Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups in supercritical carbon dioxide: selective control and mechanism |
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| Authors: | Zhao-Yang Wang Huan-Feng Jiang Xiao-Yue Ouyang Shao-Rong Yang |
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| Affiliation: | a College of Chemistry, South China University of Technology, Guangzhou 510640, PR China
b Department of Chemistry, South China Normal University, Guangzhou 510006, PR China |
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| Abstract: | Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups was carried out smoothly in supercritical carbon dioxide under oxygen atmosphere when polystyrene-supported benzoquinone (PS-BQ) or CuII (CuI) chloride was employed as cocatalyst. The higher selectivity was achieved, without any chlorinated by-product detected, when using PS-BQ instead of CuII (or CuI) chloride. PS-BQ could be recycled with excellent catalytic activity remaining after each simple filtration. Chlorine ion was demonstrated to be a promoter. The different acetalization mechanisms were revealed by the subtle relationship of chlorine ion and benzoquinone (BQ) to the catalytic activity of PdCl2/PS-BQ, PdII-CuCl2 or Pd(OAc)2/PS-BQ. |
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| Keywords: | Acetalization Benzoquinone Palladium Supercritical carbon dioxide Wacker oxidation |
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