Catalytic Hydrodechlorination of Benzyl Chloride Promoted by Rh-N-heterocyclic Carbene Catalysts.

ChemSusChem

PubMedID: 25504980

Lázaro G, Polo V, Fernández-Alvarez FJ, García-Orduña P, Lahoz FJ, Iglesias M, Pérez-Torrente JJ, Oro LA. Catalytic Hydrodechlorination of Benzyl Chloride Promoted by Rh-N-heterocyclic Carbene Catalysts. ChemSusChem. 2014;.
The rhodium(I) complexes [Rh(Cl)(COD)(R-NHC-(CH2 )3 Si(OiPr)3 )] [COD=cyclooctadiene; R=2,6-diisopropylphenyl (1?a); n-butyl (1?b)] are effective catalyst precursors for the homogeneous hydrodechlorination of benzyl chloride using HSiEt3 as hydrogen source. This reaction is selective to the formation of toluene. However, in presence of a stoichiometric amount of potassium tert-butoxide (KtBuO) the formation of mixtures containing toluene together with 17-19 mol?% of the C?C homocoupling product, namely PhCH2 CH2 Ph, is observed. A mechanism proposal based on experimental insights and theoretical calculations at the DFT level that allows explanation of the experimental findings is included. Moreover, the heterogeneous catalytic system based on catalyst 1?a supported on MCM-41 has been demonstrated to be effective for the solvent-free hydrodechlorination of benzyl chloride using HSiEt3 and HSiMe(OSiMe3 )2 .