氟两相催化反应的进展

对氟两相催化反应作一介绍。氟两相体系是一种新的相分离和固定化技术,全氟溶剂与大多数有机溶剂不互溶,而在催化剂分子中引入适当数量、大小和形状的氟尾能使之优先溶于全氟溶剂,在氟两相体系中进行催化反应就使催化剂的回收再用产物的纯化都变得极为方便。     

Efficient condensation of carboxylic acids with alcohols catalyzed by fluorous ammonium triflates

The use of fluorous ammonium salts as metal-free catalysts for the direct condensation of equimolar amounts of carboxylic acids and aliphatic alcohols has been investigated. Esterification reactions were thus conveniently carried out under mild fluorous biphasic conditions, in the presence of 1 mol % of fluorous ammonium triflate and without recourse to any additional water removal technique. Good to excellent ester yields were obtained in the case of primary and secondary aliphatic alcohols. The fluorous salt was easily recovered by simple phase separation and reused at least three times without considerable loss of activity.     

Development of fluorous Lewis acid-catalyzed reactions

Organic synthetic methodology in the 21st century aims to conform to the principles of green sustainable chemistry (GSC) and we may expect that in the future, the realization of GSC will be an important objective for chemical industries. An important aim of synthetic organic chemistry is to implement waste-free and environmentally-benign industrial processes using Lewis acids as versatile as aluminum chloride. A key technological objective of our work in this area has been to achieve a "catalyst recycling system that utilizes the high activity and structural features of fluorous Lewis acid catalysts". Thus, we have developed a series of novel fluorous Lewis acid catalysts, namely the ytterbium(III), scandium(III), tin(IV) or hafnium(IV) bis(perfluoroalkanesulfonyl)amides or tris(perfluoro- alkanesulfonyl)methides. Our catalysts are recyclable and effective for acylations of alcohols and aromatics, Baeyer-Villiger reactions, direct esterifications and transesterifications in a fluorous biphasic system (FBS), in supercritical carbon dioxide and on fluorous silica gel supports.     

New fluorous/organic biphasic systems achieved by solvent tuning

Miscibility tests between 60 pairs of fluorous and organic solvents have been performed, and a number of biphasic systems based on hydrofluoroether solvents have been identified. Mutual solubilities of a series of fluorous and organic solvents have been measured to ascertain the compositions of the biphasic systems. A qualitative solvent tuning strategy based on solvent polarity and fluorophilicity/phobicity is introduced. Solvent tuning is then used to modulate the partition coefficients (P) of triarylphosphines with 0-3 fluorous tags. The results lay a foundation for future applications of these and related biphasic systems in catalysis and extraction.     

Performance of octene in fluorous biphasic hydroformylation: octene distribution and reversible transfer between perfluoromethylcyclohexane and nonanal

During fluorous biphasic hydroformylation 1-octene is transferred from the fluorous into the organic product phase and then from the product layer back to the fluorous layer again, due to the immiscibility of nonanal with PFMCH. The effect of the temperature and the total amount of octene on the above behaviour were also studied.     

Efficient, recoverable, copper-free Sonogashira reaction under FBS and thermomorphic mode

The solubility property of high fluorine content ligands allows us to report in this article the accomplishment under the fluorous biphasic system (FBS) the Pd-catalyzed Sonogashira reactions using novel recyclable Pd catalysts with fluorous-ponytails in the structure of 2,2′-bpy ligands that are only soluble in perfluorinated solvents at room temperature. Alternatively, without using any fluorous solvent but under the thermomorphic mode, the same Pd catalysts proceed with the Cu-free Sonogashira reactions homogeneously in DMF at 135 ± 5 °C, whereas the product mixtures after reaction remain in solution and the Pd catalysts precipitate from DMF at low temperature.     

Fluorous biphasic hydrolytic kinetic resolution of terminal epoxides

Although application of light-fluorous techniques facilitates the isolation of reaction products from the hydrolytic kinetic resolution (HKR) of terminal epoxides catalysed by cobalt complexes of salen ligands, the extension of the original fluorous biphasic approach to this reaction is far from being a trivial exercise. The nature of the counter anion has a dramatic effect on the catalytic activity of heavily fluorinated chiral (salen) cobalt(III) complexes. Excellent enantioselectivities are obtained in the fluorous biphasic HKR of 1,2-hexene oxide when fluorinated anions are introduced (e.e.s up to 99% both for the diol and the epoxide), with C₈F₁₇COO^- affording reaction rates even higher than those observed with non-fluorous systems.     

Polyfluorinated quaternary ammonium salts of polyoxometalate anions: fluorous biphasic oxidation catalysis with and without fluorous solvents

[reaction: see text] Polyfluorinated quaternary ammonium cations, [CF(3)(CF(2))(7)(CH(2))(3)](3)CH(3)N(+) (R(F)N(+)), were synthesized and used as countercations for the [WZnM(2)(H(2)O)(2)(ZnW(9)O(34))(2)](12)(-) (M = Mn(II), Zn(II)) polyoxometalate. The (R(F)N(+))(12)[WZnM(2)(H(2)O)(2)(ZnW(9)O(34))(2)] compounds were fluorous biphasic catalysts for alcohol and alkenol oxidation, and alkene epoxidation with aqueous hydrogen peroxide. Reaction protocols with or without a fluorous solvent were tested. The catalytic activity and selectivity was affected by both the hydrophobicity of the solvent and the substrate.     

Perfluoroalkylated-pyridine catalyzed Aldol condensations of aldehydes and ketones in a fluorous biphasic system without fluorous solvent

Aldol condensation of different ketones with various aromatic aldehydes proceeds efficiently in the presence of catalytic amount of perfluoroalkylated-pyridine in a fluorous biphasic system without fluorous solvent, which has prompted various concerns involving cost, solvent leaching, and environmental persistence. The catalyst can be recovered by simple cooling and precipitation and used again.     

金属络合物的相转移催化分析与分离

以可简单分离回收、可反复使用为目标，详细介绍了相转移催化的变化发展过 程．通过对溶剂的选择，使得催化剂选择性地溶解在某一液相中，而使产物溶解在 另一液相中，如水-有机两相催化体系；通过温度的变化，简单地实现了在较高温 度下反应为均相体系以提高催化剂的活性，而在较低温度下实现了催化剂与产物不 相溶使得催化剂得以简单分离，如温控型水-有机两相催化体系、氟-有机两相催化 体系、温控型含氟催化剂、温控型有机金属催化剂等．     

Fluorocarbon soluble copper(II) carboxylate complexes with nonfluoroponytailed nitrogen ligands as precatalysts for the oxidation of alkenols and alcohols under fluorous biphasic or thermomorphic modes: structural and mechanistic aspects

This fluorous biphasic catalysis (FBC) contribution was focused on the synthesis and characterization of new fluorous soluble R(f)-Cu(II) carboxylate complexes containing nonfluoroponytailed ligands and defines their role as precatalysts for the FBC oxidation of alkenols and alcohols in the presence of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO)/O(2). In this FBC approach, we have utilized the phase-switching technique of Vincent et al. (J. Am. Chem. Soc. 2002, 124, 12942) to solubilize the nonfluoroponytailed ligands, N-1,4,7-Me(3)TACN, 2, and N-1,4,7-pentamethyldiethylenetriamine (PMDETA), 3, by reaction with a fluorous solvent-soluble copper (II) dimeric complex, [Cu({C(8)F(17)(CH(2))(2)}(2)CHCO(2))(2)](2), 1. Moreover, the reaction of nonfluoroponytailed ligands 2 and 3 with 1 afforded new perfluoroheptane-soluble Cu(II) complexes, [Cu({C(8)F(17)(CH(2))(2)}(2)CHCO(2))(2)(2)], 4, and [Cu({C(8)F(17)(CH(2))(2)}(2)CHCO(2))(2) (3)], 5, respectively. The known Cu(II) complex, 1, was further characterized by electron paramagnetic resonance (EPR) spectroscopy confirming its dimeric structure, while 4 and 5 were characterized by elemental analysis, IR, diffuse reflectance UV-vis, and EPR spectroscopy. Furthermore, 1, 4, and 5 were evaluated as precatalysts for alkenol and alcohol oxidation. The oxidation reactions of alkenols and alcohols in the presence of TEMPO/O(2) proceeded under FBC conditions for 1, 4, and 5, but 1-octanol was unreactive under single-phase FBC conditions at 90 degrees C with TEMPO/O(2). The thermomorphic property of 5, soluble in chlorobenzene/toluene at 90 degrees C but insoluble at room temperature, was also evaluated in the selective oxidation of p-nitrobenzyl alcohol to p-nitrobenzaldehyde. Plausible mechanisms concerning these FBC/thermomorphic oxidation reactions will be discussed.     

A highly fluorous room-temperature ionic liquid exhibiting fluorous biphasic behavior and its use in catalyst recycling

[formula: see text] A novel fluorous room-temperature ionic liquid, 1-butyl-3-methyl-imidazolium tetrakis[p-[dimethyl(1H, 1H, 2H, 2H-perfluorooctyl)silyl]phenyl]-borate (1), was used as a solvent for the homogeneous hydrosilylation of 1-octene catalyzed by a fluorous version of Wilkinson's catalyst. The catalyst was recycled by biphasic separation with an average retention of catalyst activity of 94%. As opposed to other ionic liquids, 1 exhibits high miscibility with apolar compounds such as alkenes and resembles fluorous solvents in its phase behavior with organic solvents.     

A novel ytterbium/perfluoroalkylated-pyridine catalyst for Baylis-Hillman reaction in a fluorous biphasic system

Ytterbium perfluorooctanesulfonate [Yb(OPf)₃] catalyses the highly efficient Baylis-Hillman reaction in the presence of a catalytic amount of a novel perfluoroalkylated-pyridine as a ligand in a fluorous biphasic system (FBS) composed of toluene and perfluorodecalin. The new process can be carried out successfully without the use of a stoichiometric amount of Lewis base. The fluorous phase containing the active catalytic species is easily separated and can be reused several times without significant loss of catalytic activity.     

Maximising the efficiency of continuous photo-oxidation with singlet oxygen in supercritical CO2 by use of fluorous biphasic catalysis

Using a continuous fluorous biphasic separation, a photo-oxidation catalyst can be recycled, with increased productivity and a ×20 fold decrease in the amount of catalyst required.     

全氟辛基磺酰亚胺稀土(Ⅲ)催化氟两相Friedel-Crafts烷基化反应

制备了全氟辛基磺酰亚胺盐(M[N(SO2C8F17)2]n,n:3,4),并用于催化氟两相烷基化反应。考察了催化剂种类、反应时间、反应温度和催化剂用量对烷基化反应的影响,同时探讨了Yb[N(SO2C8F17)2]3对烷基化试剂摩尔比为0.2%时,催化烷基化试剂与不同芳烃的反应,表明Yb[N(SO2C8F17)2]3是一种有效的烷基化催化剂。含有催化剂的氟相通过简单的相分离后,可回收利用。氟相重复使用5次,其催化活性降低不大。     

Fluoroacrylate-bound fluorous-phase soluble hydrogenation catalysts

[reaction: see text] Fluoroacrylate polymer-bound hydrogenation catalysts are described. N-Acryloxysuccinimide-containing fluoroacrylate polymers were converted into phosphine ligands and subsequently into analogues of Wilkinson's catalyst by amidation of N-acryloxysuccinimide active ester residues and Rh exchange. The resulting catalysts have excellent activity and can be reused following fluorous biphasic liquid/liquid separation and extraction.     

Acid zeolites as alcohol racemization catalysts: screening and application in biphasic dynamic kinetic resolution

Acid zeolites were screened as heterogeneous catalysts for racemization of benzylic alcohols. The most promising zeolites appeared to be H-Beta zeolites, for which the optimal reaction conditions were studied in further detail. The zeolite performance was compared to that of homogeneous acids and acid resins under similar reaction conditions. In a second part of the research, H-Beta zeolites were applied in dynamic kinetic resolution (DKR) of 1-phenylethanol, which was conducted by means of a two-phase approach and which resulted in yields smoothly crossing the 50% border up to 90%, with an enantiomeric excess of >99%. To explore the applicability of this biphasic methodology, several other substrates were examined in the standard racemization reaction and in the biphasic dynamic kinetic resolution.     

Yb[N(SO2C8F17)2]3-catalyzed allylation of 1,3-dicarbonyl compounds with allylic alcohols in a fluorous biphase system

Allylation of 1,3-dicarbonyl compounds with allylic alcohols was successfully accomplished using rare earth metal (III) bis(perfluorooctanesulfonyl)imide [RE(NPf₂)₃, RE = La∼Lu] as catalysts in fluorous solvents. Ytterbium bis(perfluorooctanesulfonyl)imide [Yb(NPf₂)₃] catalyzes the high efficient reaction of allylation in fluorous solvents. By simple separation, fluorous phase containing only catalyst can be reused several times.     

Synthesis and properties of a novel family of fluorous triphenylphosphine derivatives

A novel approach to the preparation of perfluorotail-functionalized triarylphosphines using a p-silyl substituent as the branching point has been developed. This approach enabled the attachment of between three and nine perfluorotails per phosphorus atom, resulting in the production of highly fluorous tris[p-(1H,1H,2H, 2H-perfluoroalkylsilyl)aryl]phosphines, P[C(6)H(4)-p-SiMe(3)(-)(n)()(CH(2)CH(2)C(x)()F(2)(x)()(+1))(n)()](3) (n = 1, 2, 3; x = 6, 8), containing between 50 and 67 wt % fluorine. (31)P NMR studies indicate that the phosphorus atoms, and consequently the sigma-donor and pi-acceptor properties of these phosphines, are not influenced by the electron-withdrawing perfluoroalkyltails. The fluorous triarylphosphines are readily soluble in fluorous solvents and display fluorous phase preference in several fluorous biphasic systems. The phase partitioning of these fluorous ligands, as well as their donor properties, is discussed in relation to their potential for fluorous biphasic catalyst separation.     

A review of biphasic hydroformylation for long chain substrates

The regioselective hydroformylation reactions of long chain olefins catalyzed by different unmodified and modified Co-based, Rh-based catalysts are summarized. The mechanism of homogeneous hydroformylation reactions using Co-based/Rh-based catalysts (unmodified) showed inhibition of reaction rate due to higher partial pressure of CO and also caused difficulty in separating catalysts from the product mixture. Hydroformylation reactions in biphasic medium using water soluble catalysts (Rh, Co, Ru/TPPTS) with an effective surfactant, cetyltrimethylammonium bromide (CTAB), are discussed. The homogeneous biphasic systems are not applicable for long chain olefins due to their low solubility in aqueous phase.