Aqueous Biphasic Medium Research Articles

Aqueous Biphasic Hydroaminomethylation Enabled by Methylated Cyclodextrins: Sensitivity Analysis for Transfer into a Continuous Process

Hydroaminomethylation (HAM) is a highly efficient homogeneously catalyzed autotandem reaction converting alkenes into valuable amine products with water being the only coproduct. This work reports for the first time the scale-up of the highly regioselective HAM of 1-decene with diethylamine for a potential continuous process application in a green and sustainable aqueous biphasic medium. The catalytic system Rh/SulfoXantphos and randomly methylated β-cyclodextrin (RAME-β-CD) were herein dissolved in the plain aqueous phase. The addition of cyclodextrins as a green mass transfer agent remarkably increases the reaction rate as well as the selectivity toward linear amines, but they can also support solid content precipitation in this reaction system due to up-scaling effects. Therefore, parameters such as catalyst concentration, organic volume fraction, cyclodextrin concentration, and recyclability were investigated regarding the stability and activity of the system. Especially the organic volume fraction had a decisive influence on solid content precipitation. High regio- and chemoselectivities of 35 and 82%, respectively, at nearly full conversion were achieved toward the linear product amine. The catalytic system was further recycled in batch and scaled up into a 2100 mL autoclave without loss in activity and selectivity. Finally, a continuous process concept was proposed for an extensive investigation regarding long-term stability of the catalytic system.

Kinetics of 1‐decene hydroformylation in an aqueous biphasic medium using a water‐soluble Rh‐sulfoxantphos catalyst in the presence of a cosolvent

AbstractThe kinetics of hydroformylation of 1‐decene has been studied in an aqueous biphasic medium using a water‐soluble Rh‐sulfoxantphos catalyst in the presence of N‐methyl pyrrolidone as a cosolvent at 383‐403 K. The rate was found to be first order, with concentrations of catalyst and olefin and partial order, with concentrations of hydrogen in the liquid phase. The plot of rate versus excess ligand and CO concentrations passed through maxima, indicating negative order dependence at higher concentrations. These trends have been interpreted based on the established hydroformylation mechanism. High selectivity towards the linear aldehyde was maintained (n: iso ratio > 30). An empirical rate equation has been proposed which was found to be in good agreement with the observed rate data within the experimental error. The activation energy was evaluated to be 74.76 kJ/mol.

Hydroformylation of Higher Olefins in Aqueous Biphasic Medium Using Rhodium-Sulfoxantphos Catalyst: Activity and Selectivity Study

Hydroformylation of higher olefins such as 1-hexene, 1-octene, 1-decene and 1-dodecene has been studied in an aqueous biphasic medium using water-soluble Rh-sulfoxantphos complex catalyst. The effect of temperature, presence of various co-solvents and concentration of co-solvent on the reaction rate and chemo and regioselectivity was investigated. N-Methyl pyrrolidone (NMP) was found to be the best co-solvent, which enhances the rate dramatically (4-96 fold) as compared to the reactions in aqueous-organic biphasic medium for hydroformylation of higher olefins. Catalyst recycle study was performed to check the leaching of metal in organic phase.

Aqueous biphasic hydroformylation of olefins: From classical phosphine-containing systems to emerging strategies based on water-soluble nonphosphine ligands

ABSTRACTThis review provides an overview of recent developments in the area of aqueous biphasic hydroformylation of higher olefins using metal catalysts and surfactants, cosolvents, thermoregulated ligands, cyclodextrins, and most importantly emerging water-soluble nonphosphine ligands. Water-soluble phosphine ligands have been widely explored for aqueous biphasic hydroformylation; however, phosphines are generally expensive and are prone to oxidation hence the recent interest in exploring other ligands. Various approaches have been used to introduce hydrophilicity to the ligands. The catalytic activity of monometallic and heterobimetallic systems containing nonphosphine ligands in aqueous biphasic media is emphasized in this review.

Kinetic and Mechanisms of the Aqueous-Biphasic Hydroformylation of Olefins Contained in Naphtha Cuts Catalyzed by RhH(CO)(TPPTS)3 [TPPTS: Tri(sodium m-sulfonated-phenyl)phosphine

A kinetic study of the individual olefins present in naphtha, their mixture (synthetic naphtha) and the olefins present in a real naphtha was carried out using RhH(CO)(TPPTS)3 [TPPTS: tri(sodium m-sulfonated-phenyl)phosphine] as the catalyst precursor in aqueous-biphasic medium (toluene/water or naphtha/water), under mild reaction conditions: 80 °C, 800 psi (55.4 atm) and 600 rpm. The study consisted in the characterization of real naphtha, the selection of the model olefins, the preparation of synthetic naphtha, followed by hydroformylation of the individual olefins, of the olefin mixture and of a real naphtha cut. For 1-hexene aqueous-biphasic reaction, a kinetic study based on initial rate method showed a first order dependence on catalyst, substrate and dissolved hydrogen concentrations, whereas a fractional order was observed for carbon monoxide concentration. This kinetic results are in accord with the traditional hydroformylation mechanism, the hydrogenolysis of rhodium-acyl species being the rate-determining step of the cycle. From all the reaction profiles, it was corroborated by using the integral method that the dependence with respect to the olefin concentration was of first order for the aqueous-biphasic hydroformylation of individual olefins and their mixture, as well as for the olefins present in real naphtha cut. These results are important because of knowing the kinetics and mechanisms of the hydroformylation of the olefins present in naphtha, it is possible to improve the activity of the precatalyst and/or to design new ones for this type of application, i.e. the improving of the fuel quality through the green technology of aqueous-biphasic catalysis. A kinetic study of the individual olefins present in naphthas, their mixture (synthetic naphtha) and the olefins present in a real naphtha was carried out in aqueous-biphasic medium using RhH(CO)(TPPTS)3 [TPPTS = tri(sodium m-sulfonated-phenyl)phosphine] as the catalyst precursor in a aqueous-biphasic media, under mild reaction conditions: 80 °C, 800 psi (55.4 atm) and 600 rpm. The kinetic results are in accord with the traditional hydroformylation mechanism.

Lipase‐catalyzed synthesis of sorbitol octanoate in aqueous biphasic medium and its use in a green formulation process of oil‐in‐water food nanoemulsions

AbstractBACKGROUNDSugar‐based surfactants are highly relevant alternative ingredients for food grade formulations. Nevertheless, the design of sustainable manufacturing processes is still ongoing.RESULTSSorbitol ester surfactants were synthesized by lipase‐catalyzed esterification in solvent‐free conditions. Octanoic acid was dispersed in a 70 wt% sorbitol aqueous solution (containing the enzyme). The maximal conversion of 23.5 mole % of esterified fatty acid per mole of loaded fatty acid was obtained after 48 h in optimal conditions. The performance of the reactor was affected by both the nature and amount of the reactants and the dispersion state. Detailed structural analysis demonstrated that lipase from Candida rugosa specifically catalyzed the acylation of sorbitol on primary hydroxyl groups. Sorbitol esters accumulated exclusively in the oil phase, which led to easy and efficient product recovery. Oil phase containing the sorbitol esters could be used directly for preparing oil‐in‐water nanoemulsion without adding any other stabilizer. These nanoemulsions exhibited good stability after 7 days storage at 25°C or 60°C.CONCLUSIONA green manufacturing process for food grade oil‐in‐water nanoemulsions was designed involving a lipase‐catalyzed esterification step which produced in situ the required surfactant. Nanoemulsions were prepared without using any other stabilizer. © 2017 Society of Chemical Industry

Tetraphenolate c-methylcalix[4]resorcinarene as a new heterogeneous phase transfer catalyst for ring-opening of triaryl substituted pyrylium salts in aqueous biphasic medium

This study reports, for the first time, the application of water-insoluble tetraphenolate c-methylcalix[4]resorcinarene as an efficient and heterogeneous phase transfer catalyst at room temperature. This supramolecule could facilitate the nucleophilic reactions through the formation of a host–guest complex in the organic-aqueous interfacial layer. Moreover, the recovered catalyst can be used for several times without serious decrease in activity.

Manganese Salen Compounds Embedded within Cross-Linked Chiral Polyethylenimine: Asymmetric Epoxidation in an Aqueous Biphasic Medium

Manganese Salen Compounds Embedded within Cross-Linked Chiral Polyethylenimine: Asymmetric Epoxidation in an Aqueous Biphasic Medium

Aqueous biphasic hydroformylation in the presence of cyclodextrins mixtures: evidence of a positive synergistic effect

Mixtures of randomly methylated cyclodextrins of various sizes have been evaluated in the rhodium-catalysed hydroformylation of higher olefins in an aqueous biphasic medium. A marked positive non-linear effect on 1-tetradecene conversion is observed when the CD molar ratio in the mixture is modified. The formation of 2:1 ternary inclusion complexes between RAME-CDs and the olefin is supposed to be responsible for the extra conversion observed.

ChemInform Abstract: Green Oxidation in Water

AbstractReview: 175 refs.

A water soluble heteropolyoxotungstate as a selective, efficient and environment friendly oxidation catalyst

A series of water soluble Keggin type heteropolyoxotungstates have been tested as oxidation catalysts in aqueous-biphasic media with dilute H2O2 (30%) as the oxygen atom donor, without using any phase transfer agent. The Zn substituted polyoxoanion {(NH4)7Zn0.5[α-ZnO4W11O30ZnO5(OH2)]·nH2O} has been found to be the most efficient catalyst, which oxidizes a wide range of organic functionalities with good turnovers and high selectivities. The functionalities that undergo oxidations are: organic sulfides, pyridines, anilines, benzyl alcohols and benzyl halides. The oxidations of sulfides to sulfoxides and/or sulfones have been studied in detail, and a simple kinetic model consisting of two consecutive reactions, is shown to give good fit with the experimental data. In the catalytic system described here product isolation is easy, and the aqueous catalyst solution can be re-used several times with little loss in its efficiency.

Efficient aldol condensation in aqueous biphasic system under microfluidic conditions

A microfluidic system was applied to aldol reaction in aqueous biphasic medium. Advantageous aspects of microfluidic conditions, that is, efficient mixing, fast heat transfer, and residence time control led to the high-yielding reaction of acetone enolate with even α-proton-containing aldehydes in biphasic aqueous-acetone system, by minimizing the formation of self-condensation products.

CoCl 2(TPPTS) 2 catalyzed hydroformylation of 1-octene and 1-decene in the presence of surfactant and co-solvents in a biphasic medium

CoCl 2(TPPTS) 2 catalyzed hydroformylation of 1-octene and 1-decene was studied in an aqueous biphasic medium. The effect of temperature, pressure and addition of cetyltrimethylammonium bromide (CTAB) and tri( m-sulfophenyl)-phosphine (TPPTS) in the reaction mixture on the hydroformylation of alkenes was investigated. Increase in conversion of 1-octene and 1-decene with higher aldehyde selectivity was observed in the presence of CTAB. The leaching of cobalt complex, CoCl 2(TPPTS) 2, from aqueous phase to organic phase in presence of TPPTS was observed to decrease. There was slight decrease in the conversion on increasing the TPPTS to cobalt molar ratio. The addition of CTAB increases the conversion (95%) and selectivity (90–95%) for aldehyde whereas the addition of TPPTS facilitates the separation of organic–aqueous phase. Hydroformylation was also studied in the presence of ethanol and methanol under the optimum reaction conditions.

Catalytic hydrogenation of olefins and their mixtures using HRh(CO)(TPPMS) 3 complex in an aqueous biphasic medium

The synthesis and characterization of the catalyst precursor HRh(CO)(TPPMS) 3 was carried out by ligand exchange techniques starting from HRh(CO)(PPh 3) 3 with an excess of TPPMS ligand [TPPMS] = (C 6H 5) 2P( m-C 6H 4SO 3Na), or prepared in situ from RhCl 3·3H 2O and TPPMS under high purity syngas. When the hydrosoluble complex was used as a catalyst precursor in the two phase hydrogenation reaction of 1-hexene, cyclohexene, styrene and 2,3-dimethyl-1-butene, the main hydrogenated products were obtained with high conversion rates. Under the following reaction conditions T = 343 K, P = 13.6 atm, 600 rpm and S/C = 600/1, the substrates showed the following reactivity order: styrene > 1-hexene > cyclohexene > 2,3-dimethyl-1-butene. A quaternary equimolar mixture and one quaternary mixture which simulates the olefin quantities present in real naphtha, showed the same hydrogenation order. The catalyst showed recycling properties without significant loss of activity and sulfur tolerance when benzothiophene is present in the olefin mixtures.

Enantioselective Hydrogenation of Polar Substrates in Inverted Supercritical CO2/Aqueous Biphasic Media.

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, please click on HTML or PDF.

Aqueous biphasic catalysis with polyoxometalates: Oximation of ketones and aldehydes with aqueous ammonia and hydrogen peroxide

Na12[WZn3(H2O)2[ZnW9O34)2], easily self assembled from Na2WO4 and Zn(NO3)2, catalyses the in situ oxidation of ammonia with hydrogen peroxide to hydroxylamine, which further reacts with ketones and aromatic aldehydes in an aqueous biphasic medium without organic solvent to yield oximes as valuable intermediates.

Rhodium-catalyzed hydroformylation of C6 alkenes and alkene mixtures – a comparative study in homogeneous and aqueous-biphasic media using PPh 3, TPPTS and TPPMS ligands

The complexes RhH(CO)L 3, where L = PPh 3, P( m-C 6H 4SO 3Na) 3 (TPPTS), and (C 6H 5) 2P( m-C 6H 4SO 3Na) (TPPMS) were used as catalyst precursors for a comparative study of the catalytic hydroformylation of several C6 alkenes and alkene mixtures under moderate reaction conditions in homogeneous (PPh 3) and aqueous-biphasic (TPPTS, TPPMS) media. The biphasic systems are efficient for the hydroformylation of hex-1-ene, 2,3-dimethyl-1-butene, styrene, cyclohexene, and mixtures thereof, in water/ n-heptane at 80 °C. The main problem associated with these catalysts is their tendency to promote alkene isomerization if the effective syngas concentration in the liquid phases is low, but this side-reaction can be suppressed by using higher CO/H 2 pressures (54 atm). The selectivity of both water-soluble catalysts for linear products of hex-1-ene and for branched products of styrene is modest in comparison with the homogeneous system, which may limit their utility for classical oxo uses, but this is not a disadvantage for other interesting applications related to the hydroformylation of alkene mixtures and particularly to naphtha upgrading where linear and branched products are equally useful. The catalysts can be recycled without significant loss of activity and are resistant to the presence of benzothiophene in the mixture.

Hydroformylation of 1-hexene catalyzed by water soluble CoCl2(TPPTS)2 in biphasic medium

Abstract CoCl 2 (TPPTS) 2 catalyzed hydroformylation of 1-hexene was studied in an aqueous biphasic medium. The effect of temperature, pressure, and concentration of cobalt catalyst on the reaction was studied. At elevated temperatures and pressures, it gave >90% conversion with 68% selectivity for aldehyde and n / iso ratio of 3.0 for the aldehyde.

Alternative approach to the free radical bromination of oligopyridine benzylic-methyl group

We have undertaken a study on the influence of three solvents on the photobromination of two picolines. It shows that dichloromethane and benzene are better solvents than the classical carbon tetrachloride. The obtention of a good free radical bromination is described using aqueous biphasic media.