Journal
CHEMISTRY-A EUROPEAN JOURNAL
Volume 13, Issue 19, Pages 5426-5432Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.200700010
Keywords
aldol reaction; hafnium; imines; Lewis acids; polyoxometalates
Categories
Ask authors/readers for more resources
Monolacunary polyoxotungstates [alpha(1)-P2W17O61](10-) and [alpha-PW11O39](7-) react with HfCl4 to yield [alpha(1)-HfP2W17O61](6-) and [alpha-Hf(OH)P-W11O39](4-), isolated as organo-soluble tetrabutylammonium (TBA) salts. Subsequent analyses, including mass spectrometry, show that they are stronger Lewis acids than (TBA)(5)H-2[alpha(1)-YbP2W17O61]. The new polyoxotungstates catalyze Lewis acid mediated organic reactions, such as Mukaiyama aldol and Mannich-type additions. In particular, reactions with aldehydes, which were impossible with lanthanide polyoxotungstates, are made possible. Thus these modifications of the polyoxometalate composition allowed fine tuning of the Lewis acidity. The catalysts could be easily recovered and reused.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available