Hydroformylation Of Vinyl Acetate Research Articles

Selective Association Enforced by the Confinement Effect To Boost the Regioselectivity of Vinyl Acetate Hydroformylation

Selective Association Enforced by the Confinement Effect To Boost the Regioselectivity of Vinyl Acetate Hydroformylation

Preparation and Characterization of Rh/MgSNTs Catalyst for Hydroformylation of Vinyl Acetate: The Rh0 was Obtained by Calcination

A simple and practical Rh-catalyzed hydroformylation of vinyl acetate has been synthesized via impregnation-calcination method using silicate nanotubes (MgSNTs) as the supporter. The Rh0 (zero valent state of rhodium) was obtained by calcination. The influence of calcination temperature on catalytic performance of the catalysts was investigated in detail. The catalysts were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS), atomic emission spectrometer (ICP), and Brunauer–Emmett–Teller (BET) surface-area analyzers. The Rh/MgSNTs(a2) catalyst shows excellent catalytic activity, selectivity and superior cyclicity. The catalyst could be easily recovered by phase separation and was used up to four times.

Alkali and Alkaline Earth Cation-Decorated TiO2 Nanotube-Supported Rh Catalysts for Vinyl Acetate Hydroformylation

Alkali and alkaline earth cation-decorated TiO2 nanotube (TNT)-supported rhodium catalysts were synthesized and characterized by inductively-coupled plasma optical emission spectrometer, surface characterization analyzer, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transforming infrared spectrum, respectively. Their catalytic performances were evaluated by the hydroformylation of vinyl acetate. Results showed that both the conversion rate of vinyl acetate and selectivity for aldehyde were improved after Rh/TNTs were modified by alkali or alkali-earth cations. Such improved selectivity for aldehyde might be attributed to the presence of alkali or alkaline earth cations which enhanced CO adsorption, while the high conversion rate of vinyl acetate was likely due to the proper interaction of Lewis acid–base between cations modified TNTs and vinyl acetate.

Titanate Nanotube-Supported Au–Rh Bimetallic Catalysts: Characterization and Their Catalytic Performances in Hydroformylation of Vinyl Acetate

A series of titanate nanotube-supported metal catalysts (M/TNTs, M = Rh, Au orAu–Rh) were facilely synthesized. The effects of different Au contents, reduction processes and sequence of loading metals on their catalytic performances in the hydroformylation of vinyl acetate were comparatively investigated. The results showed that some Au and Rh formed bimetallic particles. Furthermore, the presence of Au in catalysts could significantly improve the selectivity of reaction for aldehydes. Compared with the monometallic catalysts (Rh0.33/TNTs-1 and Au0.49/TNTs-2), the resultant bimetallic catalysts exhibited significantly higher selectivity for aldehydes as well as higher TOF values in the hydroformylation of vinyl acetate. Among them, Au0.52/Rh0.32/TNTs-12 displayed the best catalytic performance. The corresponding selectivity for aldehydes was as high as 88.67%and the turnover frequency (TOF) reached up to 3500 h−1. In addition, for the reduction of Rh3+ and Au3+ ions, the photo-reduction and ethanol-reduction were the optimal techniques under the present conditions, respectively.

Rh/DNA Nanoparticles, Synthesis, Characterization and Catalytic Activity in “On Water” Asymmetric Hydroformylation Reaction

AbstractDNA‐stabilized Rh NPs were synthesized by the chemical reduction of Rh(acac)(CO)2 (acac=acetylacetonate) in water at 80 °C. The obtained nanoparticles, Rh/DNA, were characterized by various spectroscopic and microscopic methods, such as IR, UV‐Vis, XRD (X‐ray diffraction), ICP‐AES (Inductively coupled plasma atomic emission spectroscopy), EDX (Energy‐dispersive X‐ray spectroscopy analysis), TEM (Transmission electron microscopy), and SEM (Scanning electron microscopy) analyses. Their catalytic activity was successfully investigated in the “on water” hydroformylation of styrene. The conversion of styrene and chemoselectivity towards aldehydes were 100%. A high iso/n ratio was also obtained, up to 6.1 and 16.7 with PPh3 (triphenylphosphine) and (R)‐BINAP (2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl) ligands respectively. In the hydroformylation of vinyl acetate with Rh/DNA, performed in the presence of a chiral BINAP ligand “on water”, high enantioselectivity was obtained, up to 49% ee. These results were significantly better than when utilizing Rh(acac)(CO)2 as a catalyst under the same conditions.

Hydroformylation of vinyl acetate and cyclohexene over TiO2 nanotube supported Rh and Ru nanoparticle catalysts.

TiO2 nanotube (TNT) supported Rh and Ru nanoparticle catalysts were prepared via impregnation-photoreducing procedure and characterized with various methods. Their catalytic performances in hydroformylation were evaluated by using vinyl acetate and cyclohexene as substrates. The results indicate that the presence of Ru in the catalysts can enhance the catalytic activity of catalysts for the hydroformylation of vinyl acetate, but do not play the same role in the hydroformylation of cyclohexene; the sequence of loading metal has a significant effect on the catalytic performances of the title catalysts. Additionally, it is found that Ru/TNTs shows catalytic activity for the hydroformylation of vinyl acetate though it does not for the hydroformylation of cyclohexene.

Supramolecularly Regulated Ligands for Asymmetric Hydroformylations and Hydrogenations.

Herein we report the use of polyether binders as regulation agents (RAs) to enhance the enantioselectivity of rhodium-catalyzed transformations. For reactions of diverse substrates mediated by rhodium complexes of the α,ω-bisphosphite-polyether ligands 1-5,a-d, the enantiomeric excess (ee) of hydroformylations was increased by up to 82 % (substrate: vinyl benzoate, 96 % ee), and the ee value of hydrogenations was increased by up to 5 % (substrate: N-(1-(naphthalene-1-yl)vinyl)acetamide, 78 % ee). The ligand design enabled the regulation of enantioselectivity by generation of an array of catalysts that simultaneously preserve the advantages of a privileged structure in asymmetric catalysis and offer geometrically close catalytic sites. The highest enantioselectivities in the hydroformylation of vinyl acetate with ligand 4 b were achieved by using the Rb[B(3,5-(CF3)2 C6 H3)4] (RbBArF) as the RA. The enantioselective hydrogenation of the substrates 10 required the rhodium catalysts derived from bisphosphites 3 a or 4 a, either alone or in combination with different RAs (sodium, cesium, or (R,R)-bis(1-phenylethyl)ammonium salts). This design approach was supported by results from computational studies.

Synthesis and characterization of TiO2 nanotube supported Rh-nanoparticle catalysts for regioselective hydroformylation of vinyl acetate

Three procedures: the impregnation-borohydride reduction procedure, the impregnation-alcohol reduction procedure and the impregnation-photoreducing procedure, were utilized for preparing TiO2 nanotube supported rhodium nanoparticle catalysts.

Regioselective hydroformylation of vinyl esters catalyzed by Rh(acac)(CO)2 with simple and efficient diphosphinite ligands

Simple and efficient diphosphinite ligands were evaluated in rhodium catalyzed hydroformylation of vinyl acetate. The effect of various reaction variables like temperature, pressure, substrate/Rh ratio, P/Rh ratio, solvents, time and different types of phosphorous ligands were studied. The diphosphinite ligand exhibited a considerable impact on the hydroformylation of vinyl esters and provided good turnover number (up to 10,000) with excellent regioselectivity (99%) to branched aldehyde. Wide range of vinyl esters including long chain aliphatic vinyl esters (up to C18) were well tolerated to provide good to excellent yield of desired product.

Novel Bis(1,3,2-diazaphospholidine) Ligands for Asymmetric Catalysis

A family of modularly designed chiral bis(1,3,2-diazaphospholidines) with N-aryl substituents (NP-PN) is reported. These compounds have been prepared in two steps from readily available (R,R)-1,2-diaminocyclohexane and tetrachlorodiphosphines. Examples in the set differ in the backbone and the aryl substituents, aiming at their application in asymmetric catalysis. Thus, [Rh(NBD)(NP-PN)]BF4 complexes lead to active catalysts in the hydrogenation of methyl α-acetamidoacrylate, which provide enantioselectivities up to 96% ee. In addition, NP-PN ligands also generate active catalysts in the hydroformylation of vinyl acetate, leading to high regioselectivities (iso:n ratio higher than 99:1) and enantioselectivities up to 65% ee.

Regioselective Rhodium-Diphosphine Ligand Catalyzed Hydroformylation of Vinyl Acetate

Rhodium-catalyzed hydroformylation of vinyl acetate with the use of diphosphine ligands was studied. A high regioselectivity (branched:linear of 99:1) and activity (TOF: 4000 h −1 ) under optimum conditions were achieved by using a 2,2'-bis(diphenylphosphino methyl)-1,1'-biphenyl ligand. The high turnover number (9200) obtained under mild conditions and stability of the catalyst indicates that it would be useful for industrial vinyl acetate hydroformylation. 研究了双膦配体对铑催化的乙酸乙烯酯氢甲酰化反应的促进作用, 结果表明, 在优化反应条件下, 以双膦化合物 2,2’-二 (二苯膦甲基)-1,1’-联苯 (BISBI) 为配体时, 铑催化乙酸乙烯酯氢甲酰化反应的 TOF (转化频率) 值达到 4000 h −1 , 生成 2-乙酰氧基丙醛的选择性 > 99%. 当在较温和的条件下 Rh/BISBI 催化乙酸乙烯酯氢甲酰化反应较长时间时 TON (转化数) 值达到 9200, 成醛率超过 90%, 2-乙酰氧基丙醛选择性仍保持 > 99%. High regioselectivity and activity were achieved in Rh-catalyzed hydroformylation of vinyl acetate with the use of diphosphine ligands. The turnover number was 9200 and the catalyst was stable after 12 h.

Regioselective hydroformylation of vinyl acetate catalyzed by rhodium complex of naphthyl-based monodentate bulky phosphine and phosphite ligands

The hydroformylation of vinyl acetate was carried out using rhodium complex of naphthyl-based monodentate bulky phosphine and phosphite ligands. All the naphthyl-based ligands favored the formation of desire branched aldehyde. High turnover frequency with excellent regioselectivity to branched aldehyde and high selectivity to aldehyde were observed with bulky phosphite ligands. The effect of partial pressure of CO and H2, concentration of vinyl acetate, stirring rate and solvents on the hydroformylation of vinyl acetate catalyzed by Rh/bulky phosphite were examined precisely in order to improve the catalytic activity and selectivity. In contrast to conventional organic solvents, the significant influence on the activity and selectivity was observed in organic carbonates (‘green’ solvent) particularly in propylene carbonate (PC). The PC/catalyst system could be recycled without significant loss of activity and selectivity.

Highly Efficient Rhodium Catalysts for the Asymmetric Hydroformylation of Vinyl and Allyl Ethers using C1‐Symmetrical Diphosphite Ligands

AbstractHere, we describe the successful application of novel glucofuranose‐derived 1,3‐diphosphites in the rhodium‐catalysed asymmetric hydroformylation of vinyl acetate, 2,5‐dihydrofuran and 2,3‐dihydrofuran. In the hydroformylation of vinyl acetate, total regioselectivity and high ee (up to 73%) were obtained. When 2,3‐ and 2,5‐dihydrofuran were the substrates, total chemo‐ and regioselectivities were achieved together with ees up to 88%. These results correspond to the highest ee values reported to date in the asymmetric hydroformylation of these substrates. The HP‐NMR studies of the [RhH(CO)2(L)] species (L=15 and 17) demonstrated that both ligands coordinate to the Rh centre in an eq‐eq fashion. The complex [RhH(CO)2(15)] was detected as a single isomer with characteristic features of eq‐eq coordination. However, the broadening of the corresponding signals indicated that this species is rapidly interchanging in solution. In contrast, complex [RhH(CO)2(17)] was detected as a mixture of two conformational isomers at low temperature due to the greater flexibility of the monocyclic backbone of this ligand.

Regioselective and rapid hydroformylation of vinyl acetate catalyzed by rhodium complex modified bulky phosphite ligand

Abstract The regioselective hydroformylation of vinyl acetate catalyzed by rhodium complex of monodentate phosphite ligand, tri-1-naphthylphosphite P(ONp) 3 , was investigated. The P(ONp) 3 ligand exhibited a considerable impact on the rate and selectivity of hydroformylation of vinyl acetate, notably high turnover frequency (up to 11,520 h −1 ) with excellent regioselectivity (99%) to the preferred branched aldehyde and high selectivity to aldehyde (93%). Significant results with the substrate having less reactive character toward hydroformylation and practically easy accessibility of the ligand (synthesized from inexpensive compound, 1-naphthol) make this system very attractive.

ChemInform Abstract: Diazaphospholidine Terminated Polyhedral Oligomeric Silsesquioxanes in the Hydroformylation of Vinyl Acetate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Novel diazaphospholidine terminated polyhedral oligomeric silsesquioxanes in styrene and vinyl acetate hydroformylation: Synthesis and molecular dynamics studies

New diazaphospholidine POSS macromolecules have been synthesised and tested in styrene and vinyl acetate hydroformylation. Whilst some of them have shown activity, others precipitated upon mixing with the rhodium precursor preventing its efficient use. Molecular dynamics has been used to help understand these observations. Rigid and compact dendritic structures with phosphine groups engineered to have low mobility but high probability of sitting at distances favouring bidentate coordination with the rhodium precursors are necessary for the macromolecular ligands to be active. More flexible structures having lower probability of phosphine separations suitable for bidentate complex formation are more prone to form oligomeric dendritic species and hence to crosslink the macromolecules and precipitate.

Diazaphospholidine terminated polyhedral oligomeric silsesquioxanes in the hydroformylation of vinyl acetate

The poorly active, monodentate SemiEsphos phosphine has been turned into an active ligand for rhodium catalysed vinyl acetate hydroformylation by attachment to the periphery of a polyhedral oligomeric silsesquioxane.

Ferrocene-based bidentate phosphonite ligands for rhodium(I)-catalyzed enantioselective hydroformylation

A new class of chiral modular bidentate phosphonite ligands has been synthesized in good overall yields by using cheap trans-1,2-diaminocyclohexane and ferrocene as starting materials, and applied in the Rh(I)-catalyzed asymmetric hydroformylation of vinyl acetate and styrene to afford the corresponding optically active aldehydes with good regioselectivity (up to 16.9 b/ l ratio) and moderate to good enantioselectivity (up to 83% ee). The substituents on the backbone of the ligands are found to exhibit a remarkable effect on both the regio- and enantioselectivity of the catalysis.

Asymmetric hydroformylation of olefins catalyzed by rhodium nanoparticles chirally stabilized with ( R)-BINAP ligand

Rhodium nanoparticles have been conveniently synthesized by one-pot chemical reduction of aqueous rhodium chloride (RhCl 3·3H 2O) dispersed in toluene solution in the presence of amphiphilic tetraoctylammonium bromide (TOAB) and chiral ( R)-BINAP at ambient conditions. The resulting highly dispersed rhodium nanoparticles show small and narrowly distributed core sizes (1.5–2.0 nm). The chirally stabilized rhodium nanoparticles were also immobilized on silica by impregnation to give the corresponding supported catalysts. 31P MAS NMR results and IR spectra of adsorbed CO confirm that chiral ( R)-BINAP ligands stabilize the nanoparticles by coordinative interaction between phosphine and rhodium, and produce chirally catalytic active sites on the rhodium nanocatalysts. Chirally stabilized catalysts exhibit high regioselectivity and chiral induction ability for the asymmetric hydroformylation of olefins. The supported rhodium nanocatalysts show the increased activities compared to the unsupported catalysts (e.g. from 12 to 22 h −1 for the hydroformylation of styrene). One hundred percentage regioselectivity of branched aldehyde and up to 59% ee were obtained for the hydroformylation of vinyl acetate.

High Rate and Highly Selective Vinyl Acetate Hydroformylation in Ionic Liquids as Solvent or Cosolvent

The hydroformylation of vinyl acetate to form 2-acetoxypropanal (an important intermediate in the synthesis of the environmentally friendly solvent ethyl lactate) catalyzed by Rh(CO)2(acac) using phosphite or phosphine ligands was investigated in ionic liquids as reaction media (neat and as blends) or as additives to organic solvents. The ionic liquid had a significant effect on the selectivity of the hydroformylation of vinyl acetate, with very high TOFs being realized and selectivities of over 99% being obtained for the desired branched product at >95% selectivity for aldehyde products in reactions up to 0.3 mol scale. This effect could be obtained for relatively low volumes of the ionic liquid in an organic solvent, and combinations of benefits were observed by blending ionic liquids. It was also shown that the ionic liquid/catalyst could be recycled without loss of activity.