Liquids in Multiphasic Reactions

Multiphasic Reactions General Features, Scope and Limitations 

It is important to make the distinction between the multiphasic catalysis concept and transfer-assisted organometaUic reactions or phase tranfer catalysis (PTC). In this latter approach, a catalytic amount of quaternary ammonium salt (Q] (X] is present in an aqueous phase. The catalyst lipophUic cation [Q] transports the reactant s anion Y to the organic phase, as an ion-pair, and the chemical reaction occurs in the organic phase of the organic/aqueous two-phase mixture [2]. 

Since then, water has emerged as a usefiil solvent for organometallic catalysis. In addition to the hydroformylation reactions, several other industrial processes employing homogeneous catalysis have been converted to aqueous-phase procedures [4]. 

---

Ionic Liquids in Multiphasic Reactions 271 Turnover frequency [(mol of aldehydes produced)(mole Rh) (min) ]... 

Certainly, the use of heterogenized (homogeneous) catalysts is not the only important field of industrial catalyst research. There are many other possibilities, which enable the easy separation of catalysts after the reaction has been performed. Some present concepts with (potential) industrial applicability are the use of fluorous biphasic systems [ 125,126], of ionic liquids [ 127-129] and ionic liquids in multiphasic reactions [130-132] and heterogeneous multifunctional reaction systems (simultaneous appUcation of two or more sup-... 

Olivier-Bourbigou H, Forestiere A (2003) Ionic liquids in multiphasic reactions. In Wasserscheid P,Welton T (eds) Ionic liquids in synthesis. Wiley-VCH,Weinheim,p 258 Wasserscheid P (2003) Multiphasic catalysis with ionic liquids in combination with compressed COj. In Wasserscheid P, Welton T (eds) Ionic liquids in synthesis. Wiley-VCH,Weinheim,p 281 Keim W (2003) Green Chem 5 105... 

Olivier-Bourbigou H, Forestiere A (2003) Ionic liquids in multiphasic reactions. In Wasserscheid P, Welton T (eds) Ionic liquids in synthesis. Wiley, Weinheim, pp 258-280... 

---