How do physical-chemical parameters influence the catalytic hydrogenation of 1,3-cyclohexadiene in ionic liquids?

Paul S Campbell; Ajda Podgorsek; Thibaut Gutel; Catherine C Santini; Agílio A H Pádua; Margarida F Costa Gomes; François Bayard; Bernard Fenet; Yves Chauvin

doi:10.1021/jp102941n

How do physical-chemical parameters influence the catalytic hydrogenation of 1,3-cyclohexadiene in ionic liquids?

J Phys Chem B. 2010 Jun 24;114(24):8156-65. doi: 10.1021/jp102941n.

Authors

Paul S Campbell¹, Ajda Podgorsek, Thibaut Gutel, Catherine C Santini, Agílio A H Pádua, Margarida F Costa Gomes, François Bayard, Bernard Fenet, Yves Chauvin

Affiliation

¹ Université de Lyon Institut de Chimie de Lyon, UMR 5265 CNRS-Université de Lyon 1-ESCPE Lyon, C2P2, Equipe Chimie Organometallique de Surface, ESCPE 43 Boulevard du 11 Novembre 1918, F-69616 Villeurbanne, France.

PMID: 20504005
DOI: 10.1021/jp102941n

Abstract

The catalytic hydrogenation of 1,3-cyclohexadiene using [Rh(COD)(PPh(3))(2)]NTf(2) (COD = 1,5-cyclooctadiene) was performed in two ionic liquids: 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(1)C(4)Im][NTf(2)], and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, [C(1)C(1)C(4)Im][NTf(2)]. It is observed that the reaction is twice as fast in [C(1)C(4)Im][NTf(2)] than in [C(1)C(1)C(4)Im][NTf(2)]. To explain the difference in reactivity, molecular interactions and the microscopic structure of ionic liquid +1,3-cyclohexadiene mixtures were studied by NMR and titration calorimetry experiments, and by molecular simulation in the liquid phase. Diffusivity and viscosity measurements allowed the characterization of mass transport in the reaction media. We could conclude that the diffusivity of 1,3-cyclohexadiene is 1.9 times higher in [C(1)C(4)Im][NTf(2)] than in [C(1)C(1)C(4)Im][NTf(2)] and that this difference could explain the lower reactivity observed in [C(1)C(1)C(4)Im][NTf(2)].