Titanium Complexes with Functional Alkoxido Ligands for Selective Ethylene Dimerization - A High Throughput Experimentation Approach

摘要

New titanium complexes of general formula [Ti(OR)(2)(OiPr)(2)], containing functionalized alkoxido ligands, were developed for the selective catalytic dimerization of ethylene to 1-butene using a combined High Throughput Screening (HTS) / Design of Experiment (DoE) approach. First, a library of 19 ligands was elaborated and a primary screening spotted the phosphorus-functionalized alkoxido ligands as most promising. A second, more focused library containing 8 alkoxidophosphane ligands was then developed. A longer linear spacer between the alkoxido and the phosphorus functions, as in [Ti(19)(2)(OiPr)(2)], was found beneficial for this catalytic reaction. After identification of the best co-catalyst (AlEt3) and co-ligand (OnBu), final optimization of the reaction conditions was performed using a design of experiments (DoE) approach. The complex [Ti(19)(2)(OnBu)(2)] was shown to selectively dimerize ethylene in 1-butene (C-4(alpha)=93 % (99(+)%)) at 30 bar C2H4 and 55 degrees C with AlEt3 as co-catalyst, resulting in very high activity and selectivity for a molecular titanium catalyst (13000 g g(Ti)(-1) h(-1), 93 % 1-butene).