Propylene is a starting material for many important industrial processes and is classically derived as a side product of petroleum cracking; however, increased consumption is driving the development of on-demand methods like olefin metathesis. To access metathesis pathways to propene, we utilized W-H/Al2O3, which converts ethylene directly to propylene.[ii] However, this system suffers from catalyst deactivation, leading to low total yields of propylene.[iii] We then utilized the W-H/Al2O3 system to selectively produce propylene from various butene feeds. Cross-metathesis of ethylene and 2-butene was investigated and surprisingly, the W-H/Al2O3 catalyst is stable and highly selective to propylene even at substoichiometric ethylene ratios.[iv] Likewise, the autometathesis reactions of 1-butene and 2-butene have been studied and found to yield good selectivity to propylene, [v] unlike what should result from a classical Chauvin mechanism. Recently, we studied the cross-metathesis of isobutene and 2-butene to yield propene and 2-methyl-2-butene and found that the arrangement of substituents on the least thermodynamically favored tungstacyclobutane governs the conversion rate of the cross-metathesis reaction for propylene production from butenes and/or ethylene.[vi] Using computational methods we explored the reaction mechanism, concluding that the catalytic cycle involving ethylidene and methylidene is the most important in the reaction pathway.[vii] A) Mol, J. C. J. Mol. Catal. A: Chem. 2004, 213, 39– 45. B) Tullo, A. H. Chem. Eng. News 2003, 81, 15– 16. [ii] Taoufik, M.; Le Roux, E.; Thivolle-Cazat, J.; Basset, J. M. Angew. Chem., Int. Ed. 2007, 46, 7202– 7205. [iii] Mazoyer, E.; Szeto, K.C.; Merle, N.; Thivolle-Cazat, J.; Boyron, O.; Basset, J.-M.; Nicholas, C.P.; Taoufik, M. J. Mol. Catal. A 2014, 385, 125-32. [iv] Mazoyer, E.; Szeto, K.C.; Merle, N.; Norsic, S.; Boyron, O.; Basset, J.-M.; Taoufik, M.; Nicholas, C.P. J. Catal. 2013, 301, 1-7. [v] a) Mazoyer, E.; Szeto, K.C.; Norsic, S.; Garron, A.; Basset, J.-M.; Nicholas, C.P.; Taoufik, M. ACS Catal, 2011, 1, 1643-6. b) Mazoyer, E.; Szeto, K.C.; Basset, J.-M.; Nicholas, C.P.; Taoufik, M. Chem. Commun. 2012, 48, 3611-3. [vi] Szeto, K.C.; Mazoyer, E.; Merle, N.; Norsic, S.; Basset, J.-M.; Nicholas, C.P.; Taoufik, M. ACS Catal. 2013, 3, 2162-8. [vii] Motta, A.; Szeto, K.C.; Taoufik, M.; Nicholas, C.P. Catal. Sci. Technol. 2016, 6, 3386-93.

Metallacyclobutane structure influence on the production of propylene via olefin metathesis over surface organometallic chemistry derived catalysts

253rd National Meeting (2017)

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