Oxidative Alkenylation of Arenes Using Supported Rh Materials: Evidence that Active Catalysts are Formed by Rh Leaching

This work focuses on the synthesis of supported Rh materials and study of their efficacy as pre-catalysts for the oxidative alkenylation of arenes. Rhodium particles supported on silica (Rh/SiO2; similar to 3.6 wt% Rh) and on nitrogen-doped carbon (Rh/NC; similar to 1.0 wt% Rh) are synthesized and tested. Heating mixtures of Rh/SiO2 or Rh/NC with benzene and ethylene or alpha-olefins and CuX2 {X=OPiv (trimethylacetate) or OHex (2-ethyl hexanoate)} to 150 degrees C results in the production of alkenyl arenes. When using Rh/SiO2 or Rh/NC as catalyst precursor, the conversion of benzene and propylene or toluene and 1-pentene yields a ratio of anti-Markovnikov to Markovnikov products that is nearly identical to the same ratios as the molecular catalyst precursor [Rh(mu-OAc)(eta(2)-C2H4)(2)](2). These results and other observations are consistent with the formation of active catalysts by leaching of soluble Rh from the supported Rh materials.

Automated summary

This study focuses on the synthesis of supported Rh materials and their efficacy as pre-catalysts for the oxidative alkenylation of arenes. Results show that active catalysts are formed by leaching of soluble Rh from the supported Rh materials, leading to the production of alkenyl arenes with high selectivity.