Multiphasic heterogeneous catalysis mediated by catalyst-philic liquid phases

Tundo, Pietro; Perosa, Alvise

doi:10.1039/b503021h

Cited by 91 publications

(82 citation statements)

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“…A number of such multiphase systems (homogeneous as well as heterogeneous) have been reviewed. 30,31,30,32 The present work is based on our long-standing experience of the engineering of multiphase systems composed of an organic solvent, water, and an IL, for cleaner catalytic procedures and (precious) catalyst recovery. 30,32,33 Under such (multiphase) conditions, phase separation and catalyst segregation are often made possible by common ionic liquids, including ammonium or phosphonium quaternary salts.…”

Section: ■ Introductionmentioning

confidence: 99%

Upgrade of Biomass-Derived Levulinic Acid via Ru/C-Catalyzed Hydrogenation to γ-Valerolactone in Aqueous–Organic–Ionic Liquids Multiphase Systems

Selva

Gottardo

Perosa

2012

ACS Sustainable Chem. Eng.

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A liquid triphase system made by an aqueous phase, an organic phase, and an ionic liquid was designed and applied to the catalytic hydrogenation/dehydration of biomass-derived levulinic acid to γ-valerolactone. This paper demonstrates that, by operating at 100−150°C and 35 atm of H 2 , both in the presence of Ru/C or of a homogeneous Ru precursor, the use of the triphase system designed to match the investigated reaction allows the following: (1) to obtain up to quantitative conversions and 100% selectivity toward the desired product; (2) to recover the product by simple phase separation; and (3) to preserve the catalyst activity for in situ recycles without loss of metal. Globally the investigated reaction proves the concept that a cradle-to-grave approach to the design of a catalytic reaction system can improve the global sustainability of a chemical transformation by improving efficiency, product isolation, and catalyst recycle.

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Section: ■ Introductionmentioning

confidence: 99%

Upgrade of Biomass-Derived Levulinic Acid via Ru/C-Catalyzed Hydrogenation to γ-Valerolactone in Aqueous–Organic–Ionic Liquids Multiphase Systems

Selva

Gottardo

Perosa

2012

ACS Sustainable Chem. Eng.

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“…The standard triphasic catalytic system was made by loading 1.0 ml of TOMAC, 9.0 ml isooctane, 0.10 ml 1-decanol and 2.0 ml KOH(aq) (20%) (for the Heck reaction the latter was substituted by 5.0 ml of 6% NaHCO 3 (aq)) in a three necked flask. To this were added 0.025 mmol of Pd(PPh 3 ) 4 , and the reaction stirred under air for 1 h until the middle phase turned completely black. The substrate was added (1.0 mmol 4-chloropropiophenone for HDX, or 1.0 mmol PhI and 1.5 mmol ethyl acrylate for the Heck reaction) and the reaction products monitored by GC-MS.…”

Section: ð2þmentioning

confidence: 99%

“…Recently, peculiar liquid systems formed by three separate liquid phases have attracted our attention, in particular with a view towards the possible effects on catalysis. 4 The interest was stimulated by knowledge of the formation of triphasic liquid systems made by mixtures of an organic solvent such as isooctane, water, and an onium salt (ammonium or phosphonium), and their use in heterogeneously catalysed organic reactions. 5 Increases in rates and selectivities could be achieved for a number of reactions catalysed, for example, by supported metals such as Pd, Pt, and by Raney-Ni.…”

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confidence: 99%

“…With the aim to generate and immobilize Pd-black in the third TOMAC phase, a suitable palladium precursor was sought, by testing PdCl 2 , Pd(OAc) 2 , Pd(PPh 3 ) 4 , and PdCl 2 (BzCN) 2 . Preliminary screening tests carried out with commercial A336 had indicated that Pd(PPh 3 ) 4 was the best precursor: it formed Pdblack which resided in the A336 phase.…”

mentioning

confidence: 99%

“…Preliminary screening tests carried out with commercial A336 had indicated that Pd(PPh 3 ) 4 was the best precursor: it formed Pdblack which resided in the A336 phase. The other complexes also formed Pd metal, in these cases however the particles were dispersed in more than one phase.…”

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Triphasic liquid systems: generation and segregation of catalytically active Pd nanoparticles in an ammonium-based catalyst-philic phase

et al. 2006

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A triphasic liquid system fabricated from isooctane, aqueous base, and trioctylmethylammonium chloride/decanol promoted the formation of Pd-nanoparticles in the size range of 2-4 nm which remained immobilised in the onium phase, catalysed organic reactions, and could be recycled.Onium salts, that are phase transfer agents, can be used to produce and stabilize metal nanoparticles (NPs) in situ, 1,2 and to control their size, 3 starting from appropriate precursors. Reetz and coworkers 2 have amply demonstrated that nanostructured R 4 N + X 2 -stabilized metal clusters can be prepared by a variety of methods. Recently, peculiar liquid systems formed by three separate liquid phases have attracted our attention, in particular with a view towards the possible effects on catalysis. 4 The interest was stimulated by knowledge of the formation of triphasic liquid systems made by mixtures of an organic solvent such as isooctane, water, and an onium salt (ammonium or phosphonium), and their use in heterogeneously catalysed organic reactions. 5 Increases in rates and selectivities could be achieved for a number of reactions catalysed, for example, by supported metals such as Pd, Pt, and by Raney-Ni. The onium salt was preferably liquid at the reaction temperature (20-50 uC), had a strong affinity for the catalyst, and formed a separate phase. The interaction between the liquid onium salt, and the catalyst was shown to be the factor controlling the improved catalytic effect. 6 In addition, the strong affinity of the onium salt for the catalyst made it a catalyst-philic phase, that simplified the separation of products from catalysts and from byproducts once the reaction was complete. 4 We reasoned that it would be interesting to take advantage of triphasic liquid systems, to generate, immobilise, and stabilise catalytically active metal NPs, starting from precursor metal complexes. The outcome was envisaged as shown in Fig. 1.This system offers a number of potential advantages in view of process intensification: (i) the active catalytic NPs can be prepared directly in the reactor, (ii) it is easy to separate the organic products from the catalyst by decanting, (iii) the catalyst morphology can be tuned, (iv) the metal NPs are stabilized by the third phase, and (v) inorganic reagents (i.e. base) and by-products remain in the aqueous phase, not to mention that the amount of catalyst-philic phase can be as small as convenient. All these issues are the basis for cleaner, cheaper catalytic systems, 7 and characterize some of the principles of green chemistry.This communication describes how a ternary system of this kind can be constructed, and used for catalytic reactions, through five subsequent steps: the preparation of a suitable ternary liquid system, formation of the active catalytic species, screening on a model organic reaction, catalyst recovery and recycle tests, and finally the characterisation of the active catalytic species by TEM.At first, the conditions for the reproducible formation of a model triphasic system wer...

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Phase Transfer Catalysis

Albanese

Penso

2020

Kirk-Othmer Encyclopedia of Chemical Technology

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Phase transfer catalysis (PTC) is a powerful tool to carry out organic reactions in a practical fashion, both in laboratory and industrial scale. Significant cost savings and major process improvements can be achieved in reactions performed in water–organic solvent mixtures under PTC conditions. Accordingly, the market of phase transfer catalysts has continuously grown in the past few years reaching 1000 USD Million size. Particularly advantageous is the possibility to replace expensive solvents and dangerous bases such as sodium hydride, requiring strictly anhydrous conditions, with aqueous bases and apolar, environmentally friendly, and easily recyclable solvents. During the last decade, notable results have been obtained in stereoselective reactions performed in the presence of chiral, non‐racemic quaternary ammonium salts. In addition, new avenues have been opened by the use of bulky chiral phosphate anions to generate lipophilic ion pairs enabling the stereoselective construction of important building blocks. Large scale industrial applications of asymmetric PTC have also been described.

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Multiphasic heterogeneous catalysis mediated by catalyst-philic liquid phases

Cited by 91 publications

References 91 publications

Upgrade of Biomass-Derived Levulinic Acid via Ru/C-Catalyzed Hydrogenation to γ-Valerolactone in Aqueous–Organic–Ionic Liquids Multiphase Systems

Upgrade of Biomass-Derived Levulinic Acid via Ru/C-Catalyzed Hydrogenation to γ-Valerolactone in Aqueous–Organic–Ionic Liquids Multiphase Systems

Triphasic liquid systems: generation and segregation of catalytically active Pd nanoparticles in an ammonium-based catalyst-philic phase

Phase Transfer Catalysis

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