Organic Ligand‐Free Hydroformylation with Rh Particles as Catalyst†

Summary of main observation and conclusion An efficient and organic ligand-free heterogeneous catalytic system for hydroformylation of olefins is highly desirable for both academy and industry.In this study,simple Rh black was employed as a heterogeneous catalyst for hydroformylation of olefins in the absence of organic ligand.The Rh black catalyst showed good catalytic activity for a broad substrate scope including the aliphatic and aromatic olefins,affording the desired aldehydes in good yields.Taking the hydroformylation of ethylene as an example,86%yield of propanal and TOF of 200 h-1 were obtained,which was superior to the reported homogeneous catalytic systems.In addition,the catalyst could be reused five times without loss of activity under identical reaction conditions,and the Rh leaching was negligible after each cycle.     

Rhodium‐catalysed hydroformylation of 1‐octene using aryl and ferrocenyl Schiff base‐derived ligands

Monometallic and heterobimetallic complexes of Rh(I) bearing chelating N ,O ‐bidentate aryl‐ and ferrocenyl‐derived ligands have been synthesised via Schiff base condensation reactions, and characterised fully using ¹H NMR, ¹³C{¹H} NMR and Fourier transform infrared spectroscopies, elemental analysis and mass spectrometry. The new monometallic and heterobimetallic complexes were evaluated as potential catalyst precursors in the hydroformylation of 1‐octene at 95°C and 40 bar. The ferrocenylimine mononuclear compounds were inactive in the hydroformylation experiments. The Rh(I) monometallic and the ferrocene–Rh(I) heterobimetallic pre‐catalysts displayed good activity and conversion of 1‐octene as well as outstanding chemoselectivity towards aldehydes in the hydroformylation reaction.     

Evidence of colloidal rhodium formation during the biphasic hydroformylation of 1‐octene with thermoregulated phase‐transfer phosphine rhodium(I) catalyst

A thermoregulated phase‐transfer (TRPT) Rh(I) complex catalyst A prepared from Rh(acac)(CO)₂ and a thermoregulated ligand CH₃(OCH₂CH₂)_mPPh₂ (M_w = 918) was applied to the biphasic hydroformylation of 1‐octene, and a high activity with an aldehyde yield of 97.5% was demonstrated. After three recycling steps, the aldehyde yield gradually decreased. Transmission electron microscopy (TEM) revealed that after the first cycle Rh colloids were generated in situ in the aqueous phase, and in subsequent runs Ostwald ripening occurred. An independently prepared colloidal Rh(0) TRPT catalyst D also exhibited high hydroformylation activity under identical experimental conditions, and after two times of recycling an activity decrease was also observed. It is suggested that in situ from Rh(acac)(CO)₂ colloidal Rh particles are generated, which demonstrate thermomorphic behaviour and a high hydroformylation activity. Subsequently, agglomeration processes result in an activity decay, as observed in the TRPT Rh(I) complex catalyst system. Copyright © 2005 John Wiley & Sons, Ltd.     

Aqueous biphasic hydroformylation of higher alkenes and highly efficient catalyst recycling in the presence of a polar low boiling solvent

The hydroformylation of higher alkenes under aqueous biphasic reaction conditions with a rhodium catalyst derived from BISBIS (sodium salt of sulfonated 2,2′-bis (diphenylphosphinomethyl)-1,1′-biphenyl) in the presence of a polar low boiling point solvent was studied. The addition of ethanol greatly accelerated hydroformylation, such that the turnover frequency (defined as the moles of converted alkene per mole of Rh per hour) and the selectivity for linear aldehyde were up to 2095 h^?1 and 99 %, respectively. The catalytic system could be recycled for at least five runs without significant loss of activity in the aqueous biphasic hydroformylation of 1-octene; the rhodium content leaching in product mixtures detected by inductively coupled plasma atomic emission spectroscopy was < 0.1 ppm.     

Synthesis,characterization and hydroformylation activity of 7‐azaindolate‐bridged dinuclear rhodium(I)phosphines with pendant polar‐groups

New dinuclear Rh(I)–Phosphines of the types [Rh(µ‐azi)(CO)(L)]₂ ( 1,3 – 7 ) and [Rh(µ‐azi)(L)]₂ ( 8 ) with pendant polar groups, and a chealated mononuclear compound [Rh(azi‐H)(CO)(L)] ( 2 ) (where azi = 7‐azaindolate, L = polar phosphine) were isolated from the reaction of [Rh(µ‐Cl)(CO)₂]₂ with 7‐azaindolate followed by some polar mono‐ and bis‐phosphines ( L ₁ – L ₈ ). A relationship between Δδ³¹P‐NMR and ν(CO) values was considered to define the impact of polar‐groups on σ‐donor properties of the phosphines. These compounds were evaluated as catalyst precursors in the hydroformylation of 1‐hexene and 1‐dodecene both in mono‐ and biphasic aqueous organic systems. While the biphasic hydroformylations (water + toluene) gave exclusively the aldehydes, the monophasic one (aqueous ethanol) showed propensity to form both aldehydes and alcohols. The influence of bimetallic cooperative effects, and σ‐donor and hydrophilic properties of the phosphines with pendant polar‐groups in enhancing the yields and selectivity of hydroformylation products was emphasized. In addition, when strong σ‐donor phosphine was used, the π‐acceptor nature of pyridine ring of 7‐azaindolate spacer was found to be a considerable factor in facilitating the facile cleavage of CO group during hydroformylation and in supplementing the cooperative effects. Copyright © 2009 John Wiley & Sons, Ltd.     

Calix[4]arene‐based Bis‐phosphonites,Bis‐phosphites,and Bis‐O‐acyl‐phosphites as Ligands in the Rhodium(I)‐catalyzed Hydroformylation of 1‐Octene

New calix[4]arene‐based bis‐phosphonites, bis‐phosphites and bis‐O‐acylphosphites were synthesized and characterized. Treatment of these P‐ligands with selected rhodium and platinum precursors led to mononuclear complexes that were satisfactorily characterized. The solid state structure of the dirhodium(I) complex 14 has been determined by X‐ray diffraction. The two rhodium centres are bridged by two chloro ligands; one rhodium atom is further coordinated by calix[4]arene phosphorus atoms and the other by cyclooctadiene. The new calix[4]arene P‐ligands were tested in the Rh(I) catalyzed hydroformylation of 1‐octene. All Rh(I) complexes catalyzed the reaction leading to high chemoselectivity with regard to the formation of aldehydes. Yields and n/iso‐selectivities depended on the reaction conditions. Average yields of 80 % and n/iso‐ratios of about 1.3 to 1.5 were observed. High yields of aldehydes can be achieved using the methoxy substituted P‐ligands at low Rh:ligand ratios.     

The Effect of Metal‐Ligand Affinity on Fe3O4_Supported Co–Rh Catalysts for Dicyclopentadiene Hydroformylation

The catalytic performances of Co‐Rh/Fe₃O₄ catalysts modified with phosphine ligands (PPh₃) and its analogues on dicyclopentadiene hydroformylation were evaluated. Among these catalysts, Co‐Rh/Fe₃O₄ modified with tris(p‐trifluoromethylphenyl)phosphine was determined to be effective for monoformyltricyclodecanes production, whereas Co‐Rh/Fe₃O₄ modified with PPh₃ or tri‐p‐tolylphosphine was effective for the diformyltricyclodecanes production. To investigate the ligand effects, the complex catalyst system (Co‐Rh/Fe₃O₄ and phosphine ligand) was subjected to pretreatment with syngas and then characterized by thermogravimetry and differential thermal analysis (TG‐DTA). It was determined that the threshold decomposition temperature reflected the corresponding Rh‐phosphine interaction strength, affecting the catalytic selectivity toward different products. A weak Rh‐phosphine interaction was desirable to produce monoformyltricyclodecanes with fast reaction kinetics, whereas a strong Rh‐phosphine complex was required for the synthesis of diformyltricyclodecanes. In addition to the selectivity rule shown in the PPh₃ series, experiments with other ligands also demonstrated similar selectivity trends.     

Tetraphosphine/palladium‐catalyzed Suzuki–Miyaura coupling of heteroaryl halides with 3‐pyridine‐ and 3‐thiopheneboronic acid: an efficient catalyst for the formation of biheteroaryls

An easily prepared tetraphosphine N,N,N′,N′‐tetra(diphenylphosphinomethyl)‐1,2‐ethylenediamine (L1) associated with [Pd(η³‐C₃H₅)Cl]₂ affords an efficient catalyst for Suzuki–Miyaura coupling of 3‐pyridineboronic acid with heteroaryl bromides. Reaction could be performed with as little as 0.02 mol% catalyst and a high turnover number of 2500 is obtained. A wide range of substrates is investigated with satisfactory yields, and good compatibility with aminogroup‐substituted pyridines and unprotected indole is exhibited. This protocol can also be applied successfully to the reaction of heteroaryl bromides with 3‐thiopheneboronic acid. This Pd‐tetraphosphine catalyst efficiently restrains the poisoning effect from heteroaryls, and shows good stability and longevity. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydroformylation of 2,5‐norbornadiene in organic/aqueous two‐phase system and acceleration by cationic surfactants

The organic/aqueous biphasic hydroformylation of 2,5‐norbornadiene (NBD) was investigated for the first time using HRh(CO)(TPPTS)₃ (TPPTS: trisodium salt of tri(m‐sulphonylphenyl)phosphine) as the catalyst precursor. A comparison was made of homogeneous and biphasic systems. The optimum reaction parameters are discussed and the reaction mechanism is presented. In order to ensure the process attained high activity under moderate conditions, the effect of various cationic surfactants was tested in the biphasic hydroformylation of NBD. The results indicated that the hydroformylation of NBD in the biphasic system exhibited high activity and high selectivity to dialdehyde products under mild conditions. The addition of cationic surfactants markedly accelerated the reaction. A single long‐chain surfactant seemed to exert a greater impact on the hydroformylation of NBD than a double long‐chain surfactant. Moreover, the recycling of aqueous solution containing catalyst with or without surfactant was investigated. In the absence of the surfactant, the aqueous catalyst could be recycled six times without a significant decrease in activity and selectivity. Copyright © 2016 John Wiley & Sons, Ltd.     

有机-无机杂化L-Rh/SiO2氢甲酰化催化剂的研究Ⅰ.PPh3-Rh/SiO2的催化性能及表征

 利用有机-无机杂化的概念,以三苯基膦直接修饰Rh/SiO2制备了PPh3-Rh/SiO2多相催化剂. 在浆态床烯烃氢甲酰化反应中,该催化剂在10 MPa,373 K温和条件下的活性和选择性远高于Rh/SiO2的活性和选择性,与相应的均相催化剂HRhCO(PPh3)3的性能相当,且具有易分离的优点. 31P MAS NMR和XPS技术表征结果表明,催化剂中的配体PPh3与高度分散的Rh之间存在配位作用,形成了兼具多相和均相催化性能的有机-无机杂化催化剂. 该催化剂对不同碳数烯烃的氢甲酰化反应都具有较好的催化性能.     

Temperature‐responsive Catalyst for the Coupling Reaction of Carbon Dioxide and Propylene Oxide

The selective synthesis of polypropylene carbonate (PPC) and cyclic propylene carbonate (CPC) from coupling reaction of CO₂ and propylene oxide (PO) is a long term pursuing target. Here we report that a temperature controllable porphyrin aluminum catalyst using 5,10,15,20‐tetra(1,2,3,4,5,6, 7,8‐octahydro‐1,4:5,8‐dimethanoanthracen‐9‐yl)porphyrin as ligand, once in conjunction with suitable onium salt, achieved single cycloaddition or copolymerization reaction. Only cycloaddition reaction happened at temperature above 75 °C to produce 100% CPC, whereas copolymerization became dominant to afford PPC with selectivity over 99% at 25 °C, and the obtained PPC showed over 99% carbonate linkage and 92% head‐to‐tail structure. Based on systematic analysis of the electronic and steric feature in the porphyrin ligand, it was found that the electronic feature of the substituent in porphyrin ligand was decisive for PPC selectivity, porphyrin ligand bearing strong electron‐donating substituents displayed a significantly reduced tolerance towards increased temperature with respect to PPC formation. Therefore, temperature‐responsive catalyst could be designed by suitable modification in porphyrin ligand, and such accurate synthesis of target product by one catalyst may create a useful and facile platform for selective PPC or CPC production.     

[NiCl2(dppp)]‐Catalyzed Cross‐Coupling of Aryl Halides with Dialkyl Phosphite,Diphenylphosphine Oxide,and Diphenylphosphine

We present a general approach to C? P bond formation through the cross‐coupling of aryl halides with a dialkyl phosphite, diphenylphosphine oxide, and diphenylphosphane by using [NiCl₂(dppp)] as catalyst (dppp=1,3‐bis(diphenylphosphino)propane). This catalyst system displays a broad applicability that is capable of catalyzing the cross‐coupling of aryl bromides, particularly a range of unreactive aryl chlorides, with various types of phosphorus substrates, such as a dialkyl phosphite, diphenylphosphine oxide, and diphenylphosphane. Consequently, the synthesis of valuable phosphonates, phosphine oxides, and phosphanes can be achieved with one catalyst system. Moreover, the reaction proceeds not only at a much lower temperature (100–120 °C) relative to the classic Arbuzov reaction (ca. 160–220 °C), but also without the need of external reductants and supporting ligands. In addition, owing to the relatively mild reaction conditions, a range of labile groups, such as ether, ester, ketone, and cyano groups, are tolerated. Finally, a brief mechanistic study revealed that by using [NiCl₂(dppp)] as a catalyst, the Ni^II center could be readily reduced in situ to Ni⁰ by the phosphorus substrates due to the influence of the dppp ligand, thereby facilitating the oxidative addition of aryl halides to a Ni⁰ center. This step is the key to bringing the reaction into the catalytic cycle.     

Rhodium complexes with a new chiral nitrogen‐containing BINOL‐based diphosphite or phosphonite ligand: synthesis and application to hydroformylation of styrene and/or hydrogenation of prochiral olefins

Two new cationic rhodium(I) complexes with a chiral nitrogen‐containing BINOL‐based diphosphite or phosphonite ligand have been synthesized. Chiral diphosphite was prepared by the reaction of N‐phenyldiethanolamine with two equivalents of [(R)‐(1,1′‐binaphthalene‐2,2′‐diyl)]chlorophosphite. In its rhodium complex the ligand is bound to the metal via both phosphorus atoms, and a Rh–N interaction is also possible. Synthesis of the chiral phosphonite was achieved by the reaction of 2‐(N,N‐dimethylaminophenyl)‐bis(diethylamino)phosphine with one equivalent of R‐BINOL. In its rhodium complex, the ligand is P,N‐bonded, forming a five‐membered chelate ring. The first complex was applied to hydroformylation of styrene and displayed high activity and chemo‐ and regioselectivity, but unfortunately no asymmetric induction was found. Both complexes were evaluated in the hydrogenation of prochiral olefins with moderate activities and low enantioselectivities. Copyright © 2005 John Wiley & Sons, Ltd.     

Linear-selective hydroformylation of vinyl ether using Rh (acac)(2,2′-bis{(di[1H-indol-1-yl]phosphanyl)oxy}-1,1′-binaphthalene) – Possible way to synthesize 1,3-propanediol

Three bidentate phosphoramidite ligands were synthesized, characterized, and employed in Rh-catalyzed hydroformylation of vinyl ethers. The complex Rh(acac)(2,2′-bis{(di[1H-indol-1-yl]phosphanyl)oxy}-1,1′-binaphthalene} (acac = acetylacetone) (Rh- L4 ) was also synthesized and characterized. Rh- L4 showed good regioselectivity for the hydroformylation of vinyl ethers under mild reaction conditions: 2 MPa of syngas, 1:1 (H₂/CO) substrate/catalyst molar ratio 1000:1, and 60 °C. The linear selectivity was up to 98%, and in most cases was about 80%, with no hydrogenation product formation observed, which could be a potential way to synthesize 1,3-propanediol. A mechanism study including density functional theory computational analysis showed that both Rh–H and CO insertion steps in the hydroformylation of vinyl ether were linear-preferred in our catalyst system.     

Rhodium‐Catalyzed Hydroformylation of 1,1‐Disubstituted Allenes Employing the Self‐Assembling 6‐DPPon System

A rhodium‐catalyzed hydroformylation of 1,1‐disubstituted allenes is reported. Using a Rh^I/6‐DPPon catalyst system, one can obtain β,γ‐unsaturated aldehydes in high regio‐ and chemoselectivity. The Z‐configured product is formed with up to >95 % selectivity when unsymmetrically 1,1‐disubstituted allenes are submitted to the reaction conditions. This is the first time that these interesting building blocks are accessible by hydroformylation of allenes. The utility of this methodology is demonstrated by further transformations of one of the obtained products.     

高稳定性无膦配体乙烯氢甲酰化催化体系研究

高活性、高稳定性的无膦配体多相氢甲酰化催化体系研究是催化化学领域的重要课题。本文以乙烯氢甲酰化这一反应为目标,发展出含有不同含氧官能团的活性炭为载体的负载纳米铑催化材料。其中,当以Rh/C-3这一材料为催化剂时,乙烯氢甲酰化反应的转化频率可以达到57889 mol/mol/h。该催化剂可以在固定床反应器上稳定运行2500小时保持活性稳定。表征发现,碳材料表面的内酯基团 (-CO2-)对催化材料的活性和稳定性具有重要的作用。这一研究对高活性、高稳定性的非膦配体多相氢甲酰化催化体系研究具有一定的启示。     

Spiroketal‐Based Phosphorus Ligands for Highly Regioselective Hydroformylation of Terminal and Internal Olefins

A new class of bidentate phosphoramidite ligands, based on a spiroketal backbone, has been developed for the rhodium‐catalyzed hydroformylation reactions. A range of short‐ and long‐chain olefins, were found amenable to the protocol, affording high catalytic activity and excellent regioselectivity for the linear aldehydes. Under the optimized reaction conditions, a turnover number (TON) of up to 2.3×10⁴ and linear to branched ratio (l/b) of up to 174.4 were obtained in the Rh^I‐catalyzed hydroformylation of terminal olefins. Remarkably, the catalysts were also found to be efficient in the isomerization–hydroformylation of some internal olefins, to regioselectively afford the linear aldehydes with TON values of up to 2.0×10⁴ and l/b ratios in the range of 23.4–30.6. X‐ray crystallographic analysis revealed the cis coordination of the ligand in the precatalyst [Rh( 3 d )(acac)], whereas NMR and IR studies on the catalytically active hydride complex [HRh(CO)₂( 3 d )] suggested an eq–eq coordination of the ligand in the species.     

Combination of sp2‐ and sp3‐Type Phosphorus Atoms for Gold Chemistry: Preparation,Structure, and Catalytic Activity of Gold Complexes That Bear Ligated 2‐Silyl‐1,3‐diphosphapropenes

Kinetically protected 2‐silyl‐1,3‐diphosphapropenes that bear both sp²‐ and sp³‐type phosphorus atoms were employed in the preparation of gold complexes. The structural properties of the 1,3‐diphosphapropene digold(I) complexes were characterized by spectroscopic and crystallographic analyses, which revealed unique aurophilic interactions and conformational properties of the ligand. The 2‐silyl‐1,3‐diphosphapropene‐bis(chlorogold) complexes catalyzed cycloisomerization reactions of 1,6‐enyne derivatives even in the absence of silver co‐catalyst, and were able to be recovered after the reaction. The catalytic activity of the digold complexes primarily depended on the sp²‐type phosphorus atom and the silyl group, and could be tuned by the sp³‐phosphino group. Additionally, results on the catalytic activity of the digold complex in the presence and absence of silver salts showed considerable differences.     

Xantphite: A New Family of Ligands for Catalysis. Applications in the Hydroformylation of Alkenes

The novel bulky diphosphite (P∩P) ligands ( 3 and 4 ) based on the 2,7,9,9‐tetramethyl‐9H‐xanthene‐4,5‐diol ( 2 ) backbone were investigated in the Rh‐catalyzed hydroformylation of oct‐1‐ene, styrene, and (E)‐oct‐2‐ene. These diphosphites gave rise to very active and selective catalysts for the hydroformylation of oct‐1‐ene to nonanal with average rates>10000 (mol aldehyde)(mol Rh)⁻¹h⁻¹ (P(CO/H₂)=20 bar, T=80°, [Rh]=1 mM ) and maximum selectivities of 79% for the linear product. Relatively high selectivities towards the linear aldehyde (up to 70%, linear/branched up to 2.3) but very high activities (up to 39000 (mol aldehyde)(mol Rh)⁻¹h⁻¹) were observed for the hydroformylation of styrene in the presence of these bidentate ligands (P(CO/H₂)=2 – 10 bar, T=120°, [Rh]=0.2 mM ). Remarkable activities (up to 980 (mol aldehyde)(mol Rh)⁻¹h⁻¹) were achieved with these diphosphites for the hydroformylation of (E)‐oct‐2‐ene with selectivities for the linear product of 74% (l/b up to 2.8, P(CO/H₂)=2 bar, T=120°, [Rh]=1 mM ). A detailed study of the solution structure of the catalyst under catalytic conditions was performed by NMR and high‐pressure FT‐IR. The spectroscopic data revealed that under hydroformylation conditions, the bidentate ligands rapidly formed stable, well‐defined catalysts with the structure [RhH(CO)₂(P∩P)]. All the ligands showed a preference for an equatorial‐apical ( ea ) coordination mode in the trigonal bipyramidal Rh‐complexes, indicating that a bis‐equatorial ( ee ) coordination is not a prerequisite for highly selective catalysts.     

Studies on the Synthesis of Sulfur-Containing Polymer-Rhodium Complexes and Their Use as Catalysts for Hydroformylation

A kind of nonphosphine polymer catalyst has been synthesized by partial substitution of the chlorine atoms of poly(vinyl chloride) with -SR groups (n-propyl, n-hexyl, benzyl, and p-tolyl). Rhodium complexes of these sulfur-containing polymer ligands are highly active catalysts for the hydroformylation of α-olefins. At 60°C and 60 kg/cm², conversion of 1-hexene was nearly complete within 4–6 h. The rhodium to 1-hexene mole ratio was 1/800 to 1/1 000, and the catalyst could be reused once again without losing activity. The effects of reaction temperature, pressure, H₂/CO ratio, S/Rh ratio, concentration of catalyst, and reaction time on the catalyst's activity were examined. The possible mechanism of hydroformylation is discussed. A copolymer of butyl vinyl sulfide and acrylonitrile was synthesized and its rhodium complex was prepared. The catalytic acitvities of this complex for the hydroformylation of 1-hexene was also investigated.