Article ID Journal Published Year Pages File Type
67429 Journal of Molecular Catalysis A: Chemical 2008 4 Pages PDF
Abstract

Bisphosphineamine (PNP) ligands with various aryl substituents attached to the N atom of the ligand backbone were synthesized and tested together with Cr(acac)3 as ethylene tetramerization catalysts. Activated by methylaluminoxane, the best ligand with 3,5-dimethylphenyl attached to N atom achieved selectivity as high as 86.13% (1-octene and 1-hexene) and catalytic activity up to 4.98 × 106 g/mol Cr h toward 1-octene. It was established that the increase of m-substitution steric bulk in the aryl skeleton led to a dramatic increase of catalytic activity. Interestingly, with the increase of steric bulk in the o-substitution of the aryl ring, the catalytic activity declined and the selectivity of the catalyst changed from predominant tetramerization to trimerization. It was concluded that fine tuning of the N-aryl moiety of the PNP ligand in molecular structure is essential for obtaining efficient catalysis of ethylene tetramerization.

Graphical abstractA systematic study was conducted on the Cr catalyzed tetramerization of ethylene using bis(diphenylphosphino)amine ligands with N-aryl functionality. This study revealed that the oligomerization reaction product selectivity is primarily dependent on the structure and size of the N-aryl groups. Activated by methylaluminoxane, the best ligand with 3,5-dimethylphenyl attached to N atom achieved selectivity as high as 86.13% (1-octene and 1-hexene) and catalytic activity up to 4.98 × 106 g/mol Cr h. It was concluded that structural fine tuning of the N-aryl moiety of the PNP ligand is essential for obtaining efficient catalysts for ethylene tetramerization toward 1-octene.Figure optionsDownload full-size imageDownload as PowerPoint slide

Related Topics
Physical Sciences and Engineering Chemical Engineering Catalysis
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