SO3H-functionalized Ionic Liquids Research Articles

Study on the reaction selectivity and hazard of m-xylene nitration catalyzed by SO3H-functionalized ionic liquids with different anions: Experimental and theoretical approaches

Five imidazole based SO3H-functionalized ionic liquids (SFILs) with different anions were selected as catalysts to achieve efficient m-xylene nitration. The acidity and thermal stability of the ILs were characterized by UV–vis and thermogravimetry. The reaction selectivity of the m-xylene nitration catalyzed by five ILs was compared. [MIMBs]HSO4 had the best catalytic activity with the maximum yield of 98.1 %. The effect of ILs on the exothermic behavior of m-xylene nitration was explored by reaction calorimeter. The reaction enthalpy (ΔH) and adiabatic temperature rise (ΔTad) were calculated to evaluate process hazards. The reaction order for the decomposition of different nitration products under adiabatic conditions was essentially close to 1. The process risk level for m-xylene nitration with the introduction of selected ILs was essentially downgraded from conditionally acceptable to acceptable, and the criticality was reduced from class 3 to 1. Furthermore, the acidic active sites of the ILs were predicted by the electrostatic potential. The solubility of m-xylene in the IL was investigated through the calculation of interaction energy. The roles of ILs as solvents and catalysts in nitration were resolved by density functional theory calculations. These findings could contribute to the understanding of the effect of ILs in modulating the process hazards and improving the selectivity of m-xylene nitration, and provide theoretical guidance for elucidating the catalytic mechanism of ILs in nitration.

Structures and hydrogen bonds of -SO3H functionalized acid ionic liquids

Brønsted acidic ionic liquids (BAILs) are clean and versatile replacements for traditional homogeneous acid catalysts and have attracted much attention as efficient catalysts for the synthesis of valuable chemicals. It’s critically important to understand the structural properties of BAILs from the molecular level. In this work, we studied a series of −SO3H functionalized acidic ionic liquids by density functional theory (DFT) calculations, and the most stable geometries were obtained by global semiempirical quantum mechanical search. The most stable structures of cations are formed when more intramolecular H-bonds exist. For BAILs clusters, intramolecular and intermolecular H-bonds coexist and play a critical role in the stability of the system. The interaction energy decreases with increasing alkyl chain length. When the alkyl chain was replaced by −SO3H groups, the interaction energy increased due to more H-bonds formed with the anions. The quasi-3D network is formed in the BAILs clusters and the electrostatic interaction plays a critical role in stabilizing the ion clusters. This work helps to understand the microcosmic interactions of BAILs in-depth and design them in a “task-specific” way.

One-pot directly conversion of passion fruit husk to levulinic acid using highly efficient and recyclable SO3H-functionalized ionic liquids

In this study, hydrothermal conversion of passion fruit husk powder (PFHP) into levulinic acid (LA) was achieved using SO3H-functionalized ionic liquids (ILs) as catalyst. The investigation focused on the impact of IL types and reaction conditions (temperature, time, water quantity and catalyst loading) on LA yield. Among the selected ILs, [C4SO3Hmim][HSO4] exhibited the highest LA yield at 66.6%, achieved under specific conditions: 4 h of reaction time, 180 °C temperature, 0.2 g of PFHP, 1.5 g of IL, and 6.0 g of deionized water. Remarkably, [C4SO3Hmim][HSO4] displayed consistent stability and catalytic efficiency throughout four recycling cycles. Comprehensive analyses, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD), were conducted on the solid residues of passion fruit husk obtained at different reaction times. These analyses revealed significant alterations in surface morphology, functional groups, and crystallinity index of the solid residues with prolonged reaction times. Notably, hemicellulose and lignin removal occurred within the first 0.5–1 h of the reaction, leading to the formation of by-products after 3 h. This one-pot process for LA production from agricultural waste showcases a promising avenue for converting sustainable biomass resources into valuable chemicals, emphasizing the potential for future biomass utilization.

Highly active sulfonic ionic liquid modified heteropoly acid composite catalysts for efficient production of ethyl palmitate

Highly active inorganic-organic composite catalysts were synthesized by incorporating Keggin-type tungstophosphoric acid (H3PW12O40; HPW) with SO3H-functionalized ionic liquids (SFILs), which were prepared by integrating chloromethylated polystyrene (CP) resin, piperazine (PI) and 1.3-propane sultone, as primary sources. The [CPPI-SO3H]nH3−nPW12O40 (n = 1.0–3.0) catalysts were characterized by XPS, SEM, FT-IR, XRD, TG-DTA, TEM, and solid-state 31P MAS NMR. These HPW-SFIL composite catalysts were found to be highly stable and possess ultra-strong Brønsted acidity, desirable self-separation properties, and catalyst reuse for production of biodiesels through esterification of palmitic acid (PA) and ethanol (EtOH). On the basis of the Box-Behnken design (BBD), further process optimization using response surface methodology (RSM) over the [CPPI-SO3H]2.0H1.0PW12O40 catalyst led to the optimized experimental conditions: EtOH/PA = 7.7 mol/mol, catalyst amount = 4.4 wt%, reaction time = 2.5 h, reaction temperature = 363 K, accompanied by an ethyl palmitate yield of 97.2%, in excellent agreement with the predicted value. The catalyst was highly stable, retaining a 94.7% yield after six consecutive running cycles. Moreover, a kinetic study performed under optimal reaction conditions revealed an apparent reaction order of 1.40 and an active energy of 14.80 kJ mol−1.

Design and synthesis of SO3H-functionalized acidic ionic liquids for catalytic conversion of wheat straw to ethyl levulinate

Ethyl levulinate (EL) is a key platform compound for the catalytic conversion of biomass. Ionic liquids (ILs) have attracted much attention due to their unique tunable structures and wide range of applications, a series of SO3H-functionalized imidazole based acidic ILs were designed and synthesized. These SO3H-functionalized ILs were used as the catalyst to be applied to the conversion of the wheat straw to EL. Among them, SimIL-6 exhibited good catalytic performance for the conversion of wheat straw to EL in ethanol. When the concentration of SimIL-6 was 30 mmol/L, the yield of EL could reach 20.1 wt% at 180 ℃ for 2 h. Furthermore, SimIL-6 as the catalyst was reused at least six times without significant reduction in catalytic efficiency. This work shed light on a new approach towards the full utilization of biomass and efficient degradation of biomass to EL.

Regulating the Acidity of SO3 H-Functionalized Ionic Liquids: Hydrogen Bonding or Electrostatic Potential?

The SO3 H-functionalized ionic liquids (ILs) with high acidity are important catalysts for acid-catalyzed reactions. However, the acidity of these ILs have been found to decrease due to intramolecular hydrogen bonds (H-bonds). In this work, a series of anionic SO3 H-functionalized ILs were designed and the factors resulting in weak acidity were investigated, including H-bonds strength and electrostatic potential on the leaving proton (ESPLP). Using catalytic experiment, atoms in molecules topology analysis and electrostatic potential calculation, it was found that the acidity of ILs was correlated with the value of ESPLP rather than the H-bond strength. Meanwhile, there were several ways to increase the acidity of anionic SO3 H-functionalized ILs, such as enhancing the electron-withdrawing ability of cation, introducing H-bond acceptor sites on cation or separating the intramolecular H-bonds through substitution position. These strategies made the conversion of TBA in Friedel-Crafts alkylation increase from 19 % to 84 %.

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.

Direct conversion of cellulose to levulinic acid using SO3H-functionalized ionic liquids containing halogen-anions

The conversion of cellulose to levulinic acid (LA) and other platform chemicals is a promising route to solve the energy crisis. For this purpose, a series of new SO3H-functionalized ionic liquids (ILs), containing different halogen-anions were synthesized and applied for catalytic conversion of cellulose to LA. The structure, thermal stability, and acidity of SO3H-functionalized ILs were characterized by Nuclear magnetic resonance (NMR) spectra, Fourier-transform infrared (FT-IR), High resolution mass spectrometry (HRMS), thermogravimetric analysis (TGA), and Hammet acidity method. The results revealed that as the size of halogen anions increased, the Hammett acidity gradually increased from SO3H-functionalized ILs containing fluorine- to chlorine- and then to bromine-anions. When SO3H-functionalized ILs were used as a catalyst for the production of LA from cellulose, the yield of LA gradually increased as the size of halogen-anions increased from fluorine- to chlorine- and then to bromine-anions. Among the SO3H-functionalized ILs, 1,1-bis(3-(4-sulfobutyl)imidazolium-1-yl)butylene bromine ([BSim]Br) exhibited the best catalytic activity with 76.5% yield of LA in cellulose/[BSim]Br/H2O (m/m/m = 1:9:8) reaction system at 180 °C for 20 min, which was the highest yield compared to previous literature reports using ILs as catalyst. Besides, the [BSim]Br was easily recovered and showed high catalytic activity after five cycles. The efficient catalyst, [BSim]Br is then proposed to have a great potential for mass production of LA from biomass.

PH of Single and Double Salt SO3H-Functionalized Brønsted Acidic Ionic Liquids

Acidic ionic liquids are widely utilized as catalysts in acid-catalyzed reactions. The acidity of SO3H-functionalized Bronsted acidic ionic liquids (S-BAILs) in aqueous solutions was systematically...

Selective monoalkylation of hydroquinone in the presence of SO3H-functionalized ionic liquids as catalysts

A process aiming at O-alkylation of hydroquinone (HQ), where ionic liquids (ILs) act as catalyst is objectively described. Five SO3H-functionalized ILs having different cations were prepared and characterized by NMR and FTIR techniques. The acidity and thermal stability of ILs were determined by Hammett function and thermogravimetric analysis (TGA), respectively. The catalytic activity of these ILs were tested for O-alkylation of HQ with methanol in 4-methoxyphenol (4MP) in the presence of small amount of benzoquinone (BQ). The effect of reaction parameters such as temperature, time, catalyst loading and substrate concentration on the conversion of HQ and product distribution was examined and optimized to maximize the yield of 4MP using 1,3-disulfonic acid imidazolium hydrogen sulfate (IL2) catalyst. Maximum yield of desired product 4MP 93.79% was obtained at 338 K temperature, 5.45 × 10–2 mol HQ, 8.33 × 10–3 mol BQ, and 10.37 mol% catalyst loading in 120 min reaction time. Single-product formation was observed up to 338 K temperature but higher temperature (above 338 K) and longer reaction time resulted in the formation of 2,4-dimethoxyphenol (24DMP) as a by-product. Catalyst recyclability was also established up to the fifth run which showed no declination in its activity.

Hydrogen Bonds in Disulfonic-Functionalized Acid Ionic Liquids for Efficient Biodiesel Synthesis.

Regulating the states of hydrogen bonds in ionic liquids (ILs) is an effective way to improve their catalytic performance. In this paper, disulfonic-functionalized acidic ionic liquids (DSFAILs) were synthesized successfully, including novel SO3H-functionalized binuclear IL (bis[3-(CH2)3SO3H-1-(CH2)2-Im][HSO4]2). For the biodiesel synthesis, compared with the traditional ILs catalysts, DSFAILs bis[(3-(CH2)3SO3H-1-(CH2)2-Im][HSO4]2, [Im(N (CH2)3SO3H)2][HSO4]) had higher catalytic activity even under mild reaction conditions. Using the density functional theory (DFT) method, the role of hydrogen bonds in different SO3H-functionalized acidic ionic liquids (SFAILs) was explored. The forms of hydrogen bonds existing in different ILs directly determine their acidity. It suggested that the forming status of the active sites (hydrogen bonds) were diverse in different SFAILs. Also, deep ionization of the hydrogen atoms from the cation–anion strong interaction could increase the acidity and catalytic performance of SFAILs. From this, the structure–activity relationship between the SFAILs structures and the catalytic activity of methyl oleate synthesis was proposed. Besides, the experimental results also showed that bis[3-(CH2)3SO3H-1-(CH2)2-Im][HSO4]2 catalyst had a high catalytic activity to obtain methyl oleate and the catalyst could be separated easily owing to its larger molecular weight. However, [Im(N(CH2)3SO3H)2][HSO4] had a stronger acidity and a lower steric hindrance and thus a higher catalytic activity and was the optimal catalyst for the methyl oleate synthesis. In the presence of a small amount of catalyst (6 wt %) and at low reaction temperature (353 K), the methyl oleate yield could reach up to 93%. After six recycles of the catalyst, the methyl oleate yield remained at 90%.

Novel SO3H-functionalized polyoxometalate-based ionic liquids as highly efficient catalysts for esterification reaction

Three novel heteropolyanion-based Brønsted acidic ionic liquids (BAILs), butane mono sulfoacid-functionalized 1,10-phenanthrolinum, butane mono and bis sulfoacid-functionalized 1,4-dimethylpiperazinium salts of phosphortungstate catalyst (PhBs1-PW, [PipBs1]3-PW and [PipBs2]3-(PW)2) were synthesized and well characterized with FTIR, 1H and 13C NMR, Electro-Spray Ionization Mass Spectrometry (ESI-MS), Elemental analysis (CHNS), EDX and TG analysis techniques. The esterification reactions of monocarboxylic acids with monohydric alcohols were carried out using these catalysts. The introduced catalysts present a self-separation performance after reaction, which can be easily recovered and quite steadily reused as confirmed by six-run recycling test. Moreover, bis sulfoacid-functionalized 1,4-dimethylpiperazinium salt of phosphortungstate showed the best catalytic performance among the prepared catalysts for the esterification reaction.

Thermokinetics of SO3H-functionalized dicationic ionic liquids: Effect of anions

In this study, the kinetics of thermal degradation of three ionic liquids (ILs) were investigated using non-isothermal thermogravimetric analysis to investigate the thermal stability of ILs with various anion. Di(4-sulfonic acid) dibutyltriethylene diammonium di(hydrogen sulfate, ([DABCODBS][HSO4]2), di(4-sulfonic acid) dibutyltriethylene diammonium di(trifluoromethanesulfonate) ([DABCODBS][CF3SO3]2) and di(4-sulfonic acid) dibutyltriethylene diammonium di(chloride) ([DABCODBS][Cl]2) were subjected to thermogravimetric analysis (TGA) in the temperature range of 50-800°C at four heating rates of 10, 15, 20 and 25°C/min using nitrogen at a flow rate of 20 L/min as purge gas. The average activation energies (Ea) calculated using Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO) and Starink methods are 163.49, 173.33 and 162.58 kJ/mol for [DAB CODB S][HSO4]2, 119.59, 130.41 and 119.07 kJ/mol for [DABCODBS][CF3SO3]2, and 199.72, 210.50 and 198.63 kJ/mol for [DABCODBS][Cl]2, respectively. The results presented through all kinetic methods are in close agreement with each other and showed a decreasing thermal stability trend of [DABCODBS][Cl]2 > [DABCODBS][HSO4]2 > [DABCODBS][CF3SO3]2. The results also showed that intermediates were formed for [DABCODBS][CF3SO3]2 and [DABCODBS][HSO4]2 until achieved total decomposition, while there was no intermediate formed for the pyrolysis kinetic of [DABCODBS][Cl]2. This study shows the effect of nature of anion towards the thermal stability and decomposition mechanism of ILs.

Understanding Structure–Property Relationship of SO3H-Functionalized Ionic Liquids together with Sulfuric Acid in Catalyzing Isobutane Alkylation with C4 Olefin

In this work, the SO3H-functionalized ionic liquids (SFILs) ([CnPSIm][HSO4], n = 1, 2, 4, 6, and 8) were investigated as cocatalyst mixed with the concentrated H2SO4 for the isobutane alkylation. The SFILs with longer alkyl chain show a better catalytic performance with the C8 selectivity up to 75.73 and RON up to 95.66, respectively. The better catalytic performance can be attributed to the better dispersion of isobutane in the SFIL/H2SO4 system led by the SFILs with longer alkyl chain, which is further correlated with the nanostructured-aggregation feature of the longer alkyl chain confirmed by MD simulation. In addition, the reusability of SFIL/H2SO4 mixture can reach up to 22 runs, outclassing the pure H2SO4. The MD simulation, quantum chemistry calculations, and 1H NMR spectra revealed that cationic clusters are formed by the strong hydrogen bonds between the sulfonic acid group and the H2SO4, which is beneficial to the longer lifetime of the SFIL/H2SO4 mixtures. Hopefully, the useful information in ...

Efficient and reusable zeolite-immobilized acidic ionic liquids for the synthesis of polyoxymethylene dimethyl ethers

A series of molecular sieve-immobilized Brønsted acidic ionic liquids (BAILs@MS) was prepared, characterized and utilized as efficient catalysts for the synthesis of polyoxymethylene dimethyl ethers (PODEn or DMMn) from methylal (DMM1) and trioxane (TOX). Combined characterization results from fourier transform infrared (FT-IR) spectroscopy, elemental analysis, thermogravimetry (TG), N2 adsorption-desorption (Brunauer-Emmett-Teller, BET) isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM) and temperature-programmed desorption of ammonia (NH3-TPD), suggested that the synthesized BAILs were successfully immobilized on the surface of molecular sieves through covalent bonds. Moreover, the catalytic performance tests demonstrated that NaZSM-5 immobilized SO3H-functionalized ionic liquids (ILs) i.e., BAILs@NaZSM-5, exhibited excellent activity for the acetalation of DMM1 with TOX, compared to the homogeneous catalysis of the precursors ([MIMBs]HSO4) as well as other molecular sieve-supported ILs. The influence of catalyst concentration, molar ratio of DMM1 to HCHO, temperature and reaction duration on the catalytic activity were investigated by employing [NaZSM-5IMBs]HSO4 as the catalyst. It was demonstrated that a superior conversion of formaldehyde (FA) (90.3%) and excellent selectivity for DMM3-8 (53.5%) has been achieved in mild conditions (110 °C, 2.5 MPa for 2 h). Additionally, the catalyst can be effortlessly separated by filtration and reused more than ten times without significant loss of activity.

Synthesis of raspberry ketone via Friedel-Crafts alkylation reaction catalyzed by sulfonic acid-functional ionic liquids

Phenol and butanolone catalyzed by different SO3H-functionalized ionic liquids (ILs) for synthesis of raspberry ketone (RK) had been investigated. The influences of different ionic liquids, reaction time, reaction temperature, reactant ratio, the amount of ionic liquid were investigated. The yield of raspberry ketone was 82.5% under the optimum reaction condition. In addition, the ILs (3-sulfo)propyltriamine bisulfate ([TEA-PS][HSO4]) can be recycled up to five consecutive times without loss of activity. This method had the advantages of mild conditions, high product yield, easy to separate from the product, as well as environmentally friendly procedure. At the same time, the possible reaction mechanism was discussed.

Novel SO3H-functionalized dicationic ionic liquids – A comparative study for esterification reaction by ultrasound cavitation and mechanical stirring for biodiesel production

Abstract This present article covers a comparative study of esterification reaction using either ultrasound cavitation or conventional mechanical stirring with a series of newly developed SO 3 H-functionalized dicationic ammonium- and DABCO-based acidic ionic liquids. As a baseline for performance evaluation, esterification reaction was also conducted with a series of SO 3 H-functionalized monocationic ammonium-based acidic ionic liquids and several conventional mineral acids (H 2 SO 4 , etc.). Their efficacy as catalyst towards perceptive esterification for the synthesis of biodiesel from free long-chain fatty acids with methanol were appraised. The Hammett acidity of these conventional acids and acidic ionic liquids were also assessed using UV–visible spectroscopy. Four factors were studied in the process of optimizing the reaction conditions, which are methanol to oil molar ratio (3–15), catalyst amount (0.2–1.0%), temperature (25–60 °C) and time (0–60 min). Whereas esterification under mechanical stirring leads to formation of a triphasic system (methanol, ionic liquids and esters) easing final separation of components, the same reaction under ultrasonic irradiation leads to formation of one phase layer at the end of reaction but the esters were simply isolated using centrifugation. The results showed that whatever ultrasound or mechanical stirring, the use of dicationic ionic liquids authorized better conversion yields of free fatty acid (FFA) into fatty acid methyl esters (FAME) with better yields than with either monocationic ionic liquids or mineral acids. The novel ionic liquids together with the design of a clean procedure offers advantages including short reaction time, good yield, operational simplicity, and environmentally benign characteristics.

Fast Synthesis and Antibacterial Evaluation of Benzimidazo[2,1-b]quinazolin-1-ones: Another Successful Application of Newly Prepared SO3H-Functionalized Ionic Liquids as Catalysts

Structures containing the two active pharmacophores benzimidazole and quinazoline, either alone or as fused rings with other heterocyclic moieties, have attracted organic chemists because of their ...

Design and Exploration of –SO3H Group Functionalized Brønsted Acidic Ionic Liquids (BAILs) as Task-Specific Catalytic Systems for Organic Reactions: A Review of Literature

For several decades various chemical industries are involved in environment pollution by using hazardous chemicals or excessive use of solvents or catalysts to get maximum amount of desired product. In this case acidic ionic liquids may act as safer substitute of volatile organic solvents/or traditional Bronsted or Lewis acid catalysts with their unique dual task-specific solvent-catalyst properties. Recent surge in the literature review clearly describes the importance, properties and applications of acidic ionic liquids as solvent and efficient reusable catalyst in organic reactions. This review presents an account of some recent reports indicating the synthesis and uses of –SO3H functionalized ionic liquids(SFILs) as catalyst in organic synthesis.

Acidic ionic liquids and green and recyclable catalysts in the clean nitration of TAIW to CL-20 using HNO3 electrolyte

A novel method for the synthesis of CL-20 by nitration of TAIW was investigated. HNO3 electrolyte, containing generated dinitrogen pentoxide and unreacted dinitrogen tetraoxide, was directly used as a nitrating agent and the result was encouraging. A series of SO3H-functionalized ionic liquids were utilized to further improve the result. The satisfactory yield of CL-20 (94%) makes it a useful method for the green and clean synthesis of CL-20.