Water-based reactions immobilized ligands

Typical approaches to this biphasic system have involved the immobilization of catalysts in the aqueous phase as colloids [53] or using water-soluble catalysts based on ligands such as the trisulfonated TPPTS [55, 56]. Particularly high reaction rates have been obtained with surfactant-stabilized microemulsions and emulsions that allow for intimate contact of all reagents with the catalyst during the reaction [57]. The emulsions separate readily into two phases by small pressure changes and the C02-phase is then vented to isolate the products. The catalyst RhCl(tppds)3 (tppds =... 

Imidazolium-styrene copolymers were prepared by copolymerization of 1-vi-nyl-3-butylimidazolinm-based ionic liquids ([VBImJX, X=C1 , BF ", and PFg) with styrene, which were used as polymeric supports to immobilize Pd(OAc)2 using a method of alcohol reduction [22]. It was demonstrated that Pd existed in the form of Pd nanoparticles (NPs) on these imidazolium-styrene copolymers. Using the [VBIm]Cl-styiene copolymer as a support, Pd NPs of less than 6 nm were formed, which was particularly interesting, as usually only a Pd carbene complex was formed when Pd(OAc)2 was treated with 1,3-dialkyimidazolium ionic liquids containing a halide anion. The copolymer-supported Pd catalysts were found to be efficient and reusable catalysts for the Heck reaction in water in the absence of a phosphine ligand and phase-transfer catalyst. 

---