title: Simple and Effective Catalyst Separation by New CO2-Induced Switchable Organocatalysts.
abstract: CO2-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 CO2was investigated. Here, the catalyst switched both nearly completely (99.9 %) into the aqueous phase by addition of CO2and effectively back into the organic phase (99.3 %) by expelling CO2. 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.
authors.affiliation: Department of Chemistry, University of Rostock, Albert-Einstein-Str. 3a, 18059, Rostock, Germany.
authors.forename: Julia
authors.identifier: 0000-0003-1646-4507
authors.initials: J
authors.lastname: Großeheilmann
authors.affiliation: Department of Chemistry, University of Rostock, Albert-Einstein-Str. 3a, 18059, Rostock, Germany.
authors.forename: Udo
authors.identifier: 0000-0002-2507-7472
authors.initials: U
authors.lastname: Kragl
mesh_terms: D000588:Amines / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry* / Q000302:isolation & purification*; D002384:Catalysis; D003035:Cobalt / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry; D012997:Solvents / Q000737:chemistry
chemical_list: D000588:Amines; D009930:Organic Chemicals; D009942:Organometallic Compounds; D012997:Solvents; D002245:Carbon Dioxide; D003035:Cobalt; D012238:Rhodium
keywords: biphasic; catalyst recycling; downstream processing; organocatalysis; switchable catalysts