Biphasic fluorous media

Lanthanoid salts with non-coordinating anions carrying long perfluoroalkyl chains, Yb[C(SO2CgFi7)3[3 (19) and Sc[C(SO2CgFi7)3[3 (20), have been successfully used as Lewis catalysts for O-acylations, Friedel-Crafts, Diels-Alder, and Mu-kayama aldol reactions in fluorous biphasic media [21] (Scheme 3.6). In these reactions the fluorous medium avoids deactivation of the Lewis acid by solvent coordination. The catalyst can also be recycled and reused. 

Tetrakis(heptafluoropropyl)porphyrin (TPFPP) in a fluorous biphasic medium is effective for 02( Ag) generation and possesses good stability for... 

Another industrially important oxidation reaction, the Baeyer-Villiger oxidation [28] of ketones to esters by 35% aqueous hydrogen peroxide as oxidant, can also be advantageously conducted in a fluorous biphasic medium [29]. When the recyclable fluorous Letvis acidic tin(IV) complex (28) is used as catalyst very high selectivity of conversion of ketones to the corresponding esters or lactones is achieved (Scheme 3.11). 

Scheme 3.11 Baeyer-Villiger oxidation of ketones to the corresponding lactones. The oxidations were conducted in a fluorous biphasic medium in the presence of the fluorous tin(IV) complex 28 as Lewis acid catalyst. The selectivity is defined as the ratio of the quantity of lactone formed to that of ketone used [29].

Most of the other biphasic hydrogenations use also water as polar medium [130-145], Interesting variations are the use of aqueous micellar media [146] (see also Section 4.5) and the hydrogenation in aqueous media with Rh complexes which were deposited on aluminophosphate molecular sieves [147]. Other groups employed biphasic systems with fluorous solvents [148-151] or ionic liquids [152-153],... 

In conjunction with the work being done on fluorous biphasic systems, the development of fluorinated ligands has also made an impact in the area of supercritical carbon dioxide (SCCO2) catalysis. Supercritical CO2 has been heavily studied as a reaction medium for organometallic chemistry due to its unique properties. Its... 

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