Recyclable Stereoselective Catalysts

Trindade, Alexandre; Góis, Pedro M. P.; Afonso, Carlos A. M.

doi:10.1021/cr800200t

Cited by 428 publications

(174 citation statements)

References 630 publications

(1,052 reference statements)

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“…[4] Metal complexes of Schiff bases were used as catalyst for the organic transformations such as oxidation [5], [6], olefin epoxidation [7], [8], polymerization of ethylene [9] even though homogeneous catalysts suffer from drawback of poor catalyst recovery and product separation [10]- [12]. However, it was found that the homogeneous Schiff base catalytic systems have two major disadvantages: 1) the lack of control of product, which causes the reactor fouling and 2) the limitation of its use in solution process.…”

Section: Introductionmentioning

confidence: 99%

Polymer Supported Schiff Base Iron Complex for Epoxidation of Trans-stilbene

Nath¹,

Pradhan²,

Maharana³

et al. 2017

IJCEA

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Abstract-In the present investigation, the novel recyclable polystyrene anchored iron complex supported by -ONN Schiff base is synthesized. This polymer anchored iron complex is prepared by the reactions of metal solution with one molar equivalent of polystrene supported Schiff-base ligands in methanol under nitrogen atmosphere. In contrast with other polymer-supported catalysts, the greatest advantage of this catalyst system was that the cost of the catalyst was remarkably low and recycled up to six times, due to the easily accessible materials and the simple synthetic route. The higher efficiency of complexation of metal ions on the polymer anchored Schiff base than unsupported analogue was another advantages of this catalyst system. The structural study reveal that iron(III) complex is octahedral in geometry.The catalytic activities of polystyrene supported iron complex toward the epoxidation of trans-Stilbene is investigated. Experimental results indicate that the reactivity of iron complex is dramatically affected by the polymer support and the rate of trans-Stilbene conversion was 4.27 × 10 -7 moledm -3 s -1 and obeys first order kinetics. The efficiency of supported catalysts remained almost constant upto six recycles.

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Section: Introductionmentioning

confidence: 99%

Polymer Supported Schiff Base Iron Complex for Epoxidation of Trans-stilbene

Nath¹,

Pradhan²,

Maharana³

et al. 2017

IJCEA

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“…[6][7][8][9][10][11][12][13] Serving as a new type of solvent for green technology are ionic liquids (ILs), which consist of ions such as quaternary ammonium or phosphonium ions and are liquids at room temperature. [14][15][16][17][18] Although the toxicity and biodegradability of ILs have not been sufficiently explored, they are known to be non-volatile and non-flammable. [14][15][16][17][18][19] Therefore, the use of ILs offers safety and environmental protection, as well as eliminates the problem of volatilization loss, which occurs with conventional organic solvents.…”

mentioning

confidence: 99%

“…[14][15][16][17][18] Although the toxicity and biodegradability of ILs have not been sufficiently explored, they are known to be non-volatile and non-flammable. [14][15][16][17][18][19] Therefore, the use of ILs offers safety and environmental protection, as well as eliminates the problem of volatilization loss, which occurs with conventional organic solvents. In addition, ILs have the ability to dissolve organic and inorganic compounds, while being immiscible with less polar solvent and water.…”

mentioning

confidence: 99%

Preparation of Chiral Ligands Connected with Quaternary Ammonium Group for Recyclable Catalytic Asymmetric Transfer Hydrogenation in Ionic Liquid

Uchimoto

Tsuji

Kawasaki

et al. 2015

CHEMICAL & PHARMACEUTICAL BULLETIN

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Reuse of chiral ruthenium catalyst in catalytic asymmetric transfer hydrogenation (CATH) has attracted attention from economic and environmental viewpoints, and reactions using ionic liquids (ILs) as solvent are recognized as one of the most useful methods for reuse of the catalyst. We synthesized (1S,2S)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine (TsDPEN) derivatives with various ionic moieties, and investigated the effect of their structure with respect to catalytic ability and recyclability in CATH with ILs. Ligand 3a having an imidazolium group showed the best results, and significant differences were observed depending on the structure of the ionic moiety or the length of the alkyl chain connecting the ligand site and the ionic moiety. Among various prochiral ketones used as substrates at various cycles, 3a showed a relatively good result.Key words ionic liquid; recyclable catalytic asymmetric hydrogenation; task-specific ligand; imidazolium salt Catalytic asymmetric transfer hydrogenation (CATH) is a very useful method for obtaining optically active secondary alcohols from prochiral ketones and for serving as an alternative to catalytic asymmetric hydrogenation with molecular hydrogen. CATH has many advantages in terms of safety and convenience over conventional hydrogenation because it uses 2-propanol or formic acid as a hydrogen source.1,2) Similar to catalytic asymmetric hydrogenation, CATH can also proceed with high catalytic efficiency and enantioselectivity by using a chiral transition metal complex. Especially well known as a catalyst is the ruthenium complex (1 and 2) with chiral N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine (TsDPEN) reported by Noyori and colleagues.3-5) CATH with the ruthenium catalyst has a high degree of applicability for synthetic chemistry in the laboratory as well as in industry. Several attempts to use CATH with recyclable catalysts have been reported with the aim of industrial application. The reuse of expensive transition metals such as ruthenium and the reduction of waste from reactions is advantageous from economic and environmental viewpoints. Indeed, transfer hydrogenation using polymer-or dendritic-supported TsDPEN ligand under heterogeneous conditions has been reported. [6][7][8][9][10][11][12][13] Serving as a new type of solvent for green technology are ionic liquids (ILs), which consist of ions such as quaternary ammonium or phosphonium ions and are liquids at room temperature.14-18) Although the toxicity and biodegradability of ILs have not been sufficiently explored, they are known to be non-volatile and non-flammable.14-19) Therefore, the use of ILs offers safety and environmental protection, as well as eliminates the problem of volatilization loss, which occurs with conventional organic solvents. In addition, ILs have the ability to dissolve organic and inorganic compounds, while being immiscible with less polar solvent and water. Organometallic complexes can work as homogeneous catalysts in ILs, and a simple extraction procedure can separate the p...

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“…[10] As far as we know, no asymmetric carbonyl-ene reaction of trifluoropyruvate in ionic liquid has been reported. [11] Considering the stability and recyclability of the In-A C H T U N G T R E N N U N G (III)-pybox complex in ionic liquid, [12] we attempted to carry out the ketone-ene reaction in ionic liquid.…”

mentioning

confidence: 99%