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Controllable Homogeneity/Heterogeneity Switch of Imidazolium Ionic Liquids for CO 2 Utilization
Author(s) -
Byun Jeehye,
Zhang Kai A. I.
Publication year - 2018
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201801086
Subject(s) - ionic liquid , cationic polymerization , catalysis , chemistry , cycloaddition , epoxide , substituent , nucleophile , reactivity (psychology) , isocyanate , combinatorial chemistry , chemical engineering , organic chemistry , medicine , alternative medicine , pathology , polyurethane , engineering
Imidazolium ionic liquids (IL) have been recognized as a promising platform for CO 2 capture and conversion owing to the structural designability through molecular combination of cationic substituents and counter anions. However, the conventional homogeneous catalysis with ILs accompanies a laborious work‐up procedure to recycle the catalyst and purify product after the reaction, limiting the applicability of ILs. Herein, we optimize the molecular structure of imidazolium ILs to mediate the cycloaddition of CO 2 upon epoxides, in which the IL functions as a homogeneous catalyst but exhibits heterogeneous separation capability. By varying the length of alkyl substituent on the imidazolium ring, the conversion efficiency of the epoxide into cyclic carbonate could be accelerated owing to higher reactivity of anions with longer aliphatic chains. The conversion efficiency was further optimized by having a proper type of counter anions with suitable level of nucleophilicity. The long‐chain IL exhibited temperature‐responsive phase transition behavior, allowing a facile isolation of IL and products after the reaction. In addition, with the high purity of obtained cyclic carbonates, non‐isocyanate poly(hydroxylurethane)s could be produced by polyaddition of diamines, promoting the utilization of CO 2 as a chemical building block.