Unparalleled dimerization of trans-2-butene to 3,4-dimethyl-1-hexene on iron-based catalyst

Trans-2-butene is regularly burned as a liquefied petroleum gas (LPG) component in several developing countries due to its inertness and inseparability in comparison to other butene isomers (1-butene and isobutene), resulting in low-value utilization of resource and environmental degradation. The generation of high-carbon olefins via trans-2-butene oligomerization has become one of the most effective ways for its high-value valorization. Octene is currently undersupplied via ethylene oligomerization, and its traditional crafts are costly due to separation from full-fraction α-olefins (C₄-C₃₀). In the present work, we synthesized a series of novel 2-phenyl-ketimine-1,10-phenanthroline iron complexes (Fe0-Fe9). Fe2 catalyst realizes the dimerization of trans-2-butene through homogeneous catalysis at moderate conditions (0.2 MPa, 30 °C), obtaining 3,4-dimethyl-1-hexene with 99.9 % selectivity. In contrast to the reported heterogeneous catalysts, our catalytic system exhibits a considerable improvement in activity and selectivity.