Polar Phase Hydroformylation: The Dramatic Effect of Water on Mono- and Dirhodium Catalysts
The addition of 30% water (by volume) to acetone creates a remarkably effective polar phase solvent system for a dicationic dirhodium tetraphosphine hydroformylation catalyst. The initial turnover frequency (TOF) increases by 265% (to 73 min-1) for the hydroformylation of 1-hexene relative to the in...
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Published in | Journal of the American Chemical Society Vol. 125; no. 37; pp. 11180 - 11181 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
WASHINGTON
American Chemical Society
17.09.2003
Amer Chemical Soc |
Subjects | |
Online Access | Get full text |
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Summary: | The addition of 30% water (by volume) to acetone creates a remarkably effective polar phase solvent system for a dicationic dirhodium tetraphosphine hydroformylation catalyst. The initial turnover frequency (TOF) increases by 265% (to 73 min-1) for the hydroformylation of 1-hexene relative to the initial TOF in pure acetone (20 min-1). The aldehyde linear to branched (L:B) ratio increases to 33:1, and alkene isomerization and hydrogenation side reactions are essentially eliminated. Comparisons with monometallic rhodium catalysts based on PPh3, Bisbi, Naphos, and Xantphos ligands demonstrate that this polar-phase bimetallic catalyst is one of the fastest and most selective hydroformylation systems known under these mild conditions (90 °C, 6.2 bar H2/CO). The monometallic catalysts also show rate enhancements (although considerably smaller) in water−acetone, but Rh-Xantphos does show a large increase of 115%, with considerably reduced alkene isomerization side reactions. The dramatic effect of water on the dirhodium catalyst system is believed to be due to simple inhibition of the fragmentation of the catalytically active species into inactive mono- and bimetallic complexes. |
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Bibliography: | ark:/67375/TPS-6TQJZMCW-Z istex:0D63FD532DFDE0B76E58D8AAEE345235B8AADA86 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0002-7863 1520-5126 |
DOI: | 10.1021/ja035926w |