Generic placeholder image

Current Green Chemistry


ISSN (Print): 2213-3461
ISSN (Online): 2213-347X

Mini-Review Article

Task-specific Ionic Liquids as a Green Catalysts and Solvents for Organic Synthesis

Author(s): Swapnil A. Padvi and Dipak S. Dalal*

Volume 7, Issue 1, 2020

Page: [105 - 119] Pages: 15

DOI: 10.2174/2213346107666200115153051


Task-specific ionic liquids (TSILs) have received increased attention over the past few years as a Green Catalysts and Solvents for a large number of organic transformations. The present review article aims to provide an introduction, types of task-specific ionic liquids, preparation/synthesis, physical properties, characterization, use of TSILs as solvent and catalyst in organic synthesis.

Keywords: Task-specific ionic liquids, green chemistry, organic synthesis, Ionic liquids (ILs), molten salts, typical cations.

Graphical Abstract
Earle, M.J.; Seddon, K.R. Ionic liquids, green solvents for the future. Pure Appl. Chem., 2000, 72, 1391-1398.
Betzemeier, B.; Knochel, P. Perfluorinated solvents-a novel reaction medium in organic chemistry. Modern Solvents in Organic Synthesis Springer, Berlin, Heidelberg, 1999, 206, 60-78.
Mudhoo, A.; Sharma, S.K. Green Chemistry for Environmental Sustainability. 1st ed.; CRC Press, Taylor & Francis Group,. , 2011.
Welton, T. Room-temperature ionic liquids. Solvents for synthesis and catalysis. Chem. Rev., 1999, 99(8), 2071-2084.
[] [PMID: 11849019]
Shen, J.; Wang, H.; Liu, H.; Sun, Y.; Liu, Z. Brønsted acidic ionic liquids as dual catalyst and solvent for environmentally friendly synthesis of chalcone. J. Mol. Catal. Chem., 2008, 280, 24-28.
Aliabadi, R.S.; Mahmoodi, N.O. Green and efficient synthesis of pyranopyrazoles using [Bmim][OH] as an ionic liquid catalyst in water under microwave irradiation and investigation of their antioxidant activity. RSC Advances, 2016, 6, 85877-85884.
Keskin, S.; Kayrak-Talay, D.; Akman, U.; Hortaçsu, O. A review of ionic liquids towards supercritical fluid applications. J. Supercrit. Fluids, 2007, 43, 150-180.
Seddon, K.R. Ionic liquids for clean technology. J. Chem. Technol. Biotechnol., 1997, 68, 351-356.
Plechkova, N.V.; Seddon, K.R. Applications of ionic liquids in the chemical industry. Chem. Soc. Rev., 2008, 37(1), 123-150.
[] [PMID: 18197338]
Wilkes, J.S. Molten salts and ionic liquids-are they not the same thing? ECS Trans., 2007, 3, 3-7.
Rogers, R.D. Ionic liquids--solvents of the future? Science, 2003, 302, 792-793.
Gordon, C.M.; Holbrey, J.D.; Kennedy, A.R.; Seddon, K.R. Ionic liquid crystals: Hexafluorophosphate salts. J. Mater. Chem., 1998, 8, 2627-2636.
Suarez, P.A.Z.; Einloft, S.; Dullius, J.E.L.; de Souza, R.F.J.D. Synthesis and physical-chemical properties of ionic liquids based on 1-n-butyl-3-methylimidazolium cation. J. Chim. Phys., 1998, 95, 1626-1639.
Carmichael, A.J.; Hardacre, C.; Holbrey, J.D.; Nieuwenhuyzen, M.; Seddon, K.R. A method for studying the structure of low-temperature ionic liquids by XAFS. Anal. Chem., 1999, 71, 4572-4574.
Holbrey, J. D.; Seddon, K. R. Tetra fluoroborates ; ionic liquids and ionic liquid crystals. J. Chem. Soc. Dalt. Trans., 1999, (2133), 2139.
Walden, P. Molecular weights and electrical conductivity of several fused salts. Bull. Acad.Imper. Sci., 1914, 8, 405-422.
Chum, H.L.; Koch, V.R.; Miller, L.L.; Osteryoung, R.A. Electrochemical scrutiny of organometallic iron complexes and hexamethyl benzene in a room temperature molten salt. J. Am. Chem. Soc., 1975, 97, 3264-3265.
Wilkes, J.S.; Levisky, J.A.; Wilson, R.A.; Hussey, C.L. Dialkylimidazolium chloroaluminate melts: A new class of room-temperature ionic liquids for electrochemistry, spectroscopy, and synthesis. Inorg. Chem., 1982, 21, 1263-1264.
Wilkes, J.S.; Zaworotko, M.J. Air and water stable 1-ethyl-3-methylimidazolium based ionic liquids. J. Chem. Soc. Chem. Commun., 1992, 13, 965-967.
Davis, H.; Jr, J. Task-specific ionic liquids. Chem. Lett., 2004, 33, 1072-1077.
Martins, M.A.P.P.; Frizzo, C.P.; Moreira, D.N.; Zanatta, N.; Bonacorso, H.G. Ionic liquids in heterocyclic synthesis. Chem. Rev., 2008, 108(6), 2015-2050.
[] [PMID: 18543878]
Vekariya, R.L. A Review of Ionic liquids: applications towards catalytic organic transformations. J. Mol. Liq., 2017, 227, 44-60.
Jessop, P.G.; Ikariya, T.; Noyori, R. Homogeneous catalysis in supercritical fluids. Chem. Rev., 1999, 99(2), 475-494.
[] [PMID: 11848990]
Hussey, C.L. Room temperature haloaluminate ionic liquids. Novel solvents for transition metal solution chemistry. Pure Appl. Chem., 1988, 60, 1763-1772.
Hurley, F.H. WIer, T. P. Electrodeposition of metals from fused quaternary ammonium salts. J. Electrochem. Soc., 1951, 98, 203.
Hurley, F.H. WIer, T. P. The electrodeposition of aluminum from nonaqueous solutions at room temperature. J. Electrochem. Soc., 1951, 98, 207.
Wasserscheid, P.; Keim, W. Ionic liquids–new “solutions” for transition metal catalysis. Angew. Chem. Int. Ed. Engl., 2000, 39(21), 3772-3789.
[<3772::AID-ANIE3772>3.0.CO;2-5] [PMID: 11091453]
Boon, J.A.; Levisky, J.A.; Pflug, J.L.; Wilkes, J.S. Friedel-Crafts reactions in ambient-temperature molten salts. J. Org. Chem., 1986, 51, 480-483.
Fry, S.E.; Pienta, N.J. Effects of molten salts on reactions. nucleophilic aromatic substitution by halide ions in molten dodecyltributylphosphonium salts. J. Am. Chem. Soc., 1985, 107, 6399-6400.
Chauvin, Y.; Gilbert, B.; Guibard, I. Catalytic dimerization of alkenes by nickel complexes in organochloroaluminate molten salts. J. Chem. Soc. Chem. Commun., 1990, 23, 1715.
Surette, J.K.D.; Green, L.; Singer, R.D. 1-Ethyl-3-methylimidazolium halogenoaluminate melts as reaction media for the friedel-crafts acylation of ferrocene. Chem. Commun. (Camb.), 1996, 24, 2753-2754.
Chauvin, Y.; Einloft, S.; Olivier, H. Catalytic dimerization of propene by nickel-phosphine complexes in 1-butyl-3-methylimidazolium chloride/AlEtxCl3-x (x = 0, 1) ionic liquids. Ind. Eng. Chem. Res., 1995, 34, 1149-1155.
Chauvin, Y.; Olivier, H.; Wyrvalski, C.N.; Simon, L.C.; de Souza, R.F. oligomerization of n-butenes catalyzed by nickel complexes dissolved in organochloroaluminate ionic liquids. J. Catal., 1997, 165, 275-278.
Einloft, S.K.; Dietrich, F.F.; De Souza, R.; Dupont, J. Selective two-phase catalytic ethylene dimerization by Ni II complexes/AlEtCl2 dissolved in organoaluminate ionic liquids. Polyhedron, 1996, 15, 3257-3259.
Williams, S.D.; Schoebrechts, J.P.; Selkirk, J.C.; Mamantov, G. A New room temperature molten salt solvent system: organic cation tetrachloroborates. J. Am. Chem. Soc., 1987, 109, 2218-2219.
Monteiro, A.L.; Zinn, F.K.; de Souza, R.F.; Dupont, J. Asymmetric hydrogenation of 2-arylacrylic acids catalyzed by immobilized Ru-BINAP complex in 1-n-butyl-3-methylimidazolium tetrafluoroborate molten salt. Tetrahedron Asymmetry, 1997, 8, 177-179.
Suarez, P.A.Z.; Dullius, J.E.L.; Einloft, S.; de Souza, R.F.; Dupont, J. two-phase catalytic hydrogenation of olefins by Ru(II) and Co(II) complexes dissolved in 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid. Inorg. Chim. Acta, 1997, 255, 207-209.
Pavlinac, J.; Zupan, M.; Laali, K.K.; Stavber, S. Halogenation of organic compounds in ionic liquids. Tetrahedron, 2009, 65, 5625-5662.
Rajagopal, R.; Jarikote, D.V.; Srinivasan, K.V. Ultrasound promoted Suzuki cross-coupling reactions in ionic liquid at ambient conditions. Chem. Commun. (Camb.), 2002, 6(6), 616-617.
[] [PMID: 12120150]
Kamakshi, R.; Reddy, B.S.R. An efficient, eco-friendly, one-pot protocol for the synthesis of 2-oxazolines promoted by ionic liquid/indium chloride. Aust. J. Chem., 2006, 59, 463.
Hou, R.; Wanga, H.M.; Tsai, H-H.; Chen, L.C. Synthesis of 2-phenylthiazoles from α-tosyloxyketones and thiobenzamide in [Bmim][PF6] ionic liquid at ambient temperature. J. Chin. Chem. Soc. (Taipei), 2006, 53, 863-866.
Nadaf, R.N.; Siddiqui, S.A.; Daniel, T.; Lahoti, R.J.; Srinivasan, K.V. Room temperature ionic liquid promoted regioselective synthesis of 2-aryl benzimidazoles, benzoxazoles and benzthiazoles under ambient conditions. J. Mol. Catal. Chem., 2004, 214, 155-160.
Karthikeyan, G.; Perumal, P.T. Ionic liquid promoted simple and efficient synthesis of β-enamino esters and β-enaminones from 1,3-dicarbonyl compounds–one-pot, three-component reaction for the synthesis of substituted pyridines. Can. J. Chem., 2005, 83, 1746-1751.
Peng, J.; Deng, Y. Cycloaddition of carbon dioxide to propylene oxide catalyzed by ionic liquids. New J. Chem., 2001, 25, 639-641.
Hou, R.; Wang, H.M.; Huang, H-Y.; Chen, L.C. Synthesis of imidazo[2,1-a]isoquinolines from α-tosyloxyketones and 1-aminoisoquinoline in ionic liquid solvent. J. Chin. Chem. Soc. (Taipei), 2004, 51, 1417-1420.
Lee, S.G. Functionalized imidazolium salts for task-specific ionic liquids and their applications. Chem. Commun. (Camb.), 2006, 10(10), 1049-1063.
[] [PMID: 16514439]
Huddleston, J.G.; Willauer, H.D.; Swatloski, R.P.; Visser, A.E.; Rogers, R.D. Room temperature ionic liquids as novel media for ‘clean’ liquid–liquid extraction. Chem. Commun. (Camb.), 1998, 16, 1765-1766.
Chiappe, C.; Pieraccini, D. Ionic liquids: solvent properties and organic reactivity. J. Phys. Org. Chem., 2005, 18, 275-297.
Carter, E.B.; Culver, S.L.; Fox, P.A.; Goode, R.D.; Ntai, I.; Tickell, M.D.; Traylor, R.K.; Hoffman, N.W.; Davis, Jr., J.H. Sweet success: Ionic liquids derived from non-nutritive. Chem. Commun. (Camb.), 2004, 6, 630.
[] [PMID: 15010753]
Weingärtner, H. Understanding ionic liquids at the molecular level: facts, problems, and controversies. Angew. Chem. Int. Ed. Engl., 2008, 47(4), 654-670.
[] [PMID: 17994652]
Wilkes, J. Properties of ionic liquid solvents for catalysis. J. Mol. Catal. Chem., 2004, 214, 11-17.
Reichardt, C.; Welton, T. Solvents and Solvent Effects in Organic Chemistry., 2011.
Pollet, P.; Davey, E.A.; Eckert, C.A.; Liotta, C.L. Solvents for sustainable chemical processes. Green Chem., 16, 2014, , 1034-1055.
Pena-Pereira, F.; Kloskowski, A.; Namiesnik, J. Perspectives on the replacement of harmful organic solvents in analytical methodologies: A framework toward the implementation of a generation of eco-friendly alternatives. Green Chem., 2015, 17, 3687-3705.
Byrne, F.P.; Jin, S.; Paggiola, G.; Petchey, T.H.M.; Clark, J.H.; Farmer, T.J.; Hunt, A.J.; Mcelroy, C.R.; Sherwood, J. Tools and techniques for solvent selection : green solvent selection guides. Sustain Chem. Process., 2016, 1-24.
Trohalaki, S.; Pachter, R. Prediction of melting points for ionic liquids. QSAR Comb. Sci., 2005, 485-490.
Chiappe, C.; Malvaldi, M.; Pomelli, C.S. Ionic liquids: Solvation ability and polarity. Pure Appl. Chem., 2009, 81, 767-776.
Reichardt, C. Polarity of ionic liquids determined empirically by means of solvatochromic pyridinium N-phenolate betaine dyes. Green Chem., 2005, 7, 339.
Wakai, C.; Oleinikova, A.; Ott, M.; Weinga, H. How polar are ionic liquids ? Determination of the static dielectric constant of an imidazolium-based ionic liquid by microwave dielectric spectroscopy. 2005, 9-11.
Anderson, J.L.; Ding, J.; Welton, T.; Armstrong, D.W. Characterizing ionic liquids on the basis of multiple solvation interactions. J. Am. Chem. Soc., 2002, 124(47), 14247-14254.
[] [PMID: 12440924]
Ngo, H.L.; LeCompte, K.; Hargens, L.; McEwen, A.B. Thermal properties of imidazolium ionic liquids. thermochim. Acta, 2000, 357-358, 97-102.
Kosmulski, M.; Gustafsson, J.; Rosenholm, J.B. Thermal stability of low temperature ionic liquids revisited. Thermochimica. Acta, 2004, 412, 47-53.
Voroshylova, I.V.; Smaga, S.R.; Lukinova, E.V.; Chaban, V.V.; Kalugin, O.N. Conductivity and association of imidazolium and pyridinium based ionic liquids in methanol. J. Mol. Liq., 2015, 203, 7-15.
Noda, A.; Hayamizu, K.; Watanabe, M. Pulsed-gradient spin-echo 1H and 19F NMR ionic diffusion coefficient, viscosity, and ionic conductivity of non-chloroaluminate room-temperature ionic liquids. J. Phys. Chem. B, 2001, 105, 4603-4610.
Marsh, K.N.; Boxall, J.A.; Lichtenthaler, R. Room temperature ionic liquids and their mixtures - a review. Fluid Phase Equilib., 2004, 219, 93-98.
Huddleston, J.G.; Visser, A.E.; Reichert, W.M.; Willauer, H.D.; Broker, G.A.; Rogers, R.D. Characterization and comparison of hydrophilic and hydrophobic room temperature ionic liquids incorporating the imidazolium cation. Green Chem., 2001, 3, 156-164.
Dzyuba, S.V. Synthesis. properties, and applications of ionic liquids.. Thesis , 2002.
Seddon, K. R.; Stark, A.; Torres, M. J. Viscosity and density of 1- alkyl-3-methylimidazolium ionic liquids. 2002, 34-49.
Fröba, A.P.; Kremer, H.; Leipertz, A. Density, refractive index, interfacial tension, and viscosity of ionic liquids [EMIM][EtSO4], [EMIM][NTf2], [EMIM][N(CN)2], and [OMA][NTf2] in dependence on temperature at atmospheric pressure. J. Phys. Chem. B, 2008, 112(39), 12420-12430.
[] [PMID: 18767789]
MacFarlane, D.R.; Golding, J.; Forsyth, S.; Forsyth, M.; Deacon, G.B. Low viscosity ionic liquids based on organic salts of the dicyanamide anion. Chem. Commun. (Camb.), 2001, 16, 1430-1431.
Ue, M.; Takeda, M.; Toriumi, A.; Kominato, A.; Hagiwara, R.; Ito, Y. Application of low-viscosity ionic liquid to the electrolyte of double-layer capacitors. J. Electrochem. Soc., 2003, 150, A499-A502.
Okoturo, O.O.; Vander Noot, T.J. Temperature dependence of viscosity for room temperature ionic liquids. J. Electroanal. Chem. (Lausanne Switz.), 2004, 568, 167-181.
Olivier-Bourbigou, H.; Magna, L. Ionic liquids: Perspectives for organic and catalytic reactions. J. Mol. Catal. Chem., 2002, 182–183, 419-437.
Docherty, K.M.; Kulpa, C.F., Jr. Toxicity and antimicrobial activity of imidazolium and pyridinium ionic liquids. Green Chem., 2005, 7, 185.
Ranke, J.; Mölter, K.; Stock, F.; Bottin-Weber, U.; Poczobutt, J.; Hoffmann, J.; Ondruschka, B.; Filser, J.; Jastorff, B. Biological effects of imidazolium ionic liquids with varying chain lengths in acute Vibrio fischeri and WST-1 cell viability assays. Ecotoxicol. Environ. Saf., 2004, 58(3), 396-404.
[] [PMID: 15223265]
Stock, F.; Hoffmann, J.; Ranke, J.; Störmann, R.; Ondruschka, B.; Jastorff, B. Effects of ionic liquids on the acetylcholinesterase-a structure-activity relationship consideration. Green Chem., 2004, 6, 286-290.
Swatloski, R.P.; Holbrey, J.D.; Memon, S.B.; Caldwell, G.A.; Caldwell, K.A.; Rogers, R.D. Using Caenorhabditis elegans to probe toxicity of 1-alkyl-3-methylimidazolium chloride based ionic liquids. Chem. Commun. (Camb.), 2004, 58(6), 668-669.
[] [PMID: 15010772]
Fuller, J. The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate: Electrochemical couples and physical properties. J. Electrochem. Soc., 1997, 144, 3881-3886.
Bandini, M.; Eichholzer, A. Catalytic Functionalization of Indoles in a New Dimension, 2009, 48, 9608-9644.
Dupont, J.; Consorti, C.S.; Suarez, P.A.Z.; de Souza, R.F. Preparation of 1-Butyl-3-Methylimidazolium-Based Room Temperature Ionic Liquids. Org. Synth., 2002, 79, 236-240.
Keim, W.; Korth, W.; Wasserscheid, P. WO 016,902 Al, March 30, . 2000.
Kim, Y.J.; Varma, R.S. Microwave-assisted preparation of imidazolium-based tetrachloroindate (III) and their application in the tetrahydropyranylation of alcohols. Tetrahedron Lett., 2005, 46, 1467-1469.
Joseph, T.; Sahoo, S.; Halligudi, S.B. Brönsted acidic ionic liquids: A green, efficient and reusable catalyst system and reaction medium for Fischer esterification. J. Mol. Catal. Chem., 2005, 234, 107-110.
Seddon, K.R.; Stark, A.; Torres, M.J. Influence of chloride, water, and organic solvents on the physical properties of ionic liquids. Pure Appl. Chem., 2000, 72, 2275-2287.
Ranu, B.C.; Banerjee, S. Ionic liquid as catalyst and reaction medium. The dramatic influence of a task-specific ionic liquid, [bmIm]OH, in Michael addition of active methylene compounds to conjugated ketones, carboxylic esters, and nitriles. Org. Lett., 2005, 7(14), 3049-3052.
[] [PMID: 15987202]
Ranu, B.C.; Jana, R. Ionic liquid as catalyst and reaction medium – a simple, efficient and green procedure for knoevenagel condensation of aliphatic and aromatic carbonyl compounds using a task-specific basic ionic liquid. Eur. J. Org. Chem., 2006, 2006, 3767-3770.
Siddiqui, I.R. Rahila; Shamim, S.; Rai, P.; Shireen; Waseem, M. A.; Srivastava, A.; Srivastava, A. Basic ionic liquid promoted domino knoevenagel-thia-michael reaction: an efficient and multicomponent strategy for synthesis of 1,3-thiazines. J. Heterocycl. Chem., 2016, 53, 1284-1291.
Yang, L.; Xu, L.W.; Zhou, W.; Li, L.; Xia, C.G. Highly efficient aza-michael reactions of aromatic amines and n-heterocycles catalyzed by a basic ionic liquid under solvent-free conditions. Tetrahedron Lett., 2006, 47, 7723-7726.
Zang, H.; Wang, M.; Cheng, B.W.; Song, J. Ultrasound-promoted synthesis of oximes catalyzed by a basic ionic liquid [bmIm]OH. Ultrason. Sonochem., 2009, 16(3), 301-303.
[] [PMID: 18977162]
Ranu, B.C.; Jana, R.; Sowmiah, S. An improved procedure for the three-component synthesis of highly substituted pyridines using ionic liquid. J. Org. Chem., 2007, 72(8), 3152-3154.
[] [PMID: 17367198]
Movassagh, B. [bmim]OH-Promoted one-pot, three-component synthesis of β-nitro sulfides in water. Phosphorus Sulfur Silicon Relat. Elem., 2016, 191, 1114-1117.
Patil, Y.P.; Tambade, P.J.; Deshmukh, K.M.; Bhanage, B.M. Synthesis of quinazoline-2,4(1H,3H)-diones from carbon dioxide and 2-aminobenzonitriles using [bmim]OH as a homogeneous recyclable catalyst. Catal. Today, 2009, 148, 355-360.
Tangeti, V.S. Facile ionic liquid-mediated, multi component synthesis of dihydro-1H-furo [2, 3-c] pyrazoles. Asian J. Green Chem., 2019, 3, 306-321.
Singh, V.; Kaur, S.; Sapehiyia, V.; Singh, J.; Kad, G. Microwave accelerated preparation of [bmim][HSO4] ionic liquid: An acid catalyst for improved synthesis of coumarins. Catal. Commun., 2005, 6, 57-60.
Tajik, H.; Niknam, K.; Parsa, F. Using acidic ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate in selective nitration of phenols under mild conditions. J. Iran. Chem. Soc., 2009, 6, 159-164.
Fraga-Dubreuil, J.; Bourahla, K.; Rahmouni, M.; Bazureau, J.P.; Hamelin, J. Catalysed esterifications in room temperature ionic liquids with acidic counteranion as recyclable reaction media. Catal. Commun., 2002, 3, 185-190.
Zeng, Q.; Song, Z.; Qin, H.; Cheng, H.; Chen, L.; Pan, M.; Qi, Z. Ionic liquid [BMIm][HSO4] as dual catalyst-solvent for the esterification of hexanoic acid with n-butanol. Catal. Today, 2020, 339, 113-119.
Niknam, K.; Damya, M. 1-Butyl-3-Methylimidazolium hydrogen sulfate [bmim]HSO4 : An efficient reusable acidic ionic liquid for the synthesis of 1,8-dioxo-octahydroxanthenes. J. Chin. Chem. Soc. (Taipei), 2009, 56, 659-665.
Wasserscheid, P.; Sesing, M.; Korth, W. Hydrogensulfate and tetrakis(hydrogensulfato)borate ionic liquids: synthesis and catalytic application in highly brønsted-acidic systems for Friedel-Crafts alkylation. Green Chem., 2002, 4, 134-138.
Gupta, N.; Kad, G.L.; Singh, J. Acidic ionic liquid [bmim] HSO4: An efficient catalyst for acetalization and thioacetalization of carbonyl compounds and their subsequent deprotection. Catal. Commun., 2007, 8, 1323-1328.
Cai, Y.; Peng, Y.; Song, G. Amino-functionalized ionic liquid as an efficient and recyclable catalyst for knoevenagel reactions in water. Catal. Lett., 2006, 109, 61-64.
Peng, Y.; Song, G. Amino-functionalized ionic liquid as catalytically active solvent for microwave-assisted synthesis of 4H-pyrans. Catal. Commun., 2007, 8, 111-114.
Xing, H.; Wang, T.; Zhou, Z.; Dai, Y. Novel Brønsted-acidic ionic liquids for esterifications. Ind. Eng. Chem. Res., 2005, 44, 4147-4150.
Bicak, N. A new ionic liquid: 2-hydroxy ethylammonium formate. J. Mol. Liq., 2005, 116, 15-18.
Yue, C.; Mao, A.; Wei, Y.; Lü, M. Knoevenagel condensation reaction catalyzed by task-specific ionic liquid under solvent-free conditions. Catal. Commun., 2008, 9, 1571-1574.
Shaterian, H.R.; Arman, M.; Rigi, F. Domino Knoevenagel condensation, Michael addition, and cyclization using ionic liquid, 2-hydroxyethylammonium formate, as a recoverable catalyst. J. Mol. Liq., 2011, 158, 145-150.
Alizadeh, A.; Khodaei, M.M.; Eshghi, A. Ambiphilic dual activation role of a task-specific ionic liquid: 2-hydroxyethylammonium formate as a recyclable promoter and medium for the green synthesis of β-nitrostyrenes. J. Org. Chem., 2010, 75(23), 8295-8298.
[] [PMID: 21047089]
Rajabzadeh, M.; Eshghi, H.; Khalifeh, R.; Bakavoli, M. 2‐ hydroxyethylammonium formate ionic liquid grafted magnetic nanoparticle as a novel heterogeneous catalyst for the synthesis of substituted imidazoles. Appl. Organomet. Chem., , 2018, 32, e4052
Tzani, A.; Douka, A.; Papadopoulos, A.; Pavlatou, E.A.; Voutsas, E.; Detsi, A. Synthesis of biscoumarins using recyclable and biodegradable task-specific ionic liquids. ACS Sustain. Chem.& Eng., 2013, 1, 1180-1185.
Dong, F.; Jian, C.; Zhenghao, F.; Kai, G.; Zuliang, L. Synthesis of chalcones via Claisen–Schmidt condensation reaction catalyzed by acyclic acidic ionic liquids. Catal. Commun., 2008, 9, 1924-1927.
Liu, X.; Lu, M.; Gu, G.; Lu, T. Aza-Michael reactions in water using functionalized ionic liquids as the recyclable catalysts. J. Indian Chem. Soc., 2011, 8, 775-781.
Dong, F.; Jun, L.; Xin-Li, Z.; Zu-Liang, L. Mannich reaction in water using acidic ionic liquid as recoverable and reusable catalyst. Catal. Lett., 2007, 116, 76-80.
Fang, D.; Zhang, H.B.; Liu, Z.L. Synthesis of 4H‐benzopyrans catalyzed by acyclic acidic ionic liquids in aqueous media. J. Heterocycl. Chem., 2010, 47, 63-67.
Ying, A.G. Preparation of DBU derived task-specific ionic liquids and the study of their application in the Michael additions and Knoevenagel condensations. . Thesis, 2010.
Ying, A.G.; Liu, L.; Wu, G.F.; Chen, G.; Chen, X.Z.; Ye, W.D. Aza-Michael addition of aliphatic or aromatic amines to α, β-unsaturated compounds catalyzed by a DBU-derived ionic liquid under solvent-free conditions. Tetrahedron Lett., 2009, 50, 1653-1657.
Chen, X.; Zhou, S.; Qian, C. Hydrogen transfer reduction of nitriles in DBU based ionic liquids. ARKIVOC, 2012, 8, 128-136.
Liu, F.; Guo, J.; Zhao, P.; Gu, Y.; Gao, J.; Liu, M. Facile synthesis of DBU-based protic ionic liquid for efficient alcoholysis of waste poly (lactic acid) to lactate esters. Polym. Degrad. Stabil., 2019, 167, 124-129.
Ying, A.G.; Liu, L.; Wu, G.F.; Chen, X.Z.; Ye, W.D.; Chen, J.H.; Zhang, K.Y. Knoevenagel condensation catalyzed by DBU brønsted ionic liquid without solvent. Chem. Res. Chin. Univ., 2009, 25, 876-881.
Maleki, B.; Akbarzadeh, E.; Babaee, S. New basic ionic liquid from ethan-1, 2-diyl bis (hydrogen sulfate) and DBU (1, 8-diazobicyclo [5.4. 0] undec-7-ene) as an efficient catalyst for one-pot synthesis of xanthene derivatives. Dyes and Pigm., 2015, 123, 222-234.
Yu, B.; Zhang, H.; Zhao, Y.; Chen, S.; Xu, J.; Hao, L.; Liu, Z. DBU-based ionic-liquid-catalyzed carbonylation of o-phenylenediamines with CO2 to 2-benzimidazolones under solvent-free conditions. ACS Catal., 2013, 3, 2076-2082.
Xu, D.Z.; Shi, S.; Wang, Y. Polystyrene-immobilized DABCO as a highly efficient and recyclable organocatalyst for the Knoevenagel condensation reaction. RSC Advances, 2013, 3, 23075-23079.
Yu, Y.Q.; Xu, D.Z. A quaternary ammonium salt [H-dabco][AcO]: as a recyclable and highly efficient catalyst for the one-pot synthesis of β-phosphonomalonates. RSC Advances, 2015, 5, 28857-28863.
Jamasbi, N.; Irankhah-Khanghah, M.; Shirini, F.; Tajik, H.; Langarudi, M.S.N. DABCO-based ionic liquids: Introduction of two metal-free catalysts for one-pot synthesis of 1, 2, 4-triazolo [4, 3-a] pyrimidines and pyrido [2,3-d] pyrimidines. New J. Chem., 2018, 42, 9016-9027.
Yang, C.; Liu, P.Z.; Xu, D.Z. A green and efficient one‐pot pseudo‐five‐component reaction for synthesis of bis (pyrazol‐5‐ol) derivatives via tandem cyclocondensation‐Knoevenagel-Michael reaction. ChemistrySelect, 2017, 2, 1232-1236.
Shirini, F.; Langarudi, M.S.N.; Daneshvar, N.; Mashhadinezhad, M.; Nabinia, N. Preparation of a new DABCO-based ionic liquid and investigation on its application in the synthesis of benzimidazoquinazolinone and pyrimido [4,5-b]-quinoline derivatives. J. Mol. Liq., 2017, 243, 302-312.
Liu, P.; Hao, J.W.; Mo, L.P.; Zhang, Z.H. Recent advances in the application of deep eutectic solvents as sustainable media as well as catalysts in organic reactions. RSC Advances, 2015, 5, 48675-48704.
Zhang, Q.; De Oliveira Vigier, K.; Royer, S.; Jérôme, F. Deep eutectic solvents: syntheses, properties and applications. Chem. Soc. Rev., 2012, 41(21), 7108-7146.
[] [PMID: 22806597]
Pätzold, M.; Siebenhaller, S.; Kara, S.; Liese, A.; Syldatk, C.; Holtmann, D. Deep eutectic solvents as efficient solvents in biocatalysis. Trends Biotechnol., 2019, 37(9), 943-959.
[] [PMID: 31000203]
Vanda, H.; Dai, Y.; Wilson, E.G.; Verpoorte, R.; Choi, Y.H. Green solvents from ionic liquids and deep eutectic solvents to natural deep eutectic solvents. C. R. Chim., 2018, 21, 628-638.
Hu, H.; Qiu, F.; Ying, A.; Yang, J.; Meng, H. An environmentally benign protocol for aqueous synthesis of tetrahydrobenzo[b]pyrans catalyzed by cost-effective ionic liquid. Int. J. Mol. Sci., 2014, 15(4), 6897-6909.
[] [PMID: 24758931]
Disale, S.T.; Kale, S.R.; Kahandal, S.S.; Srinivasan, T.G.; Jayaram, R.V. Choline chloride· 2ZnCl2 ionic liquid: An efficient and reusable catalyst for the solvent free Kabachnik–Fields reaction. Tet. Lett, 2012, 53, 2277-2279.
Wang, P.; Ma, F.P.; Zhang, Z.H. L-(+)-Tartaric acid and choline chloride based deep eutectic solvent: An efficient and reusable medium for synthesis of N-substituted pyrroles via Clauson-Kaas reaction. J. Mol. Liq., 2014, 198, 259-262.

© 2023 Bentham Science Publishers | Privacy Policy