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Oxidative Alkenylation of Arenes Using Supported Rh Materials: Evidence that Active Catalysts are Formed by Rh Leaching
Author(s) -
Luo Zhongwen,
Whitcomb Colby A.,
Kaylor Nicholas,
Zhang Yulu,
Zhang Sen,
Davis Robert J.,
Gunnoe T. Brent
Publication year - 2021
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.202001526
Subject(s) - rhodium , chemistry , catalysis , markovnikov's rule , benzene , leaching (pedology) , ethylene , toluene , organic chemistry , styrene , medicinal chemistry , nuclear chemistry , polymer chemistry , copolymer , regioselectivity , polymer , environmental science , soil science , soil water
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/SiO 2 ; ∼3.6 wt% Rh) and on nitrogen‐doped carbon (Rh/NC; ∼1.0 wt% Rh) are synthesized and tested. Heating mixtures of Rh/SiO 2 or Rh/NC with benzene and ethylene or α‐olefins and CuX 2 {X=OPiv (trimethylacetate) or OHex (2‐ethyl hexanoate)} to 150 °C results in the production of alkenyl arenes. When using Rh/SiO 2 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(μ‐OAc)( η 2 ‐C 2 H 4 ) 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.