Heteropolyanion-based Ionic Liquids Research Articles

Brønsted acidic Heteropolyanion-Based ionic Liquid:A highly efficient Reaction-induced Self-separation catalyst for Baeyer-Villiger reaction

A novel Brønsted acidic heteropolyanion-based ionic liquid (IL) ([MIMPS]3PW12O40) was synthesized and employed to catalyze the Baeyer-Villiger (BV) reaction to produce ε-Caprolactone (ε-CL). Noteblely, the prepared IL catalyst exhibited higher catalytic activity compared to solid acid catalysts duo to its behavior of reaction-induced self-separation. It meaned that the IL catalyst could switch from solid to liquid, then back to solid state during the reaction, which broke the limit of the constant heterogeneous state of the catalyst in the reaction system. The characterization results of FT-IR, 1H NMR, XRD, and XPS indicated that the phosphotungstic anion (PW12O403-) was successfully modified by the organic precursor MIMPS. And TG-DTA and Py-IR results illustrated that the catalyst possessed good thermal stability and Brønsted acidity. Furthermore, the activity evaluation experiment of the catalyst confirmed that the introduced SO3H group of the cation part and the active component tungsten of the anion part were the key to the activity of the IL catalyst. More importantly, the synergistic effect between SO3H group and the active component tungstencatalyst leading to a superior catalytic performance such as cyclohexanone conversion attained 93.51 % and the yield and selectivity of ε-CL that were up to 93.26 % and 99.73 % under the optimum conditions. Finally, the kinetic process of the BV reaction was appropriately described by the second-order reversible reaction kinetics model and the calculated results were also in good agreement with the experimental datas.

Embedding of SO3H-functionalized ionic liquids in mesoporous MIL-101(Cr) through polyoxometalate bridging: A robust heterogeneous catalyst for biodiesel production

A robust heterogeneous catalyst SIL-PW/MIL-101(Cr) for biodiesel production was fabricated via a bottom-up strategy using phosphotungstic acid (HPW) as a bridge to integrate SO3H-functionalized ionic liquid (SIL) with MIL-101(Cr). The characterization results indicated that HPW was well dispersed in the cavities of MIL-101(Cr). The subsequently introduced ionic liquid reacted with HPW to form heteropolyanion-based ionic liquid, which could be embedded in the mesoporous cages. These newly-developed SIL-PW/MIL-101(Cr) exhibited considerable catalytic activity, with 94.3 % conversion of oleic acid. The comparison experiments manifested the enhanced catalytic performance was attributed to the Brønsted acid sites originating from -SO3H groups together with the Lewis acid sites. Moreover, the mesoporous structure of MIL-101(Cr) remained intact during immobilization process, which was beneficial for diffusion of large-sized reactants. Due to the bridging function of HPW, no obvious leaching of active component during recycling was observed and the conversion maintained 91.8 % after reused for five times, displaying satisfactory reusability. This study could open new avenues for designing heterogeneous catalysts with multiple active sites through bridging strategy.

Magnetically separable heteropolyanion based ionic liquid as a heterogeneous catalyst for ultrasound mediated biodiesel production through esterification of fatty acids

The catalytic production of biodiesel has attracted the attention of academic and commercial research due to its higher efficiency and environmental sustainability. In this article, a magnetically separable heteropolyanion-based ionic liquid was synthesized, and its catalytic activity was evaluated for biodiesel production through the esterification of long-chain fatty acid under ultrasonic irradiation. The influence of different experimental parameters like amount of catalyst, the molar ratio of alcohol to acid, reaction temperature and time were evaluated. The article also describes the effect of the varying alcohols and fatty acids of different chain lengths, shapes, and unsaturation on esterification reaction. Moreover, after the reaction's completion catalyst can be easily separated from the reaction mixture through the external magnet and could be reused up to six reaction cycles without losing its catalytic efficiency.

Microwave-promoted one-pot three-component synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by heteropolyanion-based ionic liquids under solvent-free conditions

A series of 2,3-dihydroquinazoline-4(1H)-one derivatives have been synthesized via one-pot three-component reaction using isatoic anhydrides, amines and aldehydes (or ketones) catalyzed by heteropolyanion-based ionic liquids under microwave-promoted conditions. The practical protocol was found to tolerate a wide range of substrates with different functional groups. Moderate to excellent yields, solvent-free media and operational simplicity are the main highlights. Furthermore, the catalyst can be recovered and reused without evident loss of reactivity. This method provides a green and much improved protocol over the existing methods.

In situ bridging encapsulation of a carboxyl-functionalized phosphotungstic acid ionic liquid in UiO-66: A remarkable catalyst for oxidative desulfurization

This work describes a novel approach for linking metal–organic frameworks (MOFs) to polyoxometalates (POMs) for use as effective heterogeneous catalysts in the oxidative desulfurization of fuel oil. A POM-based MOF was synthesized in situ with a carboxyl-functionalized ionic liquid as a bridge to combine the POM and MOF. The resulting [mim(CH2)3COO]3PW@UiO-66 was characterized by XRD, N2 adsorption–desorption, FT-IR, SEM and TGA. The results indicated that the heteropolyanion-based ionic liquid [mim(CH2)3COOH]3PW was successfully dispersed within the cages of UiO-66. The catalyst [mim(CH2)3COO]3PW@UiO-66, which had a high content of the active component and large specific surface area, exhibited remarkable catalytic performance in oxidative desulfurization (100% DBT removal in 60 min). Importantly, a synergistic catalytic mechanism involving W = O and the Lewis acid, in which the Lewis acid promoted the decomposition of H2O2 and the generation of peroxotungstate (W(O2)n), was proposed to explain the high oxidative desulfurization catalytic efficiency of [mim(CH2)3COO]3PW@UiO-66.

Kinetics Study of the Transesterification Reaction of Methyl Acetate with Isooctyl Alcohol Catalyzed by Dicationic Heteropolyanion-Based Ionic Liquids

In this work, dicationic acidic heteropolyanion-based ionic liquids were synthesized, and used in transesterification reaction of methyl acetate with isooctyl alcohol for producing isooctyl acetate. Compared with H2SO4, and H3PW12O40, [Bis-BsImB][HPW12O40] and [Bis-Bs-DABCO][HPW12O40] shown excellent catalytic performance. The reaction kinetics and chemical equilibrium of the transesterification catalyzed by [Bis-BsImB][HPW12O40] and [Bis-Bs-DABCO][HPW12O40] were investigated. The effects of reaction temperature, initial reactant molar ratio, and catalyst concentration on the kinetics were studied in detail. The kinetic data were successfully correlated by a pseudohomogeneous model in the temperature range of 328.15 − 343.15 K. The simulation values obtained by the kinetic model were in good agreement with the experimental data. Moreover, [Bis-BsImB][HPW12O40] and [Bis-Bs-DABCO][HPW12O40] could be easily recovered and reused five times without any obvious decrease in catalytic activity.

An Efficient, Eco-friendly and Sustainable One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Directly from Alcohols Catalyzed by Heteropolyanion-Based Ionic Liquids.

Efficient, eco-friendly and sustainable access to 3,4-dihydropyrimidin-2(1H)-ones directly from alcohols under microwave and solvent-free conditions has been reported. The practical protocol involves heteropolyanion-based catalyzed oxidation of alcohols to aldehydes with NaNO3 as the oxidant followed by cyclocondensation with dicarbonyl compounds and urea or thiourea in a two-step, one-pot manner. Compatibility with different functional groups, good to excellent yields and reusable catalysts are the main highlights. The utilization of alcohols instead of aldehydes is a valid and green alternative to the classical Biginelli reaction.

Oxidative Amidation with Heteropolyanion-Based Ionic Liquids

Key words ionic liquids - tandem reaction - oxidative amidation - alcohols - amines

Catalytic Conversion of Carbohydrates to Levulinate Ester over Heteropolyanion-Based Ionic Liquids.

An efficient one-pot approach for the production of levulinate ester from renewable carbohydrates is demonstrated over heteropolyanion-based ionic liquid (IL-POM) catalysts with alcohols as the promoters and solvents. The relationships between the structure, acidic strength, and solubility of the IL-POM in methanol and the catalytic performance were studied intensively. A cellulose conversion of 100 % could be achieved with a 71.4 % yield of methyl levulinate over the catalyst [PyPS]3 PW12 O40 [PyPS=1-(3-sulfopropyl)pyridinium] at 150 °C for 5 h. This high efficiency is ascribed to the reasonably high activity of the ionic liquid (IL) catalyst and reaction coupling with rapid in situ esterification of the generated levulinic acid with the alcohol promoter, which allows the insolubility of cellulose encountered in biomass conversion to be overcome. Furthermore, the present process exhibits high feedstock adaptability for typical carbohydrates and handy catalyst recovery by a simple self-separation procedure through temperature control.

An efficient, eco-friendly and sustainable tandem oxidative amidation of alcohols with amines catalyzed by heteropolyanion-based ionic liquids via a bifunctional catalysis process

An efficient, eco-friendly and sustainable method for the tandem oxidative amidation of alcohols with amines has been reported. Using heteropolyanion-based ionic liquids as the catalyst and tert-butyl hydroperoxide as the oxidant, this amidation reaction is operationally straightforward and provides a series of primary, secondary and tertiary amides derivatives in moderate to good yields. Solvent-free media, microwave-promoted conditions and reusability of catalysts are the main highlights. Further, the proposed bifunctional catalysis mechanistic pathway has been briefly investigated in this report.

Direct oxidative amidation of aldehydes with amines catalyzed by heteropolyanion-based ionic liquids under solvent-free conditions via a dual-catalysis process.

A simple and efficient procedure for the synthesis of amides directly from aldehydes and amines catalyzed by heteropolyanion-based ionic liquids under solvent-free conditions has been reported. The practical protocol was found to tolerate a wide range of substrates with different functional groups. Moderate to excellent yields, solvent-free media, and operational simplicity are the main highlights. The proposed dual-catalysis mechanistic pathway was briefly investigated. Furthermore, the heteropolyanion-based ionic liquids were easily reusable for this oxidative amidation.

Chitosan grafted with a heteropolyanion-based ionic liquid as an effective and reusable catalyst for acetalization

Chitosan grafted with a heteropolyanion-based ionic liquid (CS–VImPS–PW) was developed via a radical addition and subsequent acidification reaction. It proved to be a green, effective and recyclable catalyst for various acetalization reactions.

Microwave-assisted heteropolyanion-based ionic liquid promoted sustainable protocol to N-heteroaryl amides via N-directing dual catalyzed oxidative amidation of aldehydes

A procedure for the synthesis of N-heteroaryl amides directly from oxidative amidation of aldehydes catalyzed by heteropolyanion-based ionic liquids has been reported. The proposed N-directing dual-catalysis mechanism was briefly investigated.

ChemInform Abstract: Microwave‐Promoted Direct Amidation of Unactivated Esters Catalyzed by Heteropolyanion‐Based Ionic Liquids under Solvent‐Free Conditions.

Abstract A simple and efficient procedure for the synthesis of amides directly from unactivated esters and amines catalyzed by heteropolyanion-based ionic liquids under microwave-promoted and solvent-free conditions has been reported. The practical protocol was found to be compatible with different structurally diverse substrates. Moderate to excellent yields, solvent-free media, and operational simplicity are the main highlights. Furthermore, the heteropolyanion-based ionic liquids were easily reusable for this amidation.

Microwave-promoted direct amidation of unactivated esters catalyzed by heteropolyanion-based ionic liquids under solvent-free conditions

A simple and efficient procedure for the synthesis of amides directly from unactivated esters and amines catalyzed by heteropolyanion-based ionic liquids under microwave-promoted and solvent-free conditions has been reported. The practical protocol was found to be compatible with different structurally diverse substrates. Moderate to excellent yields, solvent-free media, and operational simplicity are the main highlights. Furthermore, the heteropolyanion-based ionic liquids were easily reusable for this amidation.

Selective oxidation of alcohols with H2O2 catalyzed by long chain multi-SO3H functionalized heteropolyanion-based ionic liquids under solvent-free conditions

Two novel long chain multi-SO3H functionalized heteropolyanion-based ionic liquids were prepared and characterized. They as homogeneous catalysts showed high catalytic activity in selective oxidation of alcohols with 35% aqueous hydrogen peroxide under solvent-free conditions without adding any phase transfer catalyst. Two ionic liquids can be recovered readily and reused five times without any significant loss in their catalytic activities.

Efficient and Green Microwave-Assisted Multicomponent Biginelli Reaction for the Synthesis of Dihydropyrimidinones Catalyzed by Heteropolyanion-Based Ionic Liquids Under Solvent-Free Conditions

An efficient and green route for the synthesis of dihydropyrimidinones via microwave-assisted Biginelli reaction catalyzed by 3 mol% of heteropolyanion-based ionic liquids under solvent-free conditions has been reported. The practical reaction was found to be compatible with different structurally diverse substrates. Good to excellent yields, short reaction times, and operational simplicity are the main highlights of this protocol. Moreover, the heteropolyanion-based ionic liquids were easily reusable for this Biginelli reaction.

Microwave-assisted heteropolyanion-based ionic liquids catalyzed transamidation of non-activated carboxamides with amines under solvent-free conditions

An environmentally benign and highly efficient protocol for the transamidation of non-activated carboxamides with amines using heteropolyanion-based ionic liquids as catalysts under microwave-assisted and solvent-free conditions has been developed. As evaluated by the reactions of a structurally diverse set of amides and amines, the scope and utility of the transamidation proved to be quite general. Operational simplicity, solvent-free media, the potential reusability of catalysts and wide functional group tolerance are attractive features. This method provides a much improved protocol over the existing methods.

Kinetics Study of the Esterification Reaction of Diethylene Glycol Monobutyl Ether with Acetic Acid Catalyzed by Heteropolyanion-Based Ionic Liquids

Novel heteropolyanion-based ionic liquids (HPA-ILs) were obtained by combining Keggin heteropolyanions and organic cations and used as catalysts for an esterification reaction. The kinetic behaviors in the esterification of diethylene glycol monobutyl ether (DGBE) with acetic acid in the presence of HPA-ILs as catalysts were investigated systemically. Different types of HPA-ILs were used for the esterification of DGBE. Compared with H2SO4, H3PW12O40, and Amberlyst-15 resins, [BSEt3N]3PW12O40 and [BSmim]3PW12O40 exhibited excellent catalytic activities. The influences of reaction temperature, catalyst dosage, and reactant molar ratio on the conversion of DGBE were studied in detail. The kinetic data were successfully correlated by a pseudohomogeneous (PH) model in the temperature range of 343.15–363.15 K. The simulation values obtained by the kinetic model were in good agreement with the experimental data. Moreover, [BSEt3N]3PW12O40 and [BSmim]3PW12O40 could be easily recovered and reused six times without...

Heteropolyanion-based ionic liquids catalysed conversion of cellulose into formic acid without any additives

Heteropolyanion-based ionic liquids with –SO3H functionalized cations and PMo11VO404− anions were synthesized and applied in the conversion of cellulose into formic acid (FA). It was demonstrated that the as-prepared ILs showed enhanced activity for catalysing cellulose conversion to FA in the presence of oxygen in water compared to H4PMo11VO40. A high FA yield over 50% accompanied by a FA concentration of ∼10% in reaction solution was obtained at 180 °C and in an oxygen pressure of 1.0 MPa. The possible pathway of FA production from cellulose was investigated. It was indicated that the resulting ILs served as bifunctional catalysts with cations catalysing the cellulose hydrolysis to glucose and anions catalysing glucose oxidation to FA. These ILs may find more applications in cellulose conversion.