Abstract
Quaternary ammonium geminal Brønsted acid ionic liquids (GBAILs) based on zwitterionic 1,2-bis[N-methyl-N-(3-sulfopropyl)-alkylammonium]ethane (where the carbon number of the alkyl chain is 4, 8, 10, 12, 14, 16, or 18) and p-toluenesulfonic acid monohydrate were synthesized. The catalytic ionic liquids were applied in three-component Mannich reactions with an aldehyde, ketone, and amine at 25 °C in water. The effects of the type and amount of catalyst and reaction time as well as the scope of the reaction were investigated. Results showed that GBAIL-C14 has excellent catalytic activity and fair reusability. The catalytic procedure was simple, and the catalyst could be recycled seven times via a simple separation process without noticeable decreases in catalytic activity.
Highlights
The Mannich reaction is one of the most important carbon–carbon bond-forming reactions in organic synthesis because of its atom economy and potential application in the synthesis of biologically active molecules [1,2,3]
Aniline, and cyclohexanone were chosen as model reactions to test the catalytic activities of geminal Brønsted acid ionic liquids (GBAILs)
We observed the GBAIL-C14-induced colloid via optical microscopy of the colloidal dispersions formed from GBAIL-C14 (5 mol %), benzaldehyde (1.0 mol), and aniline (1.0 mol) in water (1.5 mL) and found that spherical particles were formed (Figure 2)
Summary
The Mannich reaction is one of the most important carbon–carbon bond-forming reactions in organic synthesis because of its atom economy and potential application in the synthesis of biologically active molecules [1,2,3]. ILs have been referred to as “designer solvents” because their physical and chemical properties can be adjusted by varying the cation and anion These useful materials dissolve many organic and inorganic substances but are readily recycled. Other researchers have reported that the Mannich reaction could be conducted using Brønsted acid ILs as catalysts and solvents [23,24,25]. A major disadvantage in the use of an aqueous solvent is that most organic compounds are insoluble in water To circumvent this disadvantage, surfactant-type catalysts [30,31], which solubilize organic materials or form micellar dispersions, have been utilized. Novel quaternary ammonium geminal Brønsted acid ionic liquids (GBAILs) were synthesized (see Scheme 1) and applied to catalyze three-component Mannich reactions in water.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
