Preparation Of Fluorous Lewis Acids And Their Application In Fluorous Biphasic Catalysis

The new phase-separation and immobilization technique known as fluorous biphase system (FBS) has become an active topic among researchers in both industry and academia. Fluorinated Lewis acids have stronger acidity than ordinary nonfluorinated ones, and well dissolved in perfluorinated organic solvents. Therefore, they can be used as effective, recyclable and environmental benign catalysts on many important synthetic reactions. Nowadays, fluorous biphase catalysis using fluorinated Lewis acids has attracted more and more interests.In this dissertation, two kinds of fluorinated Lewis acids such as metal perfluorooctanesulfonates[RE(OSO2Rf8)x, RE(OPf)x, RE=La-Lu, x=2,3] and metal bis(perfluorooctanesulfonyl)imide[RE[N(SO2Rf8)2]x, RE(NPf2)x, RE=Hf, Sc, La-Lu, x=3,4] were investigated. RE(OPf)x were prepared by heating the corresponding metal oxides, chlorides or carbonates in an aqueous perfluorooctane sulfonic acid (Rf8SO3H, PFOS) solution. RE(NPf2)x were prepared from the corresponding metal acetate or chlorides and bis(perfluorooctanesulfonyl)imide in an anhydrous organic solution. The obtained fluorinated catalysts were analyzed by TGA, IR, ICP and F-NMR.RE(OPf)x and RE(NPf2)x have the characteristic of stable, low hygroscopic and high fluorous affinity for FBS. Using various fluorous solvents and co-solvents, RE(OPf)3 were used as fluorous catalyst for such reactions:the oxide-cannizzaro reaction of a-methyl ketones, the synthesis of benzimidazoles, the synthesis of imidazoles and the Biginelli reaction. The perflate Pd(OPf)2 was active for Suzuki coupling in the coexistence of fluorous pyridine ligand. RE(NPf2)x (x=3,4) were used in the synthesis of quinolines and the allylation of 1,3-dicarbonyl compoundsThese fluorinated Lewis acids can be recovered easily after reactions and reused without significiant loss of activity.