Abstract
We present the first unambiguous evidence of the interfacial mechanism of phase-transfer catalysis (PTC) by direct observation of the formation of carbanions in the interfacial region between the aqueous and the organic phase by using a surface-sensitive spectroscopic method known as second harmonic generation (SHG). Ion exchange of carbanions adsorbed at the surface after addition of lipophilic tetraalkylammonium salts (TAA) to organic phase and transport of the lipophilic ion-pairs to the organic phase is observed. Results allow for the formulation of a more detailed mechanism of PTC.
Highlights
Phase-transfer catalysis (PTC) is a general methodology for organic reactions that proceed between anionic species and non-charged lipophilic partners.[1]
Continuously transfer inorganic anions from the aqueous into the organic phase in which further reactions take place, and the interfacial mechanism proposed by Makosza for reactions of carbanions,[1a,b] in which the key step is deprotonation of the carbanion precursors in the interfacial region with the aqueous sodium hydroxide
We report first direct observation of carbanions generated at the interface between organic solvents and aqueous solutions of strong bases, in particular 50 % NaOH(aq.), using a surface sensitive spectroscopic method, second harmonic generation (SHG)
Summary
Phase-transfer catalysis (PTC) is a general methodology for organic reactions that proceed between anionic species and non-charged lipophilic partners.[1]. The subsequent ion exchange with the TAA salts in the interfacial region produces lipophilic ion pairs that migrate into the organic phase where further reactions take place.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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.
