Fischer Indole Synthesis over Hydrous Zirconia-Supported Niobium Oxide

Liang Zhong; Gaik-Khuan Chuah

doi:10.1071/CH09237

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Fischer Indole Synthesis over Hydrous Zirconia-Supported Niobium Oxide

Liang Zhong ^A and Gaik-Khuan Chuah ^A ^B

+ Author Affiliations

- Author Affiliations

^A Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.

^B Corresponding author. Email: chmcgk@nus.edu.sg

Australian Journal of Chemistry 62(9) 1027-1033 https://doi.org/10.1071/CH09237
Submitted: 23 April 2009 Accepted: 15 June 2009 Published: 17 September 2009

Abstract

Supported niobium oxides are investigated as green catalysts for Fischer indole reaction. By means of wet impregnation, 10–40 wt-% Nb₂O₅ were loaded onto hydrous zirconia as a support. Pore size distribution curves showed that the niobium oxide overlayer was uniformly dispersed onto the mesoporous support. Samples with close to a monolayer coverage of niobium oxide had the highest activity in the Fischer indole reaction of phenylhydrazine with both 3-heptanone and cyclohexanone. A coverage higher than a monolayer led to lower activity. In comparison, the supported catalysts were more active than bulk niobium oxide or a sample prepared by co-precipitation of hydrous zirconia and niobium oxide.

Acknowledgements

Financial support from National University of Singapore under grant number R-143–000–329–112 is gratefully acknowledged.

References

Fischer Indole Synthesis over Hydrous Zirconia-Supported Niobium Oxide

Abstract

Acknowledgements

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