Palladium-catalyzed hydroesterification of olefins with isosorbide in standard and Brønsted acidic ionic liquids

The palladium catalyzed hydroesterification of 1-octene with isosorbide was studied in standard and Brønsted acidic ionic liquids as reaction media. High conversions and selectivities towards the targeted isosorbide diesters have been achieved by using a catalytic system composed of Pd(OAc)₂ and trisulfonated triphenylphosphine dissolved in 1-(4-sulfonic acid)-butyl-3-methylimidazolium tosylate. The catalytic phase can be reused several times without any significant decrease in activity and selectivity.     

Transesterification of soybean oil to biodiesel by tin-based Brønsted-Lewis acidic ionic liquid catalysts

A series of Brønsted-Lewis acidic ionic liquid (BLAIL) catalysts consisting of sulfonated ionic liquid [SO₃H-pmim]Cl and Sn(II) chloride have been synthesized and exploited for catalytic transesterification of soybean oil with methanol to biodiesel. The structural and chemical properties of these [SO₃H-pmim]Cl-xSnCl₂ (x=0-0.8) catalysts were characterized by different analytical and spectroscopic techniques, such as FT-IR, TGA, and NMR. In particular, their acid properties were studied by solid-state ³¹P NMR using trimethylphosphine oxide as the probe molecule. The BLAIL catalysts were found highly efficient for transesterification reaction due to the introduction of Lewis acidity by SnCl₂ in the initially Brønsted acidic [SO₃H-pmim]Cl catalyst. The effects of three independent process variables on biodiesel yield were optimized by response surface methodology (RSM). Consequently, an excellent biodiesel yield of 98.6% was achieved under optimized reaction conditions over the BLAIL catalyst with SnCl₂ loading (x) of 0.7.     

Synthesis of a silica-immobilized Brönsted acidic ionic liquid catalyst and hydrolysis of cellulose in water under mild conditions

A silica immobilized imidazolium-type acidic ionic liquid catalyst was shown to be a better catalyst than n-propylsulfonic acid silica (PrSO₃H-SiO₂) and sulfonic acid silica (SO₃H-SiO₂) for the hydrolysis of untreated Sigmacell Cellulose (DP ~ 450) in water. For example, new catalyst produced the highest TRS yield of 48.1% after 3 h at 190 °C, whereas cellulose samples heated with PrSO₃H-SiO₂ and SO₃H-SiO₂ catalysts produced only 19.9% and 13.2% TRS yields, respectively, under identical conditions. The new catalyst could be recycled up to four cycles with a small loss in catalytic activity.     

Study on extraction of thiophene from model gasoline with br?nsted acidic ionic liquids

Br?nsted acidic ionic liquids (ILs), N-methylimidazole hydrogen sulfate ([HMIm]HSO₄) and N-methylpyrrolidone hydrogen sulfate ([HNMP]HSO₄), are synthesized and employed as extractants to extract thiophene from model gasoline (thiophene dissolved in n-octane). The effect of extraction temperature, extraction time and volume ratio of ILs to model gasoline on desulfurization rates is investigated. Then, the optimal desulfurization conditions are obtained: the ratio of ILs to model gasoline is 1∶1, extraction temperature is 50°C for [HMIm]HSO₄ and 60°C for [HNMP]HSO₄, extraction time is 60 min. Meanwhile, the desulfurization rate of [HNMP]HSO₄ for model gasoline is 62.8%, which is higher than that of [HMIm]HSO₄ (55.5%) under optimal conditions. The reason is discussed on the basis of the interaction energy between thiophene and ILs at the B3LYP/6-311++ G(d,p) level. Furthermore, the total desulfurization rate of [HNMP]HSO₄ and [HMIm]HSO₄ reaches 96.4% and 94.4%, respectively, by multistage extraction. Finally, the used ILs can be reused by vacuum drying, and their desulfurization rates are not significantly decreased after recycling 7 times in single-stage desulfurization.     

Synthesis and applications of highly efficient,reusable, sulfonic acid group functionalized Brönsted acidic ionic liquid catalysts

A variety of sulfonic acid group functionalized Brönsted acidic ionic liquids (BAILs) catalysts were synthesized. Catalytic activities of BAILs were assessed using condensation and esterification reactions. Catalytic activities of BAILs were high when compared with H-ZSM-5, H-BETA, sulfonic acid functionalized SBA-15 catalyst. The Hammett acidity order determined from UV–visible spectroscopy of BAILs is consistent with their activity order observed in acid-catalyzed reactions. Recycling experiments suggests that these novel BAILs can be reused without significant loss in catalytic activity. Novel BAILs offers several attractive features such as low cost, high catalytic activity and recyclability.     

Novel Brønsted acidic ionic liquids catalyzed one-pot reaction of highly green regioselective thiocyanation of N-containing aromatic and heteroaromatic compounds at room temperature

In this method, a novel Brønsted acidic ionic liquid silica-supported pyridinium sulfonic acid thiocyanate {SiO₂@[Pyridine-SO₃H]SCN} and sulfonic acid-functionalized pyridinium chloride {[PSA]Cl} were easily synthesized and characterized. In the first method, {SiO₂@[Pyridine-SO₃H]SCN as a novel and environmentally friendly catalyst with one acidic functional group and one thiocyanation agent group was ef?ciently used for the synthesis of aryl and heteroaryl thiocyanates via the condensation of anilines, indoles, pyrroles, and their derivatives in the presence of H₂O₂ as a green oxidant in EtOH:H₂O (1:1) at room temperature. In the second method, {[PSA]Cl} as a new ionic liquid and environmentally friendly catalyst with one acidic functional group was used for the simple and efficient synthesis of aryl and heteroaryl thiocyanates via the condensation of anilines, indoles, pyrroles, and their derivatives with NH₄SCN in the presence of H₂O₂ as a green oxidant in EtOH:H₂O (1:1) at room temperature. A simple experimental procedure, clean reaction profile, use of an inexpensive catalyst, and recyclability of the catalyst are some of the advantages of the procedure. Also, one of the advantages of the first method is the non-usage of NH₄SCN or KSCN in the reaction.     

Synthesis and application of a novel strong and stable supported ionic liquid catalyst with both Lewis and Brønsted acid sites

Poly(4-vinylpyridine)-supported ionic liquid with both Lewis and Brønsted acid sites was easily prepared from its starting materials and used as a novel and highly efficient heterogeneous catalytic system for the synthesis of biscoumarins by two-component one-pot domino Knoevenagel-type condensation/Michael reaction between various aliphatic and aromatic aldehydes with 4-hydroxycoumarin. The Lewis and Brønsted acidic sites loading in [P₄VPy-BuSO₃H]Cl-X(AlCl₃) were found to be 2.15 and 0.9 mmol per gram of catalyst, respectively. The effect of the simultaneous presence of Lewis and Brønsted acid sites was evaluated. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), elemental analysis, and atomic absorption technique. The catalyst is stable (as a bench top catalyst) and reusable.     

Reactivity of Brönsted acid ionic liquids as dual solvent and catalyst for Fischer esterifications

Several water-stable ionic liquids with different acidity and affinity were synthesized and applied as both solvents and acid catalysts for Fischer esterification of ethanol reacting with four aliphatic carboxylic acids (acetic acid, n-hexanoic acid, lauric acid, and stearic acid). Among the studied ionic liquids, [(n-bu-SO₃H) MIM][HSO₄] (3-butyl-1-(butyl-4-sulfonyl) imidazolium sulfate) and [(n-bu-SO₃H) MIM][p-TSO] (3-butyl-1-(butyl-4-sulfonyl) imidazolium toluenesulfonate) show higher reactivity for the production of ethyl esters. The catalytic activities of these ionic liquids are strongly dependent on the acidity of their anions and cations, as well as their hydrophilicity and affinity with the reactants. Water refluxing through the condenser may be another important reason for obtaining high conversion of esterification, indicating a water-sequester process is still needed in order to obtain a higher yield of ester in the ionic liquid catalyzed esterification system. Kinetics studies show the conversions of the acids increase with reaction temperature and time, and reach equilibrium within about two hours. The apparent activation energies are 39.1±2.0, 49.7±2.5, 51.4±2.5 and 59.3±3.0 kJ·mol⁻¹ for the formation of ethyl acetate, ethyl n-hexanoate, ethyl laurate and ethyl stearate, respectively.     

Oxidative desulfurization of fuels using ionic liquids: A review? ?

Extractive oxidation, wherein aromatic sulfur-containing compounds are extracted and subsequently oxidized to their corresponding sulfones, has proven to be one of the most effective desulfurization methods for producing ultra-low sulfur content fuels. As non-volatile and highly designable solvents, ionic liquids (ILs) have attracted considerable attention for the oxidative desulfurization of fuels. In this review, we systematically discuss the utility of ILs in catalytic and extractive oxidation, including their role as extractant, catalyst, or both. We also discuss the challenges facing the use of ILs in this regard, including their relatively high cost and excessive viscosity, as well as their efficiency and stability as catalyst.     

Kinetics study of the N-formylation of aniline with DMF catalyzed by temperature-controlled Brùnsted ionic liquids

A series of SO₃-functional Br?nsted acidic ionic liquids(SBAILs) were prepared to catalyze the Nformylation of aniline with DMF.The reaction conditions such as ionic liquid type,reaction temperature.catalyst loading and molar ratio of reactants were investigated.To the best of our knowledge,kinetic model for the N-formylation of aniline with DMF using SBAIL was firstly built and simulated.The studies on the reaction order of the reaction were evaluated by initial concentration method,...     

Liquid phase catalytic dehydration of glycerol to acrolein over Brønsted acidic ionic liquid catalysts

Liquid phase dehydration of glycerol to acrolein catalyzed by Brønsted acidic ionic liquids (BAILs) using semi-batch reaction technique was investigated. For the BAILs catalysts, the acrolein yields were in an order of [Bmim]H₂PO₄ > [Bmim]HSO₄ > [BPy]HSO₄ > [PSPy]HSO₄ > [N₂₂₂₄]HSO₄ > [PSPy]H₂PO₄ > [BPy]H₂PO₄ > [N₂₂₂₄]H₂PO₄. When [Bmim]H₂PO₄ and [Bmim]HSO₄ were used as the catalysts at 270 °C with the molar ratio of catalyst to glycerol of 1:100, the acrolein yields were 57.4% and 50.8%, respectively, at complete conversion of glycerol. The BAILs with [Bmim] cation and moderate acidity favored the formation of acrolein in liquid phase glycerol dehydration.     

Transesterification of palm oil to biodiesel using Br(φ)nsted acidic ionic liquid as high-efficient and eco-friendly catalyst

The transesterification of palm oil and methanol catalyzed by Br(φ)nsted acidic ionic liquids was investigated.Four eco-friendly Br(φ)nsted acidic ionic liquids were prepared and their structures were characterized by NMR,FT-IR and TG-DTG.The results demonstrated that [CyN1,1PrSO3H][p-TSA] was more efficient than the other ionic liquids and chosen as catalyst for further research.The influences of various reaction parameters on the conversion of palm oil to biodiesel were performed,and the orthogonal test was investigated to seek the optimum reaction conditions,which were illustrated as follows:methanol to oil mole ratio of 24∶1,catalyst dosage of 3.0 wt％ of oil,reaction temperature of 120 ℃,reaction time of 150 min,and the biodiesel yield achieved 98.4％.In addition,kinetic study was established for the conversion process,with activation energy and preexponential factor of 122.93 kJ·mol-1 and 1.83 × 1015,respectively.Meanwhile,seven-time recycling runs of ionic liquid were completed with ignorable loss of its catalyst activity.The refined biodiesel met the biodiesel standard EN 14214.     

Br?nsted-Lewis酸性离子液体催化合成乙酸正丁酯

合成了[HO_3SC_3-NEt_3]Cl,与ZnCl_2、FeCl_3、AlCl_3、CuCl_2配位制备Br?nsted-Lewis酸性离子液体[HO_3SC_3-NEt_3]XCl_(n+1),通过傅里叶变换红外光谱和核磁氢谱对[HO_3SC_3-NEt_3]Cl结构进行表征。利用Br?nsted-Lewis酸性离子液体催化合成乙酸正丁酯,通过对各种离子液体的腐蚀性和催化性能的综合分析。结果表明,当以[HO_3SC_3-NEt_3]ZnCl_3为催化剂,醇酸摩尔比为1∶1.2,催化剂用量为5%(以正丁醇计量),反应温度为95℃,反应时间为4 h,环己烷为带水剂时,乙酸正丁酯的收率可达到96.94%。     

Br?nsted-Lewis酸性离子液体催化合成乙酸正丁酯

合成了[HO_3SC_3-NEt_3]Cl,与ZnCl_2、FeCl_3、AlCl_3、CuCl_2配位制备Br?nsted-Lewis酸性离子液体[HO_3SC_3-NEt_3]XCl_(n+1),通过傅里叶变换红外光谱和核磁氢谱对[HO_3SC_3-NEt_3]Cl结构进行表征。利用Br?nsted-Lewis酸性离子液体催化合成乙酸正丁酯,通过对各种离子液体的腐蚀性和催化性能的综合分析。结果表明,当以[HO_3SC_3-NEt_3]ZnCl_3为催化剂,醇酸摩尔比为1∶1.2,催化剂用量为5%(以正丁醇计量),反应温度为95℃,反应时间为4 h,环己烷为带水剂时,乙酸正丁酯的收率可达到96.94%。     

Liquid–liquid extraction of hydroxytyrosol,tyrosol, and oleuropein using ionic liquids

ABSTRACT

Hydroxytyrosol (HT), tyrosol (TY), and oleuropein (OL) are valuable compounds that can be obtained from olive oil production waste. This study implemented liquid–liquid extraction to obtain HT, TY, and OL from model solutions using two organic solvents, namely, ethyl acetate and n-butyl acetate, and three ionic liquids (ILs), namely, [P_6,6,6,14][Tf₂N], [P_6,6,6,14][DCA], and [omim][Tf₂N]. [P_6,6,6,14][DCA] showed the best performance, with extraction efficiencies of 92%, 96%, and 83% for HT, TY, and OL, respectively. [omim][Tf₂N] showed the highest selectivity in the extraction of TY. Comparisons of the results of a proposed mathematical model with experimental data yielded errors lower than 0.5%.     

Brønsted acidic ionic liquid as an efficient and recyclable promoter for hydroesterification of olefins catalyzed by a triphenylphosphine–palladium complex

Several Brønsted acidic ionic liquids (BAILs) with different acidic scales were synthesized and employed as acid promoters for the hydroesterification of olefins catalyzed by a triphenylphosphine–palladium complex. The results showed that catalysts with BAIL promoters resulted in moderate to high conversions to the ester product with excellent selectivity, depending on the acidity of BAIL used. The reaction conversion reached a plateau when the catalyst was promoted using BAIL with a Hammett acidity function less than or equal to − 0.11. This catalyst system could be reused several times for the hydroesterification of 1-hexene without a considerable decrease in the catalytic performance.     

Starbon® acids in alkylation and acetylation reactions: Effect of the Brönsted-Lewis acidity

Various Starbon® supported solid acids were prepared and investigated in two test reactions, namely the acetylation of 5-acetyl-methylsalicylate and the alkylation of phenol with cyclohexene. Starbon®-SO₃H materials exhibited in general an optimum balance of Lewis and Bronsted acid sites, making them ideal catalysts for the investigated processes. Starbon acids were comparably active and differently selective compared to similar solid acids utilised in the proposed acid catalysed processes including commercial sulphated zirconia and beta zeolite. Materials were also highly reusable under the different reaction conditions, preserving their activities almost unchanged after 4 reuses.     

Mesoporous silica-functionalized dual Brønsted acidic ionic liquid as an efficient catalyst for thioacetalization of carbonyl compounds in water

A novel silica-functionalized dual Brønsted acidic ionic liquid (ionic liquid with two Brønsted acidic species) has been reported as a highly efficient catalyst for thioacetalization of carbonyl compounds. The reaction was efficiently performed in water as an environmentally benign solvent with good to high yields. Thermal gravimetric analysis showed that the catalyst is stable at least up to 350 °C. Furthermore, the catalyst can be recycled and reused for six runs of reaction without appreciable loss of activity. The structure of the catalyst is modelized to gain more realistic structural insight about the functionalized ionic liquid.     

An expeditious synthesis of homoallylic alcohols using Brønsted acidic supported ionic liquid phase catalyst with pendant ferrocenyl group

A novel Brønsted acidic supported ionic liquid phase catalyst with pendant ferrocenyl group has been synthesized and investigated for the synthesis of homoallylic alcohols from aryl aldehydes and allyltrimethylsilane in THF-H₂O as solvent. The key features of the catalyst include rapid reactions with high yields, excellent catalyst recyclability and total stability under open air conditions.