ethylene concentration temperature. Good agreement experimental with proposed mechanism found. Enlargement metallacycloheptane ring by insertion found be dependent on concentration, albeit lesser extent than assumed. 1-octene selectivity, which reaches maximum 72–74 mass %, thus seems primarily formation cyclic side products methyl- methylenecyclopentane effect independent concentration. This is good accordance mechanism, since it indicates that occurs via rearrangement intermediate.