Highly efficient homogeneous and heterogenized ruthenium catalysts for transfer hydrogenation of carbonyl compounds

Ganesamoorthy, S.; Jerome, P.; Shanmugasundaram, K.; Karvembu, Ramasamy

doi:10.1039/c4ra04136d

Cited by 22 publications

(9 citation statements)

References 36 publications

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“…In par with the literature, ketones substituted with electron withdrawing group yielded good conversion and selectivity. Usually, acetophenone bearing an electron donating group (EDG) is known to take a longer time frame to reach considerable conversion, [20] which forced us to test such substrates using the present protocol. The conversion of unsubstituted acetophenone was found to be better than that of those substituted with EDG (Table 3, entries 1–3), validating the negative effect of EDG.…”

Section: Resultsmentioning

confidence: 99%

“…The existing reports clearly revealed the importance of Pd‐catalyzed transfer hydrogenation reactions [16–18] . Further, complexes with CH 3 CN ancillary ligand have already been known as superior catalysts in many reactions [6,7,19–22] . These facts encouraged us to give special attention towards Pd pincer complexes bearing acetonitrile ancillary ligand for catalytic applications.…”

Section: Introductionmentioning

confidence: 99%

“…[16][17][18] Further, complexes with CH 3 CN ancillary ligand have already been known as superior catalysts in many reactions. [6,7,[19][20][21][22] These facts encouraged us to give special attention towards Pd pincer complexes bearing acetonitrile ancillary ligand for catalytic applications. In the present report, we discuss the results of our investigations on the use of Pd(II)-NNN pincer complexes as catalysts for TH of ketones.…”

Section: Introductionmentioning

confidence: 99%

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Pd(II)‐NNN Pincer Complexes for Catalyzing Transfer Hydrogenation of Ketones

et al. 2020

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Chiral and achiral Pd(II)-NNN pincer complexes (1-3) containing acetonitrile as an ancillary ligand were synthesized and characterized by spectroscopic (UV-visible, FT-IR, NMR and mass) techniques. Polarimetric experiments were employed to measure the specific rotation values of the chiral complexes {[α] D 27 = + 135°(2) and À 136°(3)}. The structures resolved through single crystal X-ray diffraction technique disclosed the distorted square planar geometry of the complexes. Transfer hydrogenation (TH) reactions of ketones were carried out in order to appraise the catalytic efficiency of the complexes. Remarkably, the TH results were promising for all the complexes, however, the chiral complexes (2 and 3) failed to induce chirality. Further probe led us to believe that the pincer complexes turned into Pd particles in situ and the later acted as an active catalyst. The scope of TH was extended to various substituted aromatic and heterocyclic ketones (Conversions = 75-99%).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pd(II)‐NNN Pincer Complexes for Catalyzing Transfer Hydrogenation of Ketones

et al. 2020

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“…The scope of the CuNPs/p(DMAEMA- co- TBA)/TSBA-catalyzed oxidation of various substituted alcohols was examined ( Table 1 ). The results indicate that aromatic alcohols usually require less reaction time and result in good conversion compared to aliphatic alcohols due to the good interaction between the aromatic alcohols and catalyst surface through π–π bonding [ 35 , 36 ]. The active oxidation of benzyl alcohol is due to the active phenyl group.…”

Section: Resultsmentioning

confidence: 99%

Dual Stimuli-Responsive Copper Nanoparticles Decorated SBA-15: A Highly Efficient Catalyst for the Oxidation of Alcohols in Water

et al. 2020

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In the present work, a temperature and pH-responsive hybrid catalytic system using copolymer-capped mesoporous silica particles with metal nanoparticles is proposed. The poly(2-(dimethylamino)ethyl methacrylate)(DMAEMA)-co-N-tert-butyl acrylamide) (TBA)) shell on mesoporous silica SBA-15 was obtained through free radical polymerization. Then, copper nanoparticles (CuNPs) decorated SBA-15/copolymer hybrid materials were synthesized using the NaBH4 reduction method. SBA-15 was functionalized with trimethoxylsilylpropyl methacrylate (TMSPM) and named TSBA. It was found that the CuNPs were uniformly dispersed in the mesoporous channels of SBA-15, and the hybrid catalyst exhibited excellent catalytic performance for the selective oxidation of different substituted benzyl alcohols in water using H2O2 as an oxidant at room temperature. The dual (temperature and pH-) responsive behaviors of the CuNPs/p(DMAEMA-co-TBA)/TSBA catalyst were investigated using the dynamic light scattering technique. The conversion of catalytic products and selectivity were calculated using gas chromatographic techniques, whereas the molecular structure of the products was identified using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The catalyst showed excellent catalytic activity toward the oxidation of alcohol to aldehyde in an aqueous medium below the lower critical solution temperature (LCST) and pKa values (7–7.5) of the copolymer. The main advantages of the hybrid catalyst, as compared to the existing catalysts, are outstanding alcohol conversion (up to 99%) for a short reaction time (1 h), small amount of the catalyst (5 mg), and good recyclability equal to at least five times.

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“…44 Based on Si materials, many newly synthesized (in addition to classic SiO 2 nanospheres) and characterized highly active systems have been reported in TH and ATH reactions (Schemes 6 and 7). [45][46][47][48] Silica-based polyoxometalate platforms, as organicinorganic hybrid silica-bonded catalysts having Ir and Rh metals, showed high catalytic activity and recyclability in the presence of isopropanol (IPA) or HCO 2 Na/H 2 O as the H source. [45][46][47] For the immobilization of presynthesized [Ru(acac) 2 (CH 3 CN) 2 ] (acac = acetylacetonate), a aminemodified SiO 2 complex was used; the resulting hybrid material was applied (88-99% isolated yield) and reused (90% yield after the sixth catalytic run) successfully in the transfer hydrogenation of substituted aryl/heteroaryl secondary alcohols (Schemes 6 and 7).…”

Section: Short Review Syn Thesismentioning

confidence: 99%

Selective Reduction of Carbonyl Compounds via (Asymmetric) Transfer Hydrogenation on Heterogeneous Catalysts

Baráth¹

2020

Synthesis

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Based on the ever-increasing demand for optically pure compounds, the development of efficient methods to produce such products is very important. Homogeneous asymmetric catalysis occupies a prominent position in the ranking of chemical transformations, with transition metals coordinated to chiral ligands being applied extensively for this purpose. However, heterogeneous catalysts have the ability to further extend the field of asymmetric transformations, because of their beneficial properties such as high stability, ease of separation and regeneration, and the possibility to apply them in continuous processes. The main challenge is to find potential synthetic routes that can provide a chemically and thermally stable heterogeneous catalyst having the necessary chiral information, whilst keeping the catalytic activity and enantioselectivity equally high (or even higher) than the corresponding homogeneous counterpart. Within this short review, the most relevant immobilization modes and preparative strategies depending on the support material used are summarized. From the reaction scope viewpoint, metal catalysts supported on the various solid materials studied in (asymmetric) transfer hydrogenation of carbonyl compounds are selected and represent the main focus of the second part of this overview.1 Introduction2 Synthesis of Chiral Heterogeneous Catalysts2.1 Immobilization of Homogeneous Asymmetric Catalysts2.1.1 Immobilization on Inorganic Supports2.1.2 Immobilization on Organic Polymers as Supports2.1.3 Immobilization on Dendrimer-Type Materials as Supports2.1.4 Self-Supported Chiral Catalysts: Coordination Polymers2.1.5 Immobilization Using Non-Conventional Media2.2 Chirally Modified Metal Surfaces for Heterogeneous Asymmetric Catalysis3 Examples of Transfer Hydrogenation on Heterogeneous Catalysts3.1 Silicon-Immobilized Catalysts3.2 Carbon-Material-Immobilized Catalysts3.3 Polymer-Immobilized Catalysts3.4 Magnetic-Nanoparticle-Immobilized Catalysts4 Conclusions

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Highly efficient homogeneous and heterogenized ruthenium catalysts for transfer hydrogenation of carbonyl compounds

Abstract: [Ru(acac)2(CH3CN)2] and its SiO2 immobilized form were found to be efficient catalysts for the transfer hydrogenation of carbonyl compounds.

Cited by 22 publications

References 36 publications

Pd(II)‐NNN Pincer Complexes for Catalyzing Transfer Hydrogenation of Ketones

Pd(II)‐NNN Pincer Complexes for Catalyzing Transfer Hydrogenation of Ketones

Dual Stimuli-Responsive Copper Nanoparticles Decorated SBA-15: A Highly Efficient Catalyst for the Oxidation of Alcohols in Water

Selective Reduction of Carbonyl Compounds via (Asymmetric) Transfer Hydrogenation on Heterogeneous Catalysts

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