Hydroformylation Of Olefins Research Articles

Modular Synthesis of Phosphite and Phosphoramidite Ligands for Rh‐Catalyzed Hydroformylation

AbstractRhodium‐catalyzed hydroformylation of olefins is an important method for synthesizing aldehydes, and it is worth noting that regioselectivity and enantioselectivity of the product controlled by ligand are the most commonly used strategies. The modular synthesis of phosphite and phosphoramidite ligands have significant advantages of simple synthesis and high catalytic activity, which was why these ligands have been widely used in hydroformylation reactions. Herein, we focus on the synthesis methods and design ideas of such ligands, as well as their application effects in hydroformylation reactions. This review aims to provide a reference for the design and synthesis of ligands in hydroformylation subsequently.

Sulfur Poisoning and Self-Recovery of Single-Site Rh1 /Porous Organic Polymer Catalysts for Olefin Hydroformylation.

Sulfur poisoning and regeneration are global challenges for metal catalysts even at the ppm level. The sulfur poisoning of single-metal-site catalysts and their regeneration is worthy of further study. Herein, sulfur poisoning and self-recovery are first presented on an industrialized single-Rh-site catalyst (Rh1 /POPs). A decreased turnover frequency of Rh1 /POPs from 4317 h-1 to 318 h-1 was observed in a 1000 ppm H2 S co-feed for ethylene hydroformylation, but it self-recovered to 4527 h-1 after withdrawal of H2 S, whereas the rhodium nanoparticles demonstrated poor activity and self-recovery ability. H2 S reduced the charge density of the single Rh atom and lowered its Gibbs free energy with the formation of inactive (SH)Rh(CO)(PPh3 -frame)2 , which could be regenerated to active HRh(CO)(PPh3 -frame)2 after withdrawing H2 S. The mechanism and the sulfur-related structure-activity relationship were highlighted. This work provides an understanding of heterogeneous ethylene hydroformylation and sulfur-poisoned regeneration in the science of single-atom catalysts.

Sulfur Poisoning and Self‐Recovery of Single‐Site Rh1/Porous Organic Polymer Catalysts for Olefin Hydroformylation

AbstractSulfur poisoning and regeneration are global challenges for metal catalysts even at the ppm level. The sulfur poisoning of single‐metal‐site catalysts and their regeneration is worthy of further study. Herein, sulfur poisoning and self‐recovery are first presented on an industrialized single‐Rh‐site catalyst (Rh1/POPs). A decreased turnover frequency of Rh1/POPs from 4317 h−1 to 318 h−1 was observed in a 1000 ppm H2S co‐feed for ethylene hydroformylation, but it self‐recovered to 4527 h−1 after withdrawal of H2S, whereas the rhodium nanoparticles demonstrated poor activity and self‐recovery ability. H2S reduced the charge density of the single Rh atom and lowered its Gibbs free energy with the formation of inactive (SH)Rh(CO)(PPh3‐frame)2, which could be regenerated to active HRh(CO)(PPh3‐frame)2 after withdrawing H2S. The mechanism and the sulfur‐related structure–activity relationship were highlighted. This work provides an understanding of heterogeneous ethylene hydroformylation and sulfur‐poisoned regeneration in the science of single‐atom catalysts.

Rhodium nanoparticles supported on silanol-rich zeolites beyond the homogeneous Wilkinson’s catalyst for hydroformylation of olefins

Hydroformylation is one of the largest industrially homogeneous processes that strongly relies on catalysts with phosphine ligands such as the Wilkinson’s catalyst (triphenylphosphine coordinated Rh). Heterogeneous catalysts for olefin hydroformylation are highly desired but suffer from poor activity compared with homogeneous catalysts. Herein, we demonstrate that rhodium nanoparticles supported on siliceous MFI zeolite with abundant silanol nests are very active for hydroformylation, giving a turnover frequency as high as ~50,000 h−1 that even outperforms the classical Wilkinson’s catalyst. Mechanism study reveals that the siliceous zeolite with silanol nests could efficiently enrich olefin molecules to adjacent rhodium nanoparticles, enhancing the hydroformylation reaction.

Hydroformylation of Lower Olefins and the Use of Oxo Synthesis Products Based on C4–C5 Aldehydes in the Production of Ester Lubricating Oils. Part 1. Catalysts and Industrial Processes

Hydroformylation of Lower Olefins and the Use of Oxo Synthesis Products Based on C4–C5 Aldehydes in the Production of Ester Lubricating Oils. Part 1. Catalysts and Industrial Processes

Hydroformylation of Alkenes over Phosphorous-Free Rhodium Supported on N-Doped Silica

A new phosphorous-free rhodium supported on a nitrogen-doped silica was successfully used as a catalyst for the hydroformylation of alkenes. The obtained material and the catalyst were characterized by XRD, XPS, FTIR, SEM, TEM, ICP AES, and low-temperature nitrogen adsorption–desorption measurements. The catalytic performance was studied by the example of the hydroformylation of octene-1 at temperatures of 80–140 °C and a pressure of 5.0 MPa. The catalyst provided a 99% conversion of 1-octene with a 98% yield of aldehydes and showed a good conversion of styrene and cyclohexene. The catalyst can be repeatedly used in ten consecutive cycles, with its activity remaining constant.

Interplay between Catalyst Complexes and Dormant States: In Situ Spectroscopic Investigations on a Catalyst System for Alkene Hydroformylation

Results from a detailed in situ IR and NMR spectroscopic study on a monophosphite-modified rhodium catalyst system are presented. Equilibria that occur between the catalytically active hydrido rhodium(I) complexes and formally inactive dinuclear rhodium(0) complexes as well as mononuclear ortho-metalated rhodium(I) complexes have been investigated. The latter can be considered as “dormant states”, which are formed at conditions with lower hydrogen pressures or [H2]/[Rh] ratios. It was found that dimer formation is dominant at lower temperatures and higher rhodium concentrations, whereas ligand metalation is effective at higher temperatures. At the appropriate partial pressure of hydrogen, the regeneration of hydrido rhodium(I) complexes takes place on a short time scale from both states. Especially, the temporary stabilization of the catalyst via ligand metalation during a catalyst recycling procedure represents a feasible approach.

Heterogenized Molecular Rhodium Phosphine Catalysts within Metal–Organic Frameworks for Alkene Hydroformylation

Heterogenized Molecular Rhodium Phosphine Catalysts within Metal–Organic Frameworks for Alkene Hydroformylation

Promotion effects of FeCu co-doping on Co3O4-based catalysts for linear α-olefins to alcohols

For the preparation of alcohols from linear α-olefins, Cu or/and Fe doped Co3O4 catalysts were synthesized using two processes and their structural and catalytic properties were studied. Using microwave-assisted and hydrothermal (HT) crystallization processes, doped Co3O4 with the rod-like morphology and the lamellar morphology were obtained, respectively, and the two morphology both showed the dominantly exposed Co3O4 (111) and (220) planes which were related to the successive hydroformylation and hydrogenation steps of olefins. With microwave-assisted process, Cu doped Co3O4 dramatically improved the hydroformylation reactivity of 1-octene. FeCu or NiCu co-doped Co3O4 raised nonanol selectivity and the promotion of FeCu co-doping was better. At 150 °C and 7 MPa for 4 h reaction, 2Fe2Cu-Co3O4(nFe:nCu:nCo = 2:2:100) exhibited 1-octene conversion of 99.82% and nonanol selectivity of 50.80%. With HT crystallization process, 2Fe2Cu-Co3O4-HT displayed 1-octene conversion of 99.69% and nonanol selectivity of 67.87% under 150 °C, 7 MPa for 5 h reaction. The effects of reaction temperature, pressure, time and catalyst dosage on the activity were discussed. At the set reaction conditions, 2Fe2Cu-Co3O4-HT exhibited high activity for C6 ∼ C12 olefins converting to C7 ∼ C13 alcohols. The roles of Cu or/and Fe doping and the effects of the exposed crystal planes of Co3O4 were revealed by characterizations.

Iodide-Assisted Pd Catalysis as an Attractive Alternative to Rh Catalysis for the Industrially Relevant Isoselective Hydroformylation of Simple Aliphatic Alkenes

AbstractThe hydroformylation of simple aliphatic alkenes, such as propylene, is one of the largest homogenous catalyzed processes in the chemical industry, producing over 10 million metric tons of different aldehydes each year. Typically, such processes are catalyzed by Co or Rh catalysts, yielding mostly linear aldehydes, such as n-butanal. However, the increasing demand for branched aldehydes, such as isobutanal, triggered further investigation to develop efficient isoselective protocols, which remain scarce. In this Synpacts article, we discuss our recent work on iodide-assisted Pd catalysis as an attractive alternative strategy for the development of isoselective methods. This article is presented considering the state of the art for Rh-catalyzed processes. Additionally, we discuss the limitations and challenges that need to be addressed in order to successfully transfer the technology to industry.1 Introduction2 State of the Art for the Isoselective Rh-Catalyzed Hydroformylation of Unbiased Aliphatic Alkenes2.1 Decomposition-Driven Isoselectivity2.2 Substrate-Dependent Isoselectivity2.3 Equiselective Catalysis2.4 Isoselective Rh Catalysts Bearing Small-Bite-Angle Ligands2.5 Isoselective Rh Catalyst Bearing a Tridentate Ligand2.6 Isoselective Catalysis Driven by Rh Encapsulation2.7 Isoselective Catalysis Driven by Specific Noncovalent Substrate–Ligand Interactions3 Pd-Catalyzed Isoselective Hydroformylation of Unbiased Aliphatic Alkenes3.1 Selectivity Patterns in Pd-Catalyzed Hydroformylation of Alkenes3.2 Unusual Iodide-Assisted Binuclear Pd(I)–Pd(I) Mechanism3.3 Development of Pd-Catalyzed Isoselective Hydroformylation of Unbiased Aliphatic Alkenes4 Conclusions and Outlook

Understanding Rh‐catalysed Hydroformylation with Phosphite Ligands through Catalyst Speciation Analysis by Operando FlowNMR Spectroscopy

AbstractPhosphites are industrially important ligands for the Rh‐catalysed hydroformylation of olefins because they produce more active catalysts than phosphines, which is mainly due to their strong π‐acceptor properties facilitating CO dissociation from the metal centre. Herein, the effect of three prominent phosphite ligands (triphenylphosphite, Alkanox and BiPhePhos) on catalyst speciation during turnover is investigated using multi‐nuclear operando FlowNMR spectroscopy. The quantitative catalyst distribution maps derived explain activity trends across a range of catalytic reaction conditions that show how phosphites produce more active catalysts, including reduced formation of inactive Rh0 dimers in the absence of substrate during pre‐activation and at the end of the reaction. Additionally, [(alkanox)Rh(acac)] complexes have been found to be of high stability which can be exploited for post‐catalytic Rh recovery by simple addition of 2,4‐pentanediones.

Iron‐Catalyzed Magnesium‐Mediated Formal Hydroformylation of Alkynes and Alkenes

AbstractAlkynes and alkenes are routinely converted to corresponding synthetically versatile aldehydes using rhodium‐catalyzed hydroformylation. However, rhodium is rare, precious, costly, and depleting at a considerably high rate. Reported here is iron‐catalyzed, magnesium‐mediated, formal hydroformylation of alkynes and alkenes in the absence of syngas. Readily available FeCl2 in the presence of alkyl magnesium halide, and dimethyl formamide, catalyzes hydroformylation of various alkynes and selectively produces α,β‐unsaturated aldehydes in good to excellent conversion. Mechanistic investigations revealed the presence of vinyl magnesium intermediate, the kinetic study disclosed the first‐order dependence of the reaction on iron loading, and the control experiment authenticated the iron catalyst‘s homogeneous nature. The scope of this methodology was amplified, and 20 alkenes were examined. [Fe(acac)3] in the presence of ligand, alkyl magnesium halide, and dimethyl formamide catalyzed the hydroformylation of alkenes and displayed good to excellent conversion. An earth‐abundant iron catalyst offering a syngas cylinder‐free safe alternative to high‐pressure hydroformylation has been reported.

A diphosphoramidite ligand for hydroformylation of various olefins.

A new rotationally hindered diphosphoramidite ligand has been applied to the Rh-catalyzed hydroformylation of various olefins. Good activity as well as excellent regioselectivity toward the formation of linear aldehydes were achieved. Remarkable performances were also observed in the hydroformylation of functionalized olefins, including methyl acrylate, allyl acetate, crotonaldehyde ethylene acetal and styrene.

Enhancing stability via confining Rh-P species in ZIF-8 for hydroformylation of 1-octene.

The stability of Rh-based heterogeneous catalysts is a key issue in the hydroformylation of olefins. Confinement of active Rh species has been considered an effective strategy to achieve stable catalysts. In this work, a phosphine ligand was successfully confined in ZIF-8 material and coordinated with Rh metal by a reduction procedure to develop an efficient and stable Rh-based catalyst for hydroformylation of 1-octene. The results indicate that the catalyst reduced at 300°C under H2atmosphere exhibits better stability than that with NaBH4as reductant and undoped P catalyst. Various characterization studies demonstrate that the superior performance is due to the strong interaction between Rh metal and P, which inhibits the leaching of active Rh species. This work reveals an effective strategy for the synthesis of highly stable catalysts for use in the hydroformylation reaction.

Coupling rules for bifunctional pair sites

Bifunctional catalysts containing metals and metal oxides are used to promote industrial processes such as alkene hydroformylation. The finding that pair site bifunctional catalysts improve the efficiencies and selectivities of reactions provides principles for the design of new types of catalysts.

Formyl Radical Generation from α‐Chloro N‐Methoxyphthalimides Enables Selective Aldehyde Synthesis

AbstractThe aldehydes installation by radical formylation constitutes an attractive synthetic strategy. However, the generation of formyl radicals for organic synthesis applications remains unknown. Herein we report the first formyl radical generation from α‐chloro N‐methoxyphthalimides, which selectively synthesize aldehydes by alkene hydroformylation under mild photoredox conditions. The aldehydes can be installed on acrylates, acrylamides, vinyl sulfones, vinyl ketones, and complex steroids by radical hydroformylation in excellent chemoselectivity and regioselectivity. The concerted hydrochloride elimination for the formyl radical generation from α‐chloro methoxy radicals is established by experimental and computational approaches.

Formyl Radical Generation from α-Chloro N-Methoxyphthalimides Enables Selective Aldehyde Synthesis.

The aldehydes installation by radical formylation constitutes an attractive synthetic strategy. However, the generation of formyl radicals for organic synthesis applications remains unknown. Herein we report the first formyl radical generation from α-chloro N-methoxyphthalimides, which selectively synthesize aldehydes by alkene hydroformylation under mild photoredox conditions. The aldehydes can be installed on acrylates, acrylamides, vinyl sulfones, vinyl ketones, and complex steroids by radical hydroformylation in excellent chemoselectivity and regioselectivity. The concerted hydrochloride elimination for the formyl radical generation from α-chloro methoxy radicals is established by experimental and computational approaches.

Fabrication of the Microenvironment and Active Structure of Single-Rh-Site Catalysts for Efficient Hydroformylation of Olefins

Fabrication of the Microenvironment and Active Structure of Single-Rh-Site Catalysts for Efficient Hydroformylation of Olefins

Highly Active Rh Catalysts with Strong π-Acceptor Phosphine-Containing Porous Organic Polymers for Alkene Hydroformylation.

Phosphine-containing porous organic polymers (phosphine-POPs) are a kind of potential catalyst support for alkene hydroformylation. However, the synthesis of phosphine-POPs with strong π-acceptor is still a challenge. Herein, we report the synthesis of phosphine-POPs with different π-acceptor properties [POL-P(Pyr)3, CPOL-BPa&PPh3-15, and CPOL-BP&PPh3-15] and evaluated their performances as ligands to coordinate with Rh(acac)(CO)2 for hydroformylation of alkenes. We found that the Rh center with stronger π-acceptor phosphine-POPs showed better catalytic performance. Rh/CPOL-BPa&PPh3-15 with strong π-acceptor bidentate phosphoramidites showed obviously higher activity and regioselectivity (TON = 7.5 × 103, l/b = 26.1) than Rh/CPOL-BP&PPh3-15 (TON = 5.3 × 103, l/b = 5.0) with weaker π-acceptor bidentate phosphonites. Particularly, the TON of the hydroformylation reached 27.7 × 103 upon using Rh/POL-P(Pyr)3 which possessed tris(1-pyrrolyl)phosphane coordination sites. Overall, our study provides an orientation to design phosphine-POPs for hydroformylation reactions.

Alcohol Synthesis by Cobalt-Catalyzed Visible-Light-Driven Reductive Hydroformylation

A cobalt-catalyzed reductive hydroformylation of terminal and 1,1-disubstituted alkenes is described. One-carbon homologated alcohols were synthesized directly from CO and H2, affording anti-Markovnikov products (34-87% yield) with exclusive regiocontrol (linear/branch >99:1) for minimally functionalized alkenes. Irradiation of the air-stable cobalt hydride, (dcype)Co(CO)2H (dcype = dicyclohexylphosphinoethane) with blue light generated the active catalyst that mediates alkene hydroformylation and subsequent aldehyde hydrogenation. Mechanistic origins of absolute regiocontrol were investigated by in situ monitoring of the tandem catalytic reaction using multinuclear NMR spectroscopy with syngas mixtures.