Characteristics of phosphinated styrene-divinylbenzene copolymer containing RuCl2(PPh3)3 for 1-hexene isomerization

Summary Chloromethylated styrene-divinylbenzene(S-DVB) copolymer beads were prepared in macroporous type via direct copolymerization of chloromethylstyrene and divinylbenzene and then phosphinated. Dichlorotris(triphenylphosphine)ruthenium, RuCl₂(PPh₃)₃, was anchored on the phosphinated S-DVB copolymer, and then applied to the isomerization of 1-hexene. The physical properties of the catalysts varied with degree of crosslinking and type of pore-forming agents. Anchoring the ruthenium complex onto the phosphinated S-DVB resin favored trans-isomer and stabilized the catalyst in the isomerization of 1-hexene comparing with the homogeneous reaction. Solvent effects on catalytic activities of polymer-anchored catalysts were also discussed.     

Synthesis,molecular, crystal and electronic structure of [RuCl2(PPh3)2(C3N2H4)2]

The reaction of [RuCl₂(PPh₃)₃] complex with pyrazole has been examined. A new ruthenium complex – [RuCl₂(PPh₃)₂(C₃N₂H₄)₂] has been obtained and characterised by IR and UV–Vis measurements. Crystal and molecular structure of the complex has been determined.     

Formylation with supercritical carbon dioxide over Ru/Al2O3 modified by phosphines: heterogeneous or homogeneous catalysis?

The formylation of 3-methoxypropylamine with hydrogen and “supercritical” carbon dioxide over Ru-based catalysts was studied. In this solventless process, carbon dioxide acts as both reactant and solvent. Interestingly, Ru/Al₂O₃ modified by the phosphine 1,2-bis(diphenylphosphino)ethane (dppe) showed a high formylation activity at 100% selectivity, comparable to those of the homogeneous catalysts RuCl₂(dppe)₂ and RuCl₂(PPh₃)₃. Analysis of the reaction mixture by ICP-OES and structural studies by in situ X-ray absorption spectroscopy discovered that the presence of the phosphine modifier led to the formation of a homogeneous ruthenium catalyst.     

Hydroxyl group effect in novel NNN type pyridine based ruthenium (II) complex for the transfer hydrogenation of ketones

The new NNN type pyridine ligands were prepared by using low cost and readily available starting materials and metalated with RuCl₂(PPh₃)₃ to obtain ruthenium(II) complexes. All structures were illuminated by NMR, HRMS, and FT-IR spectroscopy. The complexes exhibited good catalytic activity in transfer hydrogen reaction of ketones and it was found that a hydroxyl group on β-position of the pyridine ring had a dramatic effect on the catalyst efficiency.     

Homogeneous catalytic hydrogenation of poly(styrene-co-butadiene) using a ruthenium based Wilkinson catalyst

Summary Poly(Styrene-co-butadiene) can be quantitatively hydrogenated using tris(triphenyl phosphine) ruthenium(II) chloride, RuCl₂(PPh₃)₃ as catalyst. The effect of temperature, pressure and catalyst concentration on both the rate and degree of hydrogenation have been studied. The hydrogenated elastomers have been characterized by IR, ¹H NMR and TGA.Ref. 1     

Catalytic hydrogenation of nitrile rubber using palladium and ruthenium complexes

The catalytic hydrogenation of acrylonitrile‐butadiene copolymer (nitrile rubber, NBR) using Pd(OAc)₂ or RuCl₂(PPh₃)₃ catalysts has been investigated in order to produce a totally saturated nitrile rubber. The hydrogenation of NBR is effective with both catalysts and achieved total conversion under the appropriate reaction conditions. In the case of palladium the effects of reaction parameters such as reaction temperature, pressure, time, catalyst concentration, and NBR concentration have been investigated. Even though both ruthenium‐ and palladium‐based catalysts are effective in the production of HNBR, the former requires harsh reaction conditions and has the drawback of gel formation under high conversion, motivating the migration to RuCl₂ (PPh₃)₃ as an alternative catalyst. The degree of hydrogenation was determined by IR and NMR spectroscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Ring‐opening polymerization of lactones using RuCl2(PPh3)3 as initiator: Effect of hydroxylic transfer agents

ε‐Caprolactone and δ‐valerolactone were polymerized in bulk at 150°C using the ruthenium(II) complex RuCl₂(PPh₃)₃ as initiator in the presence of 1,3‐propanediol (PD) with a series of alcohols as coinitiators. Polymerization of lactones proceeds via ruthenium(II) alkoxide active centers. ¹H‐NMR analysis revealed that the ruthenium complex reacted with the alcohol, generating in situ a ruthenium alkoxide. This species became a more active initiator of ring‐opening polymerization than was RuCl₂(PPh₃)₃. The obtained polylactones were characterized by ¹H‐ and ¹³C‐NMR and matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF). The results showed the formation had occurred of α,ω‐telechelic PCL and PVL diols, in which PD had been incorporated into the polymer backbone. Depending on the nature of the alcohol used as coinitiator, PCLs with different end groups could be synthesized. Insertion of an alcohol as an end group (benzyl alcohol, n‐octanol, or isopropanol) or into the polymeric backbone (propanediol) provided support for the conclusion that a classical coordination–insertion mechanism was operating during lactone polymerization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

A convenient one-step synthesis of alkenyl-phosphonio complexes of ruthenium(II), rhodium(III) and iridium(III)

Alkenyl-phosphonio complexes of ruthenium(II), rhodium(III) and iridium(III) were prepared by reactions of [(p-cymene)RuCl₂(PPh₃)] or [C_p^*MCl₂(PPh₃)] (M=Rh, Ir; C_p^*=C₅Me₅) with 1-ethynylbenzene and triphenylphosphine in the presence of KPF₆.     

Acyclic diene metathesis (ADMET) oligomerization of divinyltetramethyldisiloxane in the presence of rhodium and ruthenium complexes

Acyclic diene metathesis (ADMET) polymerization of divinyltetramethyldisiloxane in the presence of rhodium [RhCl(COD)]₂ and ruthenium RuCl₂(PPh₃)₃ catalysts led predominantly to linear oligomers [M _n=1815,M _w/M _n=1.16] if the rhodium catalyst was used or to mixtures of dimeric and trimeric oligomers if the ruthenium complex was applied. The rhodium complex appeared to be the first effective catalyst for ADMET polymerization of divinyldisubstituted organosilicon compounds.Part 14 in the series Metathesis of Silicon-Containing Olefins: for Part 13, see Ref. 8.     

Catalytic hydrogenation of nitrile–butadiene copolymer emulsion

Two processes have been developed for the selective hydrogenation of the CC bonds in nitrile–butadiene rubber emulsions (NBR emulsions) in the presence of a number of RuCl₂(PPh₃)₃ complex catalysts. One of the processes is carried out in a homogeneous system, in which an organic solvent, which can dissolve the NBR polymer and catalyst and which is compatible with the emulsion, is used. The other process is carried out in a heterogeneous system, in which an organic solvent which is capable of dissolving the catalyst and swelling the polymer particle but is not miscible with the aqueous emulsion phase, is used. In both processes, quantitative hydrogenation of the CC bonds of the NBR emulsion is achieved in the presence of RuCl₂(PPh₃)₃. It is also found that the addition of certain types of additives can improve the activities of the Ru-based catalysts. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 667-675, 1997     

Homogeneous catalytic hydrogenation of canola oil using a ruthenium catalyst

Dichlorodicarbonylbis (triphenylphosphine) ruthenium (II), RuCl₂ (CO)₂ (PPh₃)₂, was investigated as a catalyst for edible oil hydrogenation in a preliminary screening of potential catalysts for producing partially hydrogenated fats with lowtrans-isomer content. Refined, bleached and deodorized canola oil was hydrogenated using 1.77 × 10⁻⁵ − 6.64 × 10⁻⁴ mol/kg-oil of ruthenium catalyst equivalent to 1.79 × 10⁻⁴ − 6.71 × 10⁻³ wt% Ru. The effects of temperature (50–180 C) and pressure (50–750 psig) on reaction rate,trans-isomer content and fatty acid composition were examined. The activities of RuCl₂ (CO)₂ (PPh₃)₂ and nickel (Nysel HK-4 and AOCS standard nickel catalyst) were compared on a molar basis. At 4.40 × 10⁻⁴ mol/kg-oil (0.0026 wt/Ni or 0.0044 wt% Ru), 140 C and 50 psig, the nickel catalysts were completely inactive, but the ruthenium catalyst produced an IV drop of 40 units in 60 min. At 110 C, 750 psig and 1.34 × 10⁻⁴ mol/kg-oil (1.35 × 10⁻³ wt% Ru), a hydrogenation rate of 0.89 ΔIV/min and a maximumtrans-isomer content of 10.4% (IV=45.0) was obtained with the ruthenium catalyst.     

Asymmetric transfer hydrogenation of ketones by N,N-containing quinazoline-based ruthenium(II) complexes

The novel set of quinazoline-based chiral ligands was synthesized starting from optically pure amino acids. Coordination with RuCl₂(PPh₃)dppb gave ruthenium(II) N-heterocyclic complexes 4b–d. The structure of complex 4b was fully illuminated by X-ray crystallography. The steric environment of these chiral ruthenium complexes 4b–d was evaluated in asymmetric transfer hydrogenation (ATH) of prochiral ketones in the presence of NaOⁱPr by using 2-propanol as the hydrogen source and solvent. The resultant catalytic system can achieve very good enantioselectivities (up to 91%) and high yields (up to 99%).     

Transfer hydrogenation and transfer hydrogenolysis. X. Selective hydrogenation of methyl linoleate by indoline and isopropyl alcohol

The selective hydrogenation of methyl linoleate was studied using indoline and isopropyl alcohol as hydrogen sources. Many transition metal compounds and metallic palladium were examined as catalysts. High selectivity to monoenes and little formation oftrans isomers were realized under mild conditions in some reaction systems. For example, the system in which isopropyl alcohol and RuCl₂(PPh₃)₃ were used as hydrogen donor and catalyst was excellent. Also in the hydrogen transfer from indoline to the linoleate catalyzed by PdCl₂ and (NH₄)₂PdCl₄, high selec-tivity was realized. In the RuCl₂(PPh₃)₃-isopropyl alcohol, (NH₄)₂PdCl₄-indoline and PdCl₂-indoline system, methylcis- trans conjugated octadecadienoate was reduced rapidly with complete selectivity, where-as the same hydrogen transfer systems resulted in little if any reaction with methyl oleate. High selec-tivity in the reduction of linoleate is presumed to be realized through prior conjugation of the substrate.     

Influence of ruthenium alkylidene complexes bearing tricyclohexylphosphine or 3-bromopyridine ligand on the properties of fluorine containing polymers

The catalytic performance of ruthenium alkylidene complexes bearing tricyclohexylphosphine or 3-bromopyridine ligand in the ring opening metathesis polymerization (ROMP) of fluorine containing monomers, exo-N-4-fluorophenyl-7-oxanorbornene-5,6-dicarboximide (FPhONDI) and exo-N-4-fluorophenyl-norbornene-5,6-dicarboximide (FPhNDI) was investigated. Pure monomers were subjected to ROMP with RuCl₂(PCy₃)₂(CHPh) (I), RuCl₂(PCy₃)(H₂IMes)(CHPh) (II), RuCl₂(3-Br-py)₂(PCy₃)(CHPh) (III) and RuCl₂(3-Br-py)₂(H₂IMes)(CHPh) (IV). The polymers were fully characterized using NMR, DSC, SEM and GPC. Catalysts I–IV displayed significant ROMP activity, allowing for the synthesis of the corresponding polymers with polydispersity indices (PDIs) in the range of 1.4–4.0. High molecular weight polymers (Mw up to 4.95 x10⁵) were prepared in yields up to 90 %, depending on the initiator and monomer used.     

Ruthenium‐Catalyzed Remote Electronic Activation of Aromatic C?F Bonds

The tandem isomerization and nucleophilic aromatic substitution of allylic fluoro‐substituted benzylic alcohols is described for the first time. In the presence of the ruthenium complex Ru(PPh₃)₃(CO)(H)₂, 1‐(4‐fluorophenyl)prop‐2‐en‐1‐ol is converted into the corresponding para‐amino ketone or para‐phenolic substituted ketone.     

Cyclohexene hydrogenation using Group VIII metal complexes as catalysts in heterogeneous and homogeneous conditions

The stability and catalytic behaviour of a ruthenium complex with chloride and tridecylamine as ligands were studied. The hydrogenation of cyclohexene carried out in mild conditions, both in homogeneous and heterogeneous conditions, was used as a test reaction. FTIR and XPS results show that the active species is the complex itself, which is stable under the reaction conditions. XPS determination shows that the ruthenium complex is tetra‐coordinated, suggesting that its formula is [RuCl₂(NH₂(CH₂)₁₂CH₃)₂]. This ruthenium complex supported on γ‐Al₂O₃ is more active and sulfur‐resistant than the same complex unsupported and even more than a nickel complex with the above mentioned ligands. The Ru complex, supported or not, is also more active and sulfur‐resistant than a conventional Ru/γ‐Al₂O₃ catalyst evaluated in the same operational conditions. © 2001 Society of Chemical Industry     

Polymerization of 1,3-butadiene with MgCl2-supported cobalt catalysts activated by ordinary alkylaluminums

MgCl₂-supported CoBr₂ catalysts were prepared from mixture of MgCl₂ and CoBr₂L₂ (L = triphenylphosphine or pyridine) in toluene. Polymerization of 1,3-butadiene was conducted over the catalysts combined with ordinary alkylaluminums as cocatalyst. The CoBr₂(PPh₃)₂/MgCl₂ catalyst gave polybutadiene with approximately 80% of 1,2 units, whereas cis-1,4-poly-butadiene was obtained with the CoBr₂(C₅H₅N)₂/MgCl₂ catalyst. Addition of triphenylphospine to the latter catalyst caused a marked increase in the content of 1,2 units. The content of 1,2 units could be thus controlled in the range from 0 to 80% by changing the amount of triphenylphosphine. On the other hand, the CoBr₂(PPh₃)₂/MgCl₂ catalyst with very low content of CoBr₂(PPh₃)₂ hardly displayed any activity. Addition of dimethoxydiphenylsilane to the catalyst gave polybutadiene containing 90 % of 1,2 units with a fairly high activity.     

Selective catalytic hydrogenations in a microfluidics-based high throughput flow reactor on ion-exchange supported transition metal complexes: A modular approach to the heterogenization of soluble complex catalysts

Water-soluble ruthenium(II) and rhodium(I) complexes containing monosulfonated triphenylphosphine (mtppms) ligands were immobilized on commercially available anion-exchangers. The resulting solid catalysts were suitable for use in a microfluidics-based flow reactor (H-Cube™) of high throughput capability. With the heterogenized [{RuCl₂(mtppms)₂}₂] disubstituted alkynes were hydrogenated to cis-alkenes with up to 85% selectivity, while the use of the immobilized [RhCl(mtppms)₃] yielded 1,2-diphenylethane as the major product. The ruthenium catalyst also reduced trans-cinnamaldehyde to 3-phenylpropanal selectively and catalyzed the isomerization of 1-octen-3-ol to octan-3-one. This simple and versatile method of the immobilization of water-soluble complexes yields active and durable molecularly dispersed yet solid catalysts.     

Easily Accessible Ring Opening Metathesis and Atom Transfer Radical Polymerization Catalysts based on Arene,Norbornadiene and Cyclooctadiene Ruthenium Complexes Bearing Schiff Base Ligands

A group of four mixed ligand ruthenium(II)‐Schiff base complexes has been synthesized and characterized. These complexes are easily accessible from [RuCl₂(p‐cymene)]₂, [RuCl₂(NBD)]_n, [RuCl₂(COD)]_x and salicylaldimine salts. They have been found to serve as good catalyst precursors for ring‐opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP) of different vinyl monomers. The catalytic activity and the control over the produced polymer can be dramatically improved after the addition of additives such as Et₂AlCl and (n‐Bu)₂NH.     

Homogeneous Catalytic Hydrogenation of Bio‐Oil and Related Model Aldehydes with RuCl2(PPh3)3

A homogeneous RuCl₂(PPh₃)₃ catalyst was prepared for the hydrogenation of bio‐oil to improve its stability and fuel quality. Experiments were first performed on three model aldehydes of acetaldehyde, furfural and vanillin selected to represent the linear aldehydes, oxygen heterocyclic aldehydes and aromatic aldehydes in bio‐oil. The results demonstrated the high hydrogenation capability of this homogeneous catalyst under mild conditions (55–90 °C, 1.3–3.3 MPa). The highest conversion of the three model aldehydes was over 90 %. Furfural and acetaldehyde were singly converted to furfuryl alcohol and ethanol after hydrogenation, while vanillin was mainly converted to vanillin alcohol, together with a small amount of 2‐methoxy‐4‐methylphenol and 2‐methoxyphenol. Further experiments were conducted on a bio‐oil fraction extracted by ethyl acetate and on the whole bio‐oil at 70 °C and 3.3 MPa. Most of the aldehydes were transformed to the corresponding alcohols, and some ketones and compounds with C–C double bond were converted to more stable compounds.