Improvement of Productivity for Aqueous Biphasic Hydroformylation of Methyl 10‐Undecenoate: A Detailed Phase Investigation

The overall productivity of the aqueous biphasic hydroformylation of the castor oil‐derived methyl 10‐undecenoate is increased. To increase the reaction rate, the miscibility of water and the fatty compound is increased by addition of the green solvent 1‐butanol as co‐solvent. For the first time, the concentration of solvents, substrate, and product within the reaction process is experimentally examined in a biphasic system under 20 bar pressure of synthesis gas and 140 °C. A reactor to get samples of both phases is developed to determine the quarternary mixture of the reaction system presented in a four‐dimensional tetrahedron diagram. With the knowledge gained about the reaction and its drivers, it is possible to increase the efficiency of the reaction process reported so far. With simultaneously high reaction rates (turn over frequency = >5000 h^?1), the space–time yield of the reaction reaches values of >120 g L^?1h^?1 and can be improved significantly without negatively affecting catalyst leaching. Practical Applications: Most polymers are made of petrochemicals. Here, the development of a highly efficient process for the formation of bifunctional molecules starting from technical grade methyl 10‐undecenoate made from castor oil in an aqueous biphasic reaction system is presented. By rhodium catalyzed hydroformylation, an aldehyde ester is formed which can be used to create alcohols, carboxylic acids, and amines. Subsequently, these molecules can be used as polymer precursors in polycondensation reactions.     

The influence of organic solvents on transphosphatidylation by phospholipase D from peanut in anhydrous organic solvents

Phospholipase D (PLD) is widely used for the transphosphatidylation of phospholipids, which is conventionally performed in biphasic systems. The influence of organic solvents on transphosphatidylation by peanut PLD in anhydrous organic solvents was studied and, for the first time, compared to that of a biphasic system in this paper. The results demonstrated that PLD activity from peanut was influenced by solvents of different polarity in anhydrous organic solvents, and the influence tendency of organic solvents (diethyl ether, chloroform, methylenechloride) on transphosphatidylation by peanut PLD in anhydrous organic solvents was the same as that in a biphasic system consisting of water and a hydrophobic organic solvent.     

PdCl2(bipy) complex—An efficient catalyst for Heck reaction in glycol–organic biphasic medium

The Palladium complex PdCl₂(bipy) (1) was found to be efficient in catalyzing the Heck reaction of aryl halides in a biphasic system comprising ethylene glycol along with an organic solvent. A proper tailoring of the organic phase ensured that the leaching of the catalyst to the organic phase was negligible. The catalyst was active for the Heck reaction of a number of olefins, aryl halides, in presence of organic and inorganic bases. The PdCl₂(bipy) catalyst was stable and could be recycled for five times without any loss in activity and selectivity. A major advantage of this work is that unlike hitherto reported biphasic systems; it does not employ a water-soluble ligand to achieve biphasic catalysis.     

Comparison of supports for the direct synthesis of hydrogen peroxide from H2 and O2 using Au–Pd catalysts

The direct synthesis of hydrogen peroxide from H₂ and O₂ using a range of supported Au–Pd alloy catalysts is compared for different supports using conditions previously identified as being optimal for hydrogen peroxide synthesis, i.e. low temperature (2 °C) using a water–methanol solvent mixture and short reaction time. Five supports are compared and contrasted, namely Al₂O₃, -Fe₂O₃, TiO₂, SiO₂ and carbon. For all catalysts the addition of Pd to the Au only catalyst increases the rate of hydrogen peroxide synthesis as well as the concentration of hydrogen peroxide formed. Of the materials evaluated, the carbon-supported Au–Pd alloy catalysts give the highest reactivity. The results show that the support can have an important influence on the synthesis of hydrogen peroxide from the direct reaction. The effect of the methanol–water solvent is studied in detail for the 2.5 wt% Au–2.5 wt% Pd/TiO₂ catalyst and the ratio of methanol to water is found to have a major effect on the rate of hydrogen peroxide synthesis. The optimum mixture for this solvent system is 80 vol.% methanol with 20 vol.% water. However, the use of water alone is still effective albeit at a decreased rate. The effect of catalyst mass was therefore also investigated for the water and water–methanol solvents and the observed effect on the hydrogen peroxide productivity using water as a solvent is not considered to be due to mass transfer limitations. These results are of importance with respect to the industrial application of these Au–Pd catalysts.     

Mixtures of Ionic Liquids and Water as a Medium for Efficient Enantioselective Hydrogenation and Catalyst Recycling

In a screening of ligands, ionic liquids and reaction conditions in the Rh‐catalyzed hydrogenation of enamides, a novel multi‐phase reaction system consisting of an ionic liquid (IL) and water (wet ILs) was found to give the most promising results. In many cases such IL/water combinations were superior compared to conventional organic solvents and biphasic ILs/organic co‐solvents media with respect to catalytic performance as well as to catalyst separation and recycling. So far, the best results were obtained with Rh‐ferrocenyl‐diphosphine catalysts (>99% ee). Generally, somewhat lower ees were observed at higher pressure. However, this effect was less pronounced with wet ILs than with conventional solvents. It is shown that IL/water combination allow repeated catalyst recycling without significant loss of activity and that industrially relevant turnover numbers of >10,000 can be obtained.     

Selective dimerisation of 1-butene in biphasic mode using buffered chloroaluminate ionic liquid solvents — design and application of a continuous loop reactor

The dimerisation of 1-butene using (cod)Ni(hfacac) as catalyst has been investigated in different chloroaluminate ionic liquids. Systems prepared by buffering an acidic ionic liquid with weak organic bases proved to be very suitable solvents for the reaction. The reaction takes place in biphasic reaction mode with facile catalyst separation and catalyst recycling. The high intrinsic dimer linearity of catalyst is maintained, but with significant enhancement of catalyst activity and of the selectivity to the dimer product over that observed in toluene solvent. For further investigation, a continuous reactor was designed. Our results in continuous mode show the general technical applicability of the selective Ni-catalysed dimerisation in chloroaluminate ionic liquids using a loop reactor concept.     

Development of a continuous process for the hydroformylation of long-chain olefins in aqueous multiphase systems

The challenging task of homogeneous catalysis is the efficient combination of reaction and catalyst recycling. In the hydroformylation of long-chain olefins generally cobalt-based catalysts are used, but in our investigation we used rhodium-based catalysts, because of their higher activity in comparison to cobalt catalysts. In hydroformylation reactions, the recycling of the expensive rhodium catalyst as well as the selectivity to linear aldehydes are very challenging. Multiphase systems offer the possibility to increase the interfacial area during reaction on the one hand and to separate the metal–ligand complexes easily from the organic product phase after reaction, to recycle the expensive catalyst for further reactions, on the other hand. Solubilisers such as surfactants or polar solvents can be used to formulate such a tuneable solvent system. Upon cooling of the reaction mixture, phase separation is achieved. Based on that combination of reaction and phase separation for catalyst recycling, a novel process concept was developed for the hydroformylation of long-chain olefins. In order to show the applicability of that concept in a continuous process a fully automated miniplant was designed.     

Hydroformylation of 1-octene using rhodium–phosphite catalyst in a thermomorphic solvent system

The use of a liquid–liquid biphasic thermomorphic or temperature-dependent multicomponent solvent (TMS) system, in which the catalyst accumulates in one of the liquid phases and the product goes preferably to the other liquid phase, can be an enabling strategy of commercial hydroformylation processes with high selectivity, efficiency and ease of product separation and catalyst recovery. This paper describes the synthesis of n-nonanal, a commercially important fine chemical, by the hydroformylation reaction of 1-octene using a homogeneous catalyst consisting of HRh(PPh₃)₃(CO) and P(OPh)₃ in a TMS-system consisting of propylene carbonate (PC), dodecane and 1,4-dioxane. At a reaction temperature of 363 K, syngas pressure of 1.5 MPa and 0.68 mM concentration of the catalyst, HRh(CO)(PPh₃)₃, the conversion of 1-octene and the yield of total aldehyde were 97% and 95%, respectively. With a reaction time of 2 h and a selectivity of 89.3%, this catalytic system can be considered as highly reactive and selective compared to conventional ones. The resulting total turnover number was 600, while the turnover frequency was 400 h^?1. The effects of increasing the concentration of 1-octene, catalyst loading, partial pressure of CO and H₂ and temperature on the rate of reaction have been studied at 353, 363 and 373 K. The rate was found to be first order with respect to concentrations of the catalyst and 1-octene, and the partial pressure of H₂. The dependence of the reaction rate on the partial pressure of CO showed typical substrate inhibited kinetics. The kinetic behavior differs significantly from the kinetics of conventional systems employing HRh(CO)(PPh₃)₃ in organic solvents. Most notable are the lack of olefin inhibition and the absence of a critical catalyst concentration. A mechanistic rate equation has been proposed and the kinetic parameters evaluated with an average error of 5.5%. The activation energy was found to be 69.8 kJ/mol.     

The tetramethylguanidine catalyzed Baylis–Hillman reaction: Effects of co-catalysts and alcohol solvents on reaction rate

We report here the effects on the rate of the tetramethylguanidine catalyzed Baylis–Hillman reaction of addition of co-catalysts or alcohol solvents. We find that the use of phenol as a co-catalyst leads to significant rate acceleration. The reaction is best performed at 48 °C, with the reaction reaching completion within 1 h. The catalyst mixture works for aromatic aldehydes but not aliphatic aldehydes. Using methanol and ethanol as solvents has also been investigated and a rate acceleration over the solvent free case is observed but not to the same extent as with phenol.     

Microemulsion Systems with Rhodium Tris(3-sulfophenyl)phosphine Trisodium Salt Complex for Product Isolation and Catalyst Recycling in the Hydrogenation of Dimethyl Itaconate

Microemulsion systems with the nonionic surfactant p-tert-octylphenoxy polyethoxyethanol (OP9.5EO), the anionic surfactant dioctyl sulfosuccinate sodium salt (DOSS) and the narrow range nonionic surfactant alkyl polyethylene glycol ether (C10EO5) were used as solvent systems in the catalytic hydrogenation of dimethyl itaconate (DMI) catalysed by the water soluble catalyst complex Rh-TPPTS in order to achieve product isolation and catalyst recycling. The DOSS systems, which are more sensitive to the substrate and catalyst addition allowed for the hydrogenation to proceed with an initial hydrogenation rate about three times higher than with the nonionic surfactants, when the surfactant concentration was 15 wt%. Systems with 3 wt% surfactant were used in order to accomplish catalyst recycling. With a biphasic DOSS mixture a turnover number (TON) of 1,200 mol of DMI hydrogenated per mol of catalyst (Rh) was obtained in 3 consecutive runs. A three-phase system for the OP9.5EO mixture allowed the catalyst to be recycled 3 times and a TON of 1,500 in 4 runs was obtained. A TON of 800 in 2 runs was obtained using a three-phase C10EO5 mixture.     

Selection of Biphasic Liquid Systems in Liquid‐Liquid Chromatography Using Predictive Thermodynamic Models

The possibility of using thermodynamic models for screening biphasic liquid systems, including systems for which liquid‐liquid equilibrium data are not available, is demonstrated. The liquid‐liquid equilibrium in different biphasic systems and the partition coefficients of solutes in these systems are predicted with UNIFAC and COSMO‐RS. The predictions are based only on the molecular structure of the solutes and solvents. The advantages and limitations of the two models are explored using fourteen solutes and five biphasic solvent systems. The overall results show that the theoretically selected systems closely match the systems chosen by experimental screening. The experimental work needed for selecting a suitable biphasic system for a given separation problem can be drastically reduced with the help of predictive thermodynamic models.     

Solventless synthesis of cyclic carbonates from carbon dioxide and epoxides catalyzed by silica-supported ionic liquids under supercritical conditions

A silica-supported ionic liquid proved to be an efficient heterogeneous catalyst for solventless synthesis of cyclic carbonates from epoxides and carbon dioxide under supercritical conditions, which requires no additional organic solvents either for the reaction or for the separation of product. The effects of reaction time, temperature and other reaction parameters on the reaction are investigated. High yields with excellent selectivity were obtained. The purity of product separated directly by filtration from the reaction mixture, reached 99% without further purification process. Moreover, the catalyst can be easily recovered by filtration and reused over four times with slight loss of its catalytic activity. The process represents a simple, ecologically safer, cost-effective route to cyclic carbonates with high product quality, as well as easy product recovery and catalyst recycling.     

11α hydroxylation of 16α, 17‐epoxyprogesterone in biphasic ionic liquid/water system by Aspergillus ochraceus

BACKGROUND: The improved efficiency of steroid biotransformation using the biphasic system is generally attributed to the positive effect on the solubility of substrate in aqueous media. A promising alternative for the application of organic solvents in biphasic systems is the use of ionic liquids (ILs). This study aims to investigate the applicability of the biphasic ILs/water system for 11α hydroxylation of 16α, 17‐epoxyprogesterone (HEP) by Aspergillus ochraceus. RESULTS: Of the seven ILs tested, [C₃mim][PF₆] exhibited the best biocompatibility, with markedly improved biotransformation efficiency. In the [C₃mim][PF₆]‐based biphasic system, substrate conversion reached 90% under the condition in which buffer pH, volume ratio of buffer to ILs, cell concentration, and substrate concentration were 4.8, 10/1, 165 g L^?1 and 20 g L^?1, respectively. This is more efficient than that of the monophasic aqueous system. The effects of the cations and anions of these ILs on the 11α hydroxylation of 16α, 17‐epoxyprogesterone (HEP) by A. ochraceus is also discussed. CONCLUSION: The above results showed that IL/water biphasic system improved the efficiency of 11α hydroxylation of 16α, 17‐epoxyprogesterone (HEP) by A. ochraceus, thus suggesting the potential industrial application of ILs‐based biphasic systems for steroid biotransformation. © 2012 Society of Chemical Industry     

Solid acids as substitutes for sulfuric acid in the liquid phase nitration of toluene to nitrotoluene and dinitrotoluene

Our results demonstrate that sulfuric acid supported on preshaped silica is a good catalyst for the nitration of toluene to dinitrotoluene using 65 wt.% nitric acid with respect to catalyst performance (activity, selectivity, regenerability) and catalyst handling (storage, stirring, separation). It is imperative to carefully control the water content of the catalyst prior to reaction in order to obtain high activity. The reusability of the catalyst without compromising performance has been demonstrated. Non-polar solvents seem to be required in order to prevent dissolution of the impregnated acid. Hence, the application of acetic anhydride as a solvent with potential water trapping ability was unsuccessful. Solvent-free operation is limited by the necessity to maintain a mixture that can be stirred. Hence, a maximum conversion of about 30% is achievable for the nitration of nitrotoluene to dinitrotoluene in one reaction cycle.     

Highly efficient and recyclable ruthenium nanoparticle catalyst for semihydrogenation of alkynes

Ru nanoparticles were used as catalysts for semihydrogenation of alkynes for the first time. Poly(ethylene glycol) (PEG)-stabilized Ru nanoparticles were used as catalysts for semihydrogenation of various terminal alkynes in thermoregulated PEG biphasic system, which allows for not only an efficient homogeneous catalytic reaction, but also an easy biphasic separation and reuse of catalyst. Under the optimized conditions, various terminal alkynes were hydrogenated to the corresponding alkenes with high selectivity. After reaction, the Ru nanoparticle catalyst could be separated from products by simple phase separation and recycled for ten times without evident loss in activity and selectivity.     

Biocatalytic ester synthesis in ionic liquid media

Ionic liquids have shown potential as green reaction media compared with organic solvents, mainly due to their lack of vapour pressure. In non‐aqueous enzymology, ionic liquids are opening up new fields. The advantages of using ionic liquids over the use of organic solvents as reaction medium for biocatalysis include enhancement of enzyme activity, stability and selectivity. In this work, the enzymatic synthesis of esters in ionic liquids has been extensively reviewed. Numerous examples of the application of ionic liquids as reaction medium for the enzymatic production of esters have been included. The effect of the nature of the ionic liquid on activity, selectivity and stability of enzymes which catalyze esters synthesis has been carefully analysed. Innovative reaction methodologies for the biosynthesis of esters, including ionic liquid/supercritical carbon dioxide biphasic systems and the integrated reaction/separation processes using supported liquid membranes based on ionic liquids have been revised. Copyright © 2010 Society of Chemical Industry     

Production and Scale-up of phosphatidyl-tyrosol catalyzed by a food grade phospholipase D

Highly purified phosphatidyl-tyrosol was obtained by using a food grade phospholipase D from Actinamadure sp. transphosphatidylation in a GRAS (Generally Recognized As Safe) biphasic medium. The reaction medium, comprised of an aqueous phase and ethyl butyrate, has been considered as an alternative to other biphasic systems previously reported utilizing more harmful organic solvents. The purpose of the present study was to purify phosphatidyl-tyrosol from a transphosphatidylation reaction mixture by using a procedure readily scalable to obtain a new valuable food ingredient. Initially, phosphatidyl-tyrosol was purified via semi-preparative HPLC equipment to be used as analytical standard. The best results of the transphosphatidylation reaction were obtained for two different PC concentrations, namely 83 and 166 mmol/L, with PC conversion of ca. 97 and 94% (w/w) and a final phosphatidyl-tyrosol concentration of 81 and 157 mmol/L, respectively. Finally, the procedure was scaled-up and 40 g of highly purified phosphatidyl-tyrosol (97% (w/w)) were readily purified by centrifugation without involving the utilization of organic solvents.     

Influence of solvent composition and degree of reaction on the formation of surface microtopography in a thermoset siloxane-urethane system

The effects of solvent composition and degree of reaction prior to film formation leading to the formation of a biphasic microtopographical surface in a crosslinked siloxane-urethane coating system were explored. For the solvent composition study, a D-optimal mixture design study was carried out using methyl n-amyl ketone (MAK), toluene, ethyl 3-ethoxypropionate (EEP), butyl acetate (BA) and isopropyl alcohol (IPA) as solvents. The study revealed that the presence of slow evaporating solvents MAK, EEP and the absence of fast evaporating solvent IPA in the solvent composition with a minimal amount of BA favored formation of a structured surface. Control over the domain size could be obtained by varying the MAK:EEP ratio in solvent compositions having a fixed amount of BA. The effect of mixing time on the formation of surface domains was studied. At short mixing times (<2 h) and long mixing times (>7 h), no surface phase separation is observed, while at intermediate times a ‘window’ was found where surface microdomains of similar size are generated. Doubling the level of catalyst halves the mixing time required to generate surfaces with microdomains. Scanning electron microscopy (SEM) studies with energy dispersive X-ray mapping and dynamic mechanical analysis (DMA) were done in order to understand the development of the phases in the PDMS-polyurethane system.     

Hydroformylierung mit wasser- und methanollöslichen Rhodiumcarbonyl/Phenyl-sulfonatoalkylphosphan-Katalysatorsystemen – Ein neues Konzept für die Hydroformylierung höhermolekularer Olefine

Hydroformylation with Water- and Methanol-soluble Rhodium Carbonyl/phenyl-sulfonatoalkyl-phosphine Catalyst Systems – A New Concept for the Hydroformylation of Higher Molecular Olefins The heterogenization of the homogeneous hydroformylating catalyst system enables the recovery of the catalyst from the reaction products by a simple phase separation but it is unfavourable that many advantages of the homogeneous catalysis are given up by this procedure. To avoid this drawback we used rhodium carbonyl/tert. phosphine catalyst systems soluble as good in methanol as in water for the homogeneously catalyzed hydroformylation of the olefin in methanolic solution. Only after reaction the product mixture is heterogenized by adding water forming an aqueous phase containing the catalyst system. It was shown by the hydroformylation of n-tetradecene-1 with rhodium carbonyl/phenyl-sulfonatoalkyl-phosphine catalyst systems that this new conception is very useful for the oxo reaction of high-molecular olefins.     

离子液体桥连的聚苯乙烯负载型2,2,6,6-四甲基哌啶氧化物催化剂的稳定性

研究将小分子催化剂2,2,6,6-四甲基哌啶氧化物通过化学共价键键合离子液体桥连的方法负载在聚苯乙烯氯球上，制备负载型催化剂。考察其在N₂气氛的热稳定性、溶剂中的溶胀性以及两相反应体系(NaClO/NaBr、CH2Cl₂/H₂O)中的化学稳定性。结果表明，负载型催化剂在反应温度低于180 ℃表现出较好的热稳定性，且在苯甲醇催化氧化过程中可以循环使用20次，苯甲醇转化率大于95%。所得催化剂具有亲水亲油的两亲性，适用于两相体系的催化环境，比直接负载2,2,6,6-四甲基哌啶氧化物的催化剂有更好的耐溶剂性及稳定性。