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metadata.dc.type: | Artigo de Periódico |
Title: | Ecofriendly ketalization of isatin using heteropolycompounds as catalysts |
Other Titles: | JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL |
Authors: | Santos, Edeilza Lopes dos Gomes Jr, Walter Alves Ribeiro, Núbia Moura Andrade, Heloysa Martins Carvalho |
metadata.dc.creator: | Santos, Edeilza Lopes dos Gomes Jr, Walter Alves Ribeiro, Núbia Moura Andrade, Heloysa Martins Carvalho |
Abstract: | The dioxolane ketals of isatin and 5-chloroisatin were prepared using an efficient and cleaner procedure than the usual synthetic routes. Keggin heteropolyacids, namely, heteropolyphosphotungstic acid (HPW), HPW/SiO2 and Cs2.2HPW, have proven to be useful catalysts, allowing to the fast, selective and solvent-less preparation of ketals, with high yields and 100% selectivity. The homogeneous HPW catalyst may be successfully heterogenized by partial exchange of H+ for Cs+ but some evidenceswere found of significant homogeneous contributions of leachedHPWwhen the silica supported catalysts (HPW/SiO2) was used in the ketalization reaction. The Cs2.2HPW (Cs2.2H0.8PW12O40) catalysts may be repeatedly used but a progressive activity losswas assigned to residual organic materials that could not be removed after several dichloromethane washings. |
Keywords: | Keggin heteropolycompounds Heteropolyphosphotungstic acid Isatin Ketalization |
URI: | http://www.repositorio.ufba.br/ri/handle/ri/5999 |
Issue Date: | 2008 |
Appears in Collections: | Artigo Publicado em Periódico (Química) |
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