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A Brønsted‐Acidic Ionic Liquid Gel as an Efficient and Recyclable Heterogeneous Catalyst for the Synthesis of Bis(indolyl)methanes under Solvent‐Free Sonication
Author(s) -
Tran Phuong Hoang,
Nguyen XuanTrang Thi,
Chau DuyKhiem Nguyen
Publication year - 2018
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201700596
Subject(s) - ionic liquid , chemistry , catalysis , hydrogen sulfate , sulfonic acid , solvent , brønsted–lowry acid–base theory , organic chemistry , sonication , green chemistry , inorganic chemistry , chromatography
A Brønsted‐acidic ionic liquid gel was prepared from 1‐(4‐sulfonic acid)butyl‐3‐methylimidazolium hydrogen sulfate and tetraethoxysilane. Its structural characterization was accomplished by FTIR, TGA, SEM, EDS, and ICP‐OES. The ionic liquid gel promotes the synthesis of bis(indolyl)methanes. Interestingly, this catalyst allows the preparation of bis(indolyl)methanes in good to excellent yields within a short reaction time, through a clean and straightforward procedure. Moreover, the ionic liquid gel can be recovered by filtration and can be reused up to 5 times without any detectable loss of catalytic performance. Additionally, the method has a wide substrate scope and provides an accessible route for the large‐scale direct synthesis of bis(indolyl)methanes.