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Fluorous Solvent (fluorou + solvent)
Selected AbstractsFluorous Surface-Active Distannoxane CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Akihiro Orita Abstract Fluorous distannoxanes (XRf2SnOSnRf2X)2,n,H2O (Rf=C6F13C2H4) (1: X=C8F17SO3, n=10; 4: X=Cl, n=0) (1) catalyze the Mukaiyama aldol reaction and the allylation of aldehydes with tetraallyltin at room temperature in fluorous/organic biphasic solvent systems, in which the reactions proceed more rapidly than in a single organic or fluorous solvent. Due to the unique surface activity of 1, the catalyst, organic substrate(s), and reagent(s) are distributed in both organic and fluorous phases to facilitate smooth reactions. Upon dilution with toluene after the reaction, the catalyst concentrates to the fluorous phase, while the organic substances migrate to the organic phase to effect facile catalyst recovery and recycling. By virtue of such a unique solvophilicity, a new version of fluorous biphase technology has been developed. [source] Cobalt(II) octanoate and cobalt(II) perfluorooctanoate catalyzed atom transfer radical polymerization of styrene in toluene and fluorous media,A versatile route to catalyst recycling and oligomer formationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2005Marc-Stephan Weiser Abstract Cobalt(II) perfluorooctanoate-catalyzed atom transfer radical polymerization (ATRP) and reverse ATRP were developed to prepare oligostyrenes (Mn < 2500) with low polydispersities Mw/Mn < 1.5. Fluorous biphase catalysis was applied for effective recycling of catalyst and fluorous solvent. The homogeneous polymerization reaction was performed at 90 °C in toluene/cyclohexane/perfluorodecalin mixture (1:1:1) and fluorine-free solvents. Temperature-induced phase separation of this fluorous solvent mixture occurred at room temperature and proved to be the key for the very effective separation of the cobalt(II) perfluorooctanoate from the oligostyrene and fluorine-free solvents. Both the fluorine-tagged cobalt catalysts and the fluorous media were recycled and reused up to three times without encountering catalyst activity losses. The roles of cobalt catalysts, fluorous media, and monomer/initiator ratio were examined with respect to the polymerization kinetics. Fluorine-containing and fluorine-free cobalt(II) octanoate catalyzed controlled styrene oligomerization according to the ATRP mechanism. The molar mass control range was limited in fluorous biphase catalysis most likely because of precipitation of high molar mass polystyrenes in the fluorous reaction medium. To the best of our knowledge, this is the first time temperature-induced phase separation of fluorous and fluorine-free solvents has been successfully applied to polymerization processing. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3804,3813, 2005 [source] An Expedient Synthesis of Perfluorinated Tetraazamacrocycles: New Ligands for Copper-Catalyzed Oxidation under Fluorous Biphasic ConditionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2006Augustin de Castries Abstract Conjugate additions of cyclam to perfluorohexyl vinyl sulfone and sulfoxide, which act as efficient fluorous Michael acceptors, readily give access to new fluoro-ponytail tetraazamacrocycles in good yields. The solubility of the N -tetrasubstituted macrocycles depends dramatically on the nature of the polar function (SO or SO2): the sulfoxide cyclam derivative is soluble in perfluorodecaline (pfd) and perfluoromethylcyclohexane (pfmc) while the sulfonyl derivative is almost insoluble in organic or fluorous solvents. In agreement with the well known affinity of cyclam for copper(II) ions, stable copper complexes of the fluorous macrocyclic ligands have been isolated and characterized. In chloroform/methanol, complexes with four perfluorinated tails have been obtained from reaction of the tetra- N -perfluorohexylsulfinyl-substituted macrocycle with copper nitrate and copper perfluorocarboxylate. In trifluoroethanol, a selective retro-Michael reaction has been observed and the same reaction specifically gives copper complexes of the tri- N -substituted macrocycle. Complexes with three and four fluorous tails associated with perfluorocarboxylate counteranions are soluble in fluorous solvents (pfd and pfmc). These copper complexes were tested as catalysts for the oxidation of cyclohexene by molecular oxygen in the presence of tert -butyl hydroperoxide (tbhp). The oxidation reactions proceed under fluorous biphasic conditions and the catalyst can be recovered and reused. Quenching experiments indicate that cyclohexenyl hydroperoxide is the main oxidation product of the reaction performed with or without tbhp. Interestingly, these perfluorinated copper complexes are good, recyclable catalysts for the oxidation of cyclohexene by molecular oxygen without tbhp at room temperature and 65 °C.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Cover Picture: QSAR Comb.MOLECULAR INFORMATICS, Issue 8-9 2006Fluorous molecules are lipophobic and hydrophobic, they can be selectively separated by liquid-liquid extraction with fluorous solvents, solid-phase extraction and HPLC with fluorous silica gel. The cover picture highlights some representative structures of fluorous catalysts, reagents, scavengers, and protecting groups which have been developed for fluorous synthesis and reported in this special issue. [source] |