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Please use this identifier to cite or link to this item: http://repositorio.ufba.br/ri/handle/ri/5999

Title: Ecofriendly ketalization of isatin using heteropolycompounds as catalysts
Authors: Santos, Edeilza Lopes dos
Gomes Jr, Walter Alves
Ribeiro, Núbia Moura
Andrade, Heloysa Martins Carvalho
Keywords: Keggin heteropolycompounds;Heteropolyphosphotungstic acid;Isatin;Ketalization
Issue Date: 2008
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.
Description: Acesso restrito: Texto completo. p. 18-23
URI: http://www.repositorio.ufba.br/ri/handle/ri/5999
ISSN: 1381-1169
Appears in Collections:Artigos Publicados em Periódicos (Quimica)

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