Anchored homogeneous catalysts: high turnover number applications

Augustine, Robert L.; Goel, Pradeep; Mahata, Nagendranath; Reyes, Clementine; Tanielyan, Setrak K.

doi:10.1016/j.molcata.2004.03.009

Cited by 40 publications

(36 citation statements)

References 18 publications

(22 reference statements)

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“…This was supported by ICP-MS data which indicated that at 60 8C very little Rh leaching occurs (i.e., [Rh] < 1 ppm) but that at 100 8C leaching became significant ([Rh] = 8.6 ppm). Although clearly less sensitive, 31 P NMR of selected samples collected at 60 8C showed no traces of phosphine present. (v) Neither DIOP nor BINAP were particularly successful ligands in terms of asymmetric hydrogenation (Entries 5-8), although DIOP gave much higher conversions than BINAP; this result is somewhat unexpected because both ligands perform successfully in conventional solvents.…”

Section: Resultsmentioning

confidence: 97%

“…The inactivity of BoPhoz is surprising since there are only relatively small structural differences between BoPhoz and Josiphos, and both ligands give good ee in the asymmetric hydrogenation of DMIT in conventional solvents such as ethanol. [31] It is therefore quite possible that the polarity of the solvent has an effect on the ee produced in the reactions.…”

Section: Resultsmentioning

confidence: 99%

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Continuous Asymmetric Hydrogenation in Supercritical Carbon Dioxide using an Immobilised Homogeneous Catalyst

et al. 2006

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Continuous flow supercritical carbon dioxide (scCO 2 ) has previously been shown (P. Stephenson, P. Licence, S. K. Ross, M. Poliakoff, Green Chem. 2004, 6, 521) to be a viable medium for conducting continuous asymmetric hydrogenation when it is combined with an appropriate enantioselective catalyst. Here we examine the use of a composite catalyst immobilisation system modified with several different types of asymmetric bisphosphine ligands in continuous flow scCO 2 . In particular, proprietary ligands from Solvias AG were found to be the most successful, with Josiphos 001 improving the enantiomeric excess (ee) to> 80 % in the asymmetric hydrogenation of dimethyl itaconate (DMIT); this ee is higher than that reported for the batch hydrogenation of DMIT using a homogeneous catalyst fully dissolved in scCO 2 (S. Lange, A. Brinkmann, P. Trautner, K. Woelk, J. Bargon, W. Leitner, Chirality 2000, 12, 450).

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Continuous Asymmetric Hydrogenation in Supercritical Carbon Dioxide using an Immobilised Homogeneous Catalyst

et al. 2006

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“…It must be mentioned that only a few results concerning the immobilization of the RhDuphos complex on carbon materials have been yet reported. They have been obtained by Augustine et al [17], using a heteropolyacid (particularly phosphotungstic acid) to promote the anchoring of the RhDuphos complex.…”

Section: Me-duphosrh(cod)]cl By Ionic Interactions With the Negativelmentioning

confidence: 99%

Non-covalent immobilization of RhDuphos on carbon nanotubes and carbon xerogels

Gheorghiu

Lecea

Román-Martı́nez

2014

Applied Catalysis A: General

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A c c e p t e d M a n u s c r i p t Research highlights The chiral catalyst RhDuphos has been anchored on carbon nanotubes and xerogels.  Non covalent anchoring strategies were used: electrostatic and - interactions.  Supports have been chemically modified to promote desired interactions.  RhDuphos on an oxidized carbon xerogel is active, enantioselective and reusable. The immobilization of the chiral complex RhDuphos, by electrostatic or π-π (adsorption) interactions, on carbon nanotubes and carbon xerogels is investigated. To promote such interactions, the supports were either oxidized or heat treated to create carboxylic type surface groups or an apolar surface, respectively. The catalysts were tested in the hydrogenation of methyl 2-acetamidoacrylate.The prepared hybrid catalysts are less active than the homogeneous RhDuphos, but most of them show a high enantioselectivity and the one prepared with the oxidized carbon xerogel is also reusable, being able to give a high substrate conversion, keeping as well a high enantioselectivity. The anchorage by electrostatic interactions is more interesting than the anchorage by - interactions, as the π-π adsorption method produces a modification of the metal complex structure leading to an active hybrid catalyst but without enantioselectivity.The creation of carboxylic groups on the support surface has led to some hindering of the complex leaching.

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“…These was proven when Dunnewijk et al [2] reported that homogeneous catalyst is not widely used in chemical industry because the catalyst is difficult to recover and the catalysts also suffer from corrosion problems and product contamination [2]. Moreover, the homogeneous metal catalyst such as palladium is expansive to afford, toxic and suffered from prohibited drawbacks deactivation of poor conversion [3] Therefore, due to these reason there is a need to use the most applicable catalyst which is heterogeneous catalyst where the metal is heterogenized on a polymer support [4]. Other than that, heterogeneous catalyst offered easy recovery of catalyst from the reaction mixture by simple filtration and can be reused for several times [5].…”

Section: Introductionmentioning

confidence: 99%

Immobilization of Highly Effective Palladium Catalyst Onto Poly(4-Vinylpyridine): Synthesis and Characterization

Soh¹,

Kassim²,

Jusoh

et al. 2016

MJAS

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A commonly known weakness of homogeneous catalysts is the difficulty to recover the active catalyst from the product. Due to the disadvantage, the designing of supported catalyst has been approached to overcome the separation difficulty of the palladium-based homogeneous catalyst. New polymer supported N 2 O 2 metal complex was successfully immobilized by mixing of poly(4-vinylpyridine) with palladium(II) complex in the presence of ethyl acetate as solvent. Then, the reaction was stirred for 72 hours at room temperature to form corresponding P 4 VP-Pd catalyst. The properties of immobilized catalyst were characterized by various techniques such as fourier transform infrared (FTIR), thermogravimetric (TGA), X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray (SEM/EDX) and inductively coupled plasma-optical emission (ICP-OES) spectroscopy. Keywords: immobilized catalyst, palladium(II) complex, poly(4-vinylpyridine)Abstrak Satu kelemahan penggunaan mangkin homogen adalah umum diketahui bahawa kesukaran untuk memperoleh kembali mangkin yang aktif daripada hasil produk. Oleh kerana kelemahan ini, reka bentuk mangkin berpenyokong telah diperkenalkan untuk mengatasi kesukaran pemisahan mangkin homogen berasaskan logam paladium. Kompleks logam N 2 O 2 berpenyokong polimer baru telah berjaya dipegunkan dengan mencampurkan poli(4-vinilpiridina) dengan kompleks paladium(II) dengan kehadiran etil asetat sebagai pelarut. Kemudian, campuran tindak balas dikacau selama 72 jam pada suhu bilik untuk menghasilkan mangkin P 4 VP-Pd. Sifat -sifat mangkin yang berjaya dipegunkan telah dicirikan dengan pelbagai teknik spektroskopi antaranya infra merah transformasi fourier (FTIR), analisis termogravimetrik (TGA), pembelauan sinar-X (XRD), mikroskopi elektron imbasan/ sinar-X tenaga tersebar (SEM/EDX) dan spektroskopi pancaran optik-aruhan (ICP-OES).

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Anchored homogeneous catalysts: high turnover number applications

Cited by 40 publications

References 18 publications

Continuous Asymmetric Hydrogenation in Supercritical Carbon Dioxide using an Immobilised Homogeneous Catalyst

Continuous Asymmetric Hydrogenation in Supercritical Carbon Dioxide using an Immobilised Homogeneous Catalyst

Non-covalent immobilization of RhDuphos on carbon nanotubes and carbon xerogels

Immobilization of Highly Effective Palladium Catalyst Onto Poly(4-Vinylpyridine): Synthesis and Characterization

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