Comparative study of new chromium-based catalysts for the selective tri- and tetramerization of ethyleneElectronic supplementary information (ESI) available: A detailed description of the experimental setup, the catalyst preparation, additional experimental results and crystallographic details for 2 are given in the ESI. CCDC 1032505. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4cy01441c

• Main Authors: Härzschel, Stefan, Kühn, Fritz E, Wöhl, Anina, Müller, Wolfgang, Al-Hazmi, Mohammed H, Alqahtani, Abdullah M, Müller, Bernd H, Peulecke, Normen, Rosenthal, Uwe
• Format: Article
• Language: English
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c4cy01441c

Two new ligands, Ph 2 PN(iPr)P(Ph)N( c -Hex)(CH 3 ) ( 2 ) (Ph = phenyl, iPr = isopropyl, c -Hex = cyclohexyl) and Ph 2 PN( c -Hex)P(Ph)NEt(CH 3 ) (Et = ethyl) ( 3 ) were synthesized. 2 was characterized by X-ray analysis. To compare their applicability with the previously known Ph 2 PN(iPr)P(Ph)N(iPr)H ( 1 ) these ligands were investigated together with chromium( iii )acetylacetonate, different co-catalysts and solvents for the catalytic oligomerization of ethylene. The in situ prepared catalysts proved to be highly active, yielding highly pure 1-octene as the main product and 1-hexene as the main byproduct. It was possible to reach productivities of several hundred kg product per gram chromium and hour, up to almost 65 wt% 1-octene with about 99% purity and overall 1-hexene plus 1-octene yields of more than 85 wt%. Small changes in ligand structure and conditions make a chromium ethylene oligomerization catalyst to switch from 1-hexene to 1-octene selectivity.