SO3H-functionalized Ionic Liquid Research Articles

Molecular design of efficient SO3H-functionalized ionic liquid to catalyse chitin into levulinic acid: NMR and DFT study

Although chitin is the second abundant natural biomass after cellulose, investigations on chitin conversion are still limited. Levulinic acid (LA) is versatile biorefinery platform chemical. The SO3H-functionalized ILs present excellent catalytic activity to transfer biomass into LA. To improve the yield of LA and select the IL with higher catalytic activity, the relationship between the structure of SO3H-functionalized ILs and their catalytic capacities for LA production from chitin are explored with the 1H NMR and density functional theory (DFT) methods in this work. First, the catalytic activities of the selected ILs were predicted by the DFT methods. Then, they were confirmed by the 1H NMR experiments. The order of the catalytic activity of the ILs for chitin conversion into LA is consistent with the sequence of the gap of the LUMO-HOMO of the most stable IL- N-acetylglucosamine (NAG) complexes. The imidazolium-based ILs show the best catalytic activity, followed by the pyridinium-based and ammonium-based ILs. The ILs with butyl chain have stronger catalytic activity than those with propyl chain. Based on the 1H NMR and DFT results, the [C4SO3Hmim]HSO4 was selected to catalyse chitin conversion into LA. The maximum yield of LA is 74.7 % achieved at 5 h reaction time, 190 ℃, 6.0 g water, 1.5 g [C4SO3Hmim]HSO4 catalyst and 0.1 g chitin.

Conversion of cellulose into levulinic acid under the catalysis of Brønsted acidic ionic liquid and erbium chloride in water

We propose a new approach for the synergistically catalytic conversion of cellulose to levulinic acid (LA) in water by SO3H-functionalized ionic liquid (SFIL) and lanthanide chloride (LnCl3). Compared with using 1-methyl-3-(3-sulfopropyl)imidazolium chloride ([MIMPS]Cl) only, the LA yield using [MIMPS]Cl and ErCl3 increased by 14.4% and 13.6% at 50 mol% of IL and 30 mol% of IL, respectively. Moreover, the combined [MIMPS]Cl and ErCl3 system can tolerate high concentrations of substrates and maintain high activity at eleven runs. We also investigated the effects of the cation structure of ionic liquids (alkyl chain length, hydroxyl groups on the side chains, and aromatic properties) on LA production. The observations can provide useful information for designing efficient ionic liquid catalysts for biomass utilization.

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.

Process Intensification of 2,2'-(4-Nitrophenyl) Dipyrromethane Synthesis with a SO3H-Functionalized Ionic Liquid Catalyst in Pickering-Emulsion-Based Packed-Bed Microreactors.

A stable water-in-oil Pickering emulsion was fabricated with SO3H-functionalized ionic liquid and surface-modified silica nanoparticles and used for 2,2′-(4-nitrophenyl) dipyrromethane synthesis in a packed-bed microreactor, exhibiting high reaction activity and product selectivity. The compartmentalized water droplets of the Pickering emulsion had an excellent ability to confine the ionic liquid against loss under continuous-flow conditions, and the excellent durability of the catalytic system without a significant decrease in the reaction efficiency and selectivity was achieved. Compared with the reaction performance of a liquid–liquid slug-flow microreactor and batch reactor, the Pickering-emulsion-based catalytic system showed a higher specific interfacial area between the catalytic and reactant phases, benefiting the synthesis of 2,2′-(4-nitrophenyl) dipyrromethane and resulting in a higher yield (90%). This work indicated that an increase in the contact of reactants with catalytic aqueous solution in a Pickering-emulsion-based packed-bed microreactor can greatly enhance the synthetic process of dipyrromethane, giving an excellent yield of products and a short reaction time. It was revealed that Pickering-emulsion-based packed-bed microreactors with the use of ionic liquids as catalysts for interfacial catalysis have great application potential in the process of intensification of organic synthesis.

Novel SO3H-functionalized phenanthrolinum-phosphotungstate ionic liquid for highly promoted three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones

A novel heteropolyanion-based Bronsted acidic ionic liquid material [PhBS]3PW12O40, butane mono-sulfoacid-functionalized phenanthrolinum salt of phosphortungstate catalyst (PhBS-PW), was synthesized and well characterized with FTIR, 1H and 13C NMR, electro-spray ionization mass spectrometry (ESI-MS), EDX and TG analysis techniques. The new prepared catalyst was used for the efficient one-pot synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives from a three-component condensation reaction between aromatic aldehydes, dimedone, and phthalhydrazide in H2O under thermal conditions. This green approach has several advantages such as short reaction times, clean reaction profiles, and simple experimental and workup procedures. Moreover, the catalyst can be easily recovered and reused at least nine times with only slight reduction in its catalytic activity with no leaching amount of catalyst into the reaction mixture. These economical factors (time, cost, waste, etc.) for this three-component reaction hold promise for the future of organic synthesis. In this work we introduced a new efficient Bronsted acidic ionic liquid (BAIL) and then its catalytic activities have been considered in the three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones via the domino Knoevenagel condensation/Michael addition/intramolecular cyclodehydration sequence in water under reflux condition.

Condensation of 9-fluorenone and phenol using an ionic liquid and a mercapto compound synergistic catalyst

A SO3H-functionalized ionic liquid and thiol co-catalyst synergistically catalyze the condensation reaction of 9-fluorenone with phenol.

Mechanistic insight into β‒O‒4 linkage cleavage of lignin model compound catalyzed by a SO3H-functionalized imidazolium ionic liquid: An unconventional E1 elimination

Efficient liquefaction of lignin has been realized by using 1-methyl-3-(3-sulfopropyl)-imidazolium hydrogensulfate [C3SO3HMIM][HSO4] ionic liquid (IL) as catalyst (Green Chem. 18 (2016) 4098–4108). To gain insight into the mechanism of the catalytic cleavage of the dominant linkage (β−O−4 linkage) in lignin, a DFT study has been performed on the β‒O‒4 linkage cleavage of the lignin model compound, veratrylglycerol-β-guaiacyl ether (VG). The calculated energetically viable pathway consists of five stages: (1) protonation-dehydration, (2) β-H elimination, (3) protonation, (4) hydroxylation, and (5) β−O−4 bond cleavage. The initial deprotonation-dehydration process with a free energy barrier of 29.7 kcal/mol is identified as the bottleneck step. Throughout all elementary steps, both the cation and anion of the IL are found to play substantial roles. The cation acts as a Brønsted acid, while the counteranion plays a dual role of Brønsted base and proton shuttle. The identified mechanism refers to an unconventional E1 elimination, which preferably leads to a (Z)-olefin derivative, i.e. (Z)-enol-ether, rather than its (E)-isomer. Distortion/interaction analysis demonstrated that the deformation of the VG moiety, which is induced by the orbital interaction between the developing sp2 hybridized Cβ atom and the β-O atom, controls the stereoselectivity of the E1 elimination. Our study provides detailed mechanistic insights for the cleavage of β−O−4 linkage in lignin promoted by [C3SO3HMIM][HSO4] IL, and guides the design of efficient functionalized imidazolium IL catalysts for lignin depolymerization.

Anionic SO3H-functionalized ionic liquid: An efficient and recyclable catalyst for the Pechmann reaction of phenols with ethyl acetoacetate

ABSTRACTThis paper has reported an anionic SO3H-functionalized ionic liquid N-methylimidazolium sulfomethylsulfonate ([Hmim][HO3SCH2SO3]) for the synthesis of coumarins by Pechmann reaction. The [Hmim][HO3SCH2SO3] is easier to prepare by one-step neutralization reaction of N-methylimidazole with methanedisulfonic acid and show high catalytic performance for Pechmann reaction. Besides, the catalyst can simply be separated from the reaction mixture and recycled ten times without noticeable loss of activity.

A green and practical method for the synthesis of novel pyrano[2,3-c]pyrazoles and bis-pyrano[2,3-c]pyrazoles using sulfonic acid-functionalized ionic liquid

An efficient and practical protocol was developed for the synthesis of novel pyrano[2,3-c]pyrazoles and bis-pyrano[2,3-c]pyrazoles by one-pot four-component reaction of arylaldehyde, ethyl acetoacetate, hydrazine hydrate and dimethyl malonate using SO3H-functionalized ionic liquid [DMBSI]HSO4 as a potential green catalyst under solvent-free condition. The method presented is mild, environmentally friendly, inexpensive and functionality tolerant and produces the desired pyranopyrazoles in short reaction times (17–24 min) and excellent yields (85–95%). In addition, the catalyst can be reused at least ten times without almost any change in its catalytic activity.

Conversion of C5 Carbohydrates into Furfural Catalyzed by SO3H-Functionalized Ionic Liquid in Renewable γ-Valerolactone

To obtain an efficient and green reaction system for the production of furfural (FF), this study investigated the use of a SO3H-functionalized ionic liquid as a catalyst for the conversion of xylose in a solvent of renewable γ-valerolactone (GVL). A high FF yield of 78.12% was obtained in this reaction system catalyzed by 1-propylsulfonic-3-methylimidazolium chloride at 140 °C. The GVL remarkably enhanced the reaction rate and increased the xylose conversion and FF yield because the solvent effect of GVL could improve the catalytic activity of the acidic protons and suppress the side reactions. In addition, the ionic liquids showed satisfactory catalytic performance in the conversion of xylose to FF due to functionalization by introducing a SO3H group. The conversion of other C5 carbohydrates (arabinose and xylan) was also tested in this system, and moderate FF yields were achieved.

A theoretical elucidation: why does a SO3H-functionalized imidazolium-based ionic liquid catalyze the conversion of 5-hydroxymethylfurfural to levulinic acid?

DFT calculations show a clear picture of how a SO3H-functionalized imidazolium-based ionic liquid catalyzes the conversion of 5-HMF to LA.

Synthesis of cellulose-derived carbon dots using acidic ionic liquid as a catalyst and its application for detection of Hg2+

Carbon dots (CDs) as versatile carbon-based nanomaterials have attracted increasing attention because of their non-toxicity, good water solubility and photostability, and easy surface functionalization. For their wide application, it is still needed to explore moderate and facile methods for synthesizing CDs from green and inexpensive precursors. In this paper, a moderate method was developed to synthesize water-soluble CDs by ionothermal treatment of cellulose with SO3H-functionalized acidic ionic liquid as a catalyst in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The preparation process was carried out at relatively low temperature in non-pressurized vessel. The synthesized CDs exhibit near-spherical morphology with an average diameter of 8.0 nm, and the surface is carbon and oxygen rich. The CDs have powder-blue fluorescence with excitation-dependent emission behavior and excellent stability. Moreover, the as-prepared CDs were demonstrated as an effective “turn-off” fluorescent probe for the selective detection of Hg2+ with a good linear relationship over the concentration range from 6 to 80 μM. The application of acidic ionic liquid should provide a new path for the synthesis of CDs under mild condition.

ChemInform Abstract: Novel SO3H‐Functionalized Ionic Liquids — Catalyzed Facile and Efficient Synthesis of Polyhydroquinoline Derivatives via Hantzsch Condensation under Ultrasound Irradiation.

A facile and efficient synthesis of polyhydroquinolines has been developed via four-component condensation reactions of aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate in the presence of Novel SO3H-functionalized ionic liquid catalysts through Hantzsch reaction under ultrasound irradiation without solvent. Simple work-up procedure, environmentally friendly, inexpensive, and non-toxic catalyst, shorter reaction times along with excellent product yields are the significant features of this practical method.

A novel hydroxylamine ionic liquid salt resulting from the stabilization of NH2OH by a SO3H-functionalized ionic liquid.

A SO3H-functionalized ionic liquid was used as an alternative to conventional inorganic acids in hydroxylamine stabilization, leading to the formation of a novel hydroxylamine ionic liquid salt that exhibits improved thermal stability and reactivity in the one-step, solvent-free synthesis of caprolactam in comparison with hydroxylamine hydrochloride and hydroxylamine sulfate.

An efficient and ecocompatible synthesis of annulated benzothiazoloquinazolines in SO3H-functionalized ionic liquid

Structurally diverse annulated benzothiazoloquinazolines have been synthesized by an environmentally benign, efficient, and convenient synthesis involving three-component domino reaction of 2-aminobenzothiazoles, α-tetralone, and furan-2-carbaldehyde/p-methoxybenzaldehyde using an SO3H-functionalized halogen-free ionic liquid ([MIM(CH2)4SO3H][HSO4]) as a catalyst and a reaction medium.

Clean Procedure for the Synthesis of α-Aminophosphonates Catalyzed by Biodegradable Ionic Liquid

A biodegradable SO3H-functionalized ionic liquid (IL) was prepared and used as the catalyst for a one-pot, three-component condensation synthesis of α-aminophosphonates from aldehydes, amines, and triethylphosphite/diethylphosphite at room temperature under solvent-free conditions or in aqueous media. The products could be simply separated from the reaction mixture and the catalyst could be recycled and reused for several times without noticeably reducing catalytic activity.

Facile Biodiesel Synthesis from Esterification of Free Fatty Acids Catalyzed by SO3H-Functionalized Ionic Liquid

Facile Biodiesel Synthesis from Esterification of Free Fatty Acids Catalyzed by SO3H-Functionalized Ionic Liquid

Synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones catalyzed by biodegradable ionic liquid

A biodegradable acyclic SO3H-functionalized ionic liquid has been used as a novel catalyst for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones via one-pot multi-component condensation of β-naphthol, aromatic aldehydes, and cyclic 1,3-dicarbonyl compounds, under solvent-free conditions, to afford good to excellent yields ranging from 85 to 93 % within 30–60 min. After the reaction the products could be simply separated from the reaction mixture and the catalyst could be recycled and reused several times without noticeable reduction of catalytic activity.

Use of SO3H-functionalized halogenfree ionic liquid ([MIM(CH2)4SO3H] [HSO4]) as efficient promoter for the synthesis of structurally diverse spiroheterocycles

Structurally diverse spiroheterocycles with fused systems incorporating medicinally privileged systems have been synthesized by an efficient and convenient synthetic method involving four component domino reaction of 2-aminobenzothiazoles with isatin and cyclic β-diketones using SO3H-functionlized halogenfree ionic liquid ([MIM(CH2)4SO3H][HSO4]) in aqueous medium.

A novel Brønsted acidic heteropolyanion-based polymeric hybrid catalyst for esterification

Abstract A new SO3H-functionalized HPA-based acidic polymeric hybrid was prepared by coupling task-specifically designed SO3H-functionalized polymeric ionic liquid with Keggin-structured heteropolyanion, and characterized by 1H NMR, FT-IR, TG, XRD, BET, Hammett indicator, melting point, and elemental analysis. Its catalytic performance for esterification of alcohols with carboxylic acids was studied under solvent-free conditions. The results demonstrate that the polymeric hybrid is a highly active and selective solid catalyst for various esterifications, and can be easily recovered and steadily reused.