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Simple and Effective Catalyst Separation by New CO 2 ‐Induced Switchable Organocatalysts
Author(s) -
Großeheilmann Julia,
Kragl Udo
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201700491
Subject(s) - catalysis , amine gas treating , chemistry , phase (matter) , aqueous solution , evaporation , nitroaldol reaction , solvent , aqueous two phase system , tertiary amine , organocatalysis , chemical engineering , organic chemistry , combinatorial chemistry , enantioselective synthesis , physics , engineering , thermodynamics
CO 2 ‐induced switchable tertiary amine‐based organocatalysts were investigated for an efficient catalyst and product separation by its different partitioning between an organic and carbonated water phase. In this case study, the switching ability of eight tertiary amine‐based catalysts between the organic and water phase by addition or removal of CO 2 was investigated. Here, the catalyst switched both nearly completely (99.9 %) into the aqueous phase by addition of CO 2 and effectively back into the organic phase (99.3 %) by expelling CO 2 . With this technique, the organocatalyst was successfully recovered and reused twelve times without significant loss of activity (up to 90 % enantiomeric excess) for the asymmetric nitroaldol (Henry) reaction. After the first catalyst switch, evaporation of the solvent affords the product in 98 % purity without any further purification steps.