Document Type: Short Review Article


Department of Chemistry, Faculty of Sciences, University of Hormozgan, Bandar Abbas 71961, Iran



Nowadays chemists seem more interested in using less toxic substances, which may result in reducing the environmental hazards.Ionic liquids (ILs) are less toxic than many common compounds. These compounds have emerged as environmentally-friendly alternative to the volatile organic solvents and catalysts. In this research study, the properties and applications of some ILs including, chiral ILs, high energetic ILs, task-specific ILs, supported ILs, polymeric ILs, acid ILs, basic ILs, and organometallic ILs were investigated. In addition, the advantages of the ILs in organic chemistry as solvents and catalysts were discussed.

Graphical Abstract


[1] Ferraz, R., Branco, L. C., Prudencio, C., Noronha, J. P., & Petrovski, Ž. (2011). Ionic liquids as active pharmaceutical ingredients. Chem. Med. Chem., 6(6), 975-985.

[2] Zhao, H., Malhotra, S. V. (2002). Applications of ionic liquids in organic synthesis, Aldrichimica Acta, 35(3), 75-83.

[3] Earle, M. J., & Seddon, K. R. (2000). Special topic issue on green chemistry. Pure Appl. Chem, 72(7), 1391-1398.

[4] Cooper, E. R., Andrews, C. D., Wheatley, P. S., Webb, P. B., Wormald, P., & Morris, R. E. (2004). Ionic liquids and eutectic mixtures as solvent and template in synthesis of zeolite analogues. Nature, 430(7003), 1012-1016.

[5] Yoshizawa, M., Narita, A., & Ohno, H. (2004). Design of ionic liquids for electrochemical applications. Australian journal of chemistry, 57(2), 139-144.

[6] Keskin, S., Kayrak-Talay, D., Akman, U., & Hortaçsu, Ö. (2007). A review of ionic liquids towards supercritical fluid applications. The Journal of Supercritical Fluids, 43(1), 150-180.

[7] Palacio, M., & Bhushan, B. (2010). A review of ionic liquids for green molecular lubrication in nanotechnology. Tribology Letters, 40(2), 247-268.

[8] Gabriel, S., & Weiner, J. (1888). Ueber einige abkömmlinge des propylamins. Berichte der deutschen chemischen Gesellschaft, 21(2), 2669-2679.

[9] Singh, A., & Chopra, H. K. (2018). Synthesis, characterization and applications of some novel DMAP-based chiral ionic liquids. Journal of Molecular Liquids, 266, 106-111.

[10] Wang, Z., Jin, Y., Zhang, W., Wang, B., Liu, T., Zhang, J., & Zhang, Q. (2019). Synthesis and hypergolic properties of flammable ionic liquids based on the cyano (1 H-1, 2, 3-triazole-1-yl) dihydroborate anion. Dalton Transactions, 48(18), 6198-6204.

[11] Korade, S. N., Patil, J. D., & Pore, D. M. (2016). Novel task-specific ionic liquid for room temperature synthesis of spiro-1, 2, 4-triazolidine-3-thiones. Monatshefte für Chemie-Chemical Monthly, 147(12), 2143-2149.

[12] Tian, M., Bi, W., & Row, K. H. (2013). Multi‐phase extraction of glycoraphanin from broccoli using aminium ionic liquid‐based silica. Phytochemical Analysis, 24(1), 81-86.

[13] Young, J. A., Zhang, C., Devasurendra, A. M., Tillekeratne, L. V., Anderson, J. L., & Kirchhoff, J. R. (2016). Conductive polymeric ionic liquids for electroanalysis and solid-phase microextraction. Analytica chimica acta, 910, 45-52.

[14] Amarasekara, A. S. (2016). Acidic ionic liquids. Chemical reviews, 116(10), 6133-6183.

[15] Boruah, K., & Borah, R. (2019). Design of Water Stable 1, 3‐Dialkyl‐2‐Methyl Imidazolium Basic Ionic Liquids as Reusable Homogeneous Catalysts for Aza‐Michael Reaction in Neat Condition. ChemistrySelect, 4(12), 3479-3485.

[16] Inagaki, T., Mochida, T., Takahashi, M., Kanadani, C., Saito, T., & Kuwahara, D. (2012). Ionic liquids of cationic sandwich complexes. Chemistry–A European Journal, 18(22), 6795-6804.

[17] Hurley, F. H., & Wier Jr, T. P. (1951). Electrodeposition of metals from fused quaternary ammonium salts. Journal of The Electrochemical Society, 98(5), 203.

[18] Wasserscheid, P., & Welton, T. (Eds.). (2008). Ionic liquids in synthesis. John Wiley & Sons.

[19] Wilkes, J. S., & Zaworotko, M. J. (1992). Air and water stable 1-ethyl-3-methylimidazolium based ionic liquids. Journal of the Chemical Society, Chemical Communications, (13), 965-967.

[20] Olivier-Bourbigou, H., Magna, L., & Morvan, D. (2010). Ionic liquids and catalysis: Recent progress from knowledge to applications. Applied Catalysis A: General, 373(1-2), 1-56.

[21] Smiglak, M., Holbrey, J. D., Griffin, S. T., Reichert, W. M., Swatloski, R. P., Katritzky, A. R., ... & Rogers, R. D. (2007). Ionic liquids via reaction of the zwitterionic 1, 3-dimethylimidazolium-2-carboxylate with protic acids. Overcoming synthetic limitations and establishing new halide free protocols for the formation of ILs. Green Chemistry, 9(1), 90-98.

[22] Holbrey, J. D., Reichert, W. M., Swatloski, R. P., Broker, G. A., Pitner, W. R., Seddon, K. R., & Rogers, R. D. (2002). Efficient, halide free synthesis of new, low cost ionic liquids: 1, 3-dialkylimidazolium salts containing methyl-and ethyl-sulfate anions. Green Chemistry, 4(5), 407-413.

[23] a) Horikoshi, S., Hamamura, T., Kajitani, M., Yoshizawa-Fujita, M., & Serpone, N. (2008). Green chemistry with a novel 5.8-GHz microwave apparatus. Prompt one-pot solvent-free synthesis of a major ionic liquid: the 1-butyl-3-methylimidazolium tetrafluoroborate system. Organic Process Research & Development, 12(6), 1089-1093. b) Alni, A., Cahya, A. Y., & Wahyuningrum, D. (2019). Synthesis of Imidazolium Based Ionic Liquids and Its Application as Medium in Cyclization Reaction of Diketone. In Key Engineering Materials (Vol. 811, pp. 86-91). Trans Tech Publications Ltd.

[24] Ohno, H., & Fukumoto, K. (2007). Amino acid ionic liquids. Accounts of chemical research, 40(11), 1122-1129.

[25] Fukumoto, K., & Ohno, H. (2006). Design and synthesis of hydrophobic and chiral anions from amino acids as precursor for functional ionic liquids. Chemical communications, (29), 3081-3083.

[26] Allen, C. R., Richard, P. L., Ward, A. J., van de Water, L. G., Masters, A. F., & Maschmeyer, T. (2006). Facile synthesis of ionic liquids possessing chiral carboxylates. Tetrahedron letters, 47(41), 7367-7370.

[27] Zhang, S., Huang, Y., Jing, H., Yao, W., & Yan, P. (2009). Chiral ionic liquids improved the asymmetric cycloaddition of CO 2 to epoxides. Green Chemistry, 11(7), 935-938.

[28] Ding, J., & Armstrong, D. W. (2005). Chiral ionic liquids: synthesis and applications. Chirality, 17(5), 281-292.

[29] Siyutkin, D. E., Kucherenko, A. S., & Zlotin, S. G. (2010). A new (S)-prolinamide modified by an ionic liquid moiety—a high performance recoverable catalyst for asymmetric aldol reactions in aqueous media. Tetrahedron, 66(2), 513-518.

[30] Zhang, Q., & Shreeve, J. N. M. (2014). Energetic ionic liquids as explosives and propellant fuels: a new journey of ionic liquid chemistry. Chemical reviews, 114(20), 10527-10574.

[31] a) Klapötke, T. M., & Stierstorfer, J. (2009). Azidoformamidinium and 5-aminotetrazolium dinitramide—two highly energetic isomers with a balanced oxygen content. Dalton Transactions, (4), 643-653. b) Jolodar, O. G., Ghauri, K., Seddighi, M., Shirini, F., & Bayat, Y. (2019). Preparation and characterization of ethane-1, 2-diaminium trinitromethanide as a novel energetic ionic liquid. Journal of Molecular Structure, 1186, 448-457.

[32] Smiglak, M., Hines, C. C., Reichert, W. M., Vincek, A. S., Katritzky, A. R., Thrasher, J. S., ... & Rogers, R. D. (2012). Synthesis, limitations, and thermal properties of energetically-substituted, protonated imidazolium picrate and nitrate salts and further comparison with their methylated analogs. New Journal of Chemistry, 36(3), 702-722.

[33] Lancaster, N. L., & Llopis-Mestre, V. (2003). Aromatic nitrations in ionic liquids: the importance of cation choice. Chemical communications, (22), 2812-2813.

[34] Earle, M. J., Katdare, S. P., & Seddon, K. R. (2004). Paradigm confirmed: the first use of ionic liquids to dramatically influence the outcome of chemical reactions. Organic letters, 6(5), 707-710.

[35] Smith, K., Liu, S., & El-Hiti, G. A. (2005). Regioselective mononitration of simple aromatic compounds under mild conditions in ionic liquids. Industrial & engineering chemistry research, 44(23), 8611-8615.

[36] Laali, K. K., & Gettwert, V. J. (2001). Electrophilic nitration of aromatics in ionic liquid solvents. The Journal of organic chemistry, 66(1), 35-40.

[37] Qiao, K., & Yokoyama, C. (2004). Nitration of aromatic compounds with nitric acid catalyzed by ionic liquids. Chemistry letters, 33(7), 808-809.

[38] Hale, G. C. (1925). The Nitration of Hexamethylenetetramine1, 2. Journal of the American Chemical Society, 47(11), 2754-2763.

[39] Francis, G. W., A. Forster, and E. Roberts. 1950. Cyclotrimethylenetrinitramine. U.S. patent no. 2,525,252.

[40] Bachmann, W. E., & Sheehan, J. C. (1949). A new method of preparing the high explosive RDX. Journal of the American Chemical Society, 71(5), 1842-1845.

[41] Cheng, G., Li, X., Qi, X., & Lu, C. (2010). Synthesis of RDX Catalyzed by Br⊘nsted Acidic Ionic Liquids. Journal of Energetic Materials, 28(1), 35-44.

[42] Zhi, H. Z., Luo, J., Feng, G. A., & Lv, C. X. (2009). An efficient method to synthesize HMX by nitrolysis of DPT with N2O5 and a novel ionic liquid. Chinese Chemical Letters, 20(4), 379-382.

[43] Bates, E. D., Mayton, R. D., Ntai, I., & Davis, J. H. (2002). CO2 capture by a task-specific ionic liquid. Journal of the American Chemical Society, 124(6), 926-927.

[44] Cole, A. C., Jensen, J. L., Ntai, I., Tran, K. L. T., Weaver, K. J., Forbes, D. C., & Davis, J. H. (2002). Novel Brønsted acidic ionic liquids and their use as dual solvent− catalysts. Journal of the American Chemical Society, 124(21), 5962-5963.

[45] Korade, S. N., Patil, J. D., & Pore, D. M. (2016). Novel task-specific ionic liquid for room temperature synthesis of spiro-1, 2, 4-triazolidine-3-thiones. Monatshefte für Chemie-Chemical Monthly, 147(12), 2143-2149.

[46] Tong, X., Ma, Y., & Li, Y. (2010). An efficient catalytic dehydration of fructose and sucrose to 5-hydroxymethylfurfural with protic ionic liquids. Carbohydrate research, 345(12), 1698-1701.

[47] Fei, Z., Geldbach, T. J., Zhao, D., & Dyson, P. J. (2006). From dysfunction to bis‐function: on the design and applications of functionalised ionic liquids. ChemistryA European Journal, 12(8), 2122-2130.

[48] Yue, C., Fang, D., Liu, L., & Yi, T. F. (2011). Synthesis and application of task-specific ionic liquids used as catalysts and/or solvents in organic unit reactions. Journal of Molecular Liquids, 163(3), 99-121.

[49] Feder-Kubis, J., Kubicki, M., & Pernak, J. (2010). 3-Alkoxymethyl-1-(1R, 2S, 5R)-(−)-menthoxymethylimidazolium salts-based chiral ionic liquids. Tetrahedron: Asymmetry, 21(21-22), 2709-2718.

[50] Soleimani, O., & Hosseinian, A. (2018). Direct synthesis of xanthenes from benzyl alcohols using choline peroxydisulfate ionic liquid as a reagent under otherwise solvent-free conditions. Journal of Chemical Research, 42(6), 337-340.

[51] Van Doorslaer, C., Wahlen, J., Mertens, P., Binnemans, K., & De Vos, D. (2010). Immobilization of molecular catalysts in supported ionic liquid phases. Dalton Transactions, 39(36), 8377-8390.

[52] Zhao, D., Liao, Y., & Zhang, Z. (2007). Toxicity of ionic liquids. Clean–soil, air, water, 35(1), 42-48.

[53] Jadhav, J., Gaikwad, V., Kurane, R., Salunkhe, R., & Rashinkar, G. (2013). Intramolecular O-arylation route to 2-substituted benzoxazoles mediated by ferrocene tethered polymer supported ionic liquid phase catalyst. Tetrahedron, 69(14), 2920-2926.

[54] Choi, H. J., Selvaraj, M., & Park, D. W. (2013). Catalytic performance of immobilized ionic liquid onto PEG for the cycloaddition of carbon dioxide to allyl glycidyl ether. Chemical Engineering Science, 100, 242-248.

[55] Kim, D. W., & Chi, D. Y. (2004). Polymer‐Supported Ionic Liquids: Imidazolium Salts as Catalysts for Nucleophilic Substitution Reactions Including Fluorinations. Angewandte Chemie International Edition, 43(4), 483-485.

[56] Sans, V., Karbass, N., Burguete, M. I., Compañ, V., García‐Verdugo, E., Luis, S. V., & Pawlak, M. (2011). Polymer‐Supported Ionic‐Liquid‐Like Phases (SILLPs): Transferring Ionic Liquid Properties to Polymeric Matrices. ChemistryA European Journal, 17(6), 1894-1906.

[57] Riisager, A., Fehrmann, R., Haumann, M., & Wasserscheid, P. (2006). Supported ionic liquid phase (SILP) catalysis: An innovative concept for homogeneous catalysis in continuous fixed‐bed reactors. European Journal of Inorganic Chemistry, 2006(4), 695-706.

[58] Mehnert, C. P. (2005). Supported ionic liquid catalysis. Chemistry–A European Journal, 11(1), 50-56.

[59] Corma, A. (1997). From microporous to mesoporous molecular sieve materials and their use in catalysis. Chemical reviews, 97(6), 2373-2420.

[60] Banerjee, A. K., Mimo, M. L., & Vegas, W. V. (2001). Silica gel in organic synthesis. Russian Chemical Reviews, 70(11), 971-990.

[61] Armistead, C. G., Tyler, A. J., Hambleton, F. H., Mitchell, S. A., & Hockey, J. A. (1969). Surface hydroxylation of silica. The Journal of Physical Chemistry, 73(11), 3947-3953.

[62] Mehnert, C. P., Cook, R. A., Dispenziere, N. C., & Afeworki, M. (2002). Supported ionic liquid catalysis− A new concept for homogeneous hydroformylation catalysis. Journal of the American Chemical Society, 124(44), 12932-12933.

[63] Mehnert, C. P. (2005). Supported ionic liquid catalysis. Chemistry–A European Journal, 11(1), 50-56.

[64] Hajipour, A. R., & Rafiee, F. (2015). Recent progress in ionic liquids and their applications in organic synthesis. Organic Preparations and Procedures International, 47(4), 249-308.

[65] Dimitrov‐Raytchev, P., Beghdadi, S., Serghei, A., & Drockenmuller, E. (2013). Main‐chain 1, 2, 3‐triazolium‐based poly (ionic liquid) s issued from AB+ AB click chemistry polyaddition. Journal of Polymer Science Part A: Polymer Chemistry, 51(1), 34-38.

[66] Chen, X., Zhao, J., Zhang, J., Qiu, L., Xu, D., Zhang, H., ... & Yan, F. (2012). Bis-imidazolium based poly (ionic liquid) electrolytes for quasi-solid-state dye-sensitized solar cells. Journal of Materials Chemistry, 22(34), 18018-18024.

[67] Marcilla, R., Alcaide, F., Sardon, H., Pomposo, J. A., Pozo-Gonzalo, C., & Mecerreyes, D. (2006). Tailor-made polymer electrolytes based upon ionic liquids and their application in all-plastic electrochromic devices. Electrochemistry communications, 8(3), 482-488.

[68] Song, H., Jin, F., Kang, M., & Chen, J. (2019). Novel polymeric acidic ionic liquids as green catalysts for the preparation of polyoxymethylene dimethyl ethers from the acetalation of methylal with trioxane. RSC Advances, 9(69), 40662-40669.

[69] Liu, S., Xie, C., Yu, S., & Liu, F. (2008). Dimerization of rosin using Brønsted–Lewis acidic ionic liquid as catalyst. Catalysis Communications, 9(10), 2030-2034.

[70] Shiwei, L. I. U., Congxia, X. I. E., Shitao, Y. U., Mo, X., & Fusheng, L. (2009). A Brønsted-Lewis acidic ionic liquid: its synthesis and use as the catalyst in rosin dimerization. Chinese Journal of Catalysis, 30(5), 401-406.

[71] Zhang, H., Xu, F., Zhou, X., Zhang, G., & Wang, C. (2007). A Brønsted acidic ionic liquid as an efficient and reusable catalyst system for esterification. Green Chemistry, 9(11), 1208-1211.

[72] Forbes, D. C., & Weaver, K. J. (2004). A Novel Task-Specific Ionic Liquid for Bechman Rearrangement. J. Mol. Catal. A: Chem, 214, 129-132.

[73] Safari, J., & Zarnegar, Z. (2014). Brønsted acidic ionic liquid based magnetic nanoparticles: a new promoter for the Biginelli synthesis of 3, 4-dihydropyrimidin-2 (1 H)-ones/thiones. New Journal of Chemistry, 38(1), 358-365.

[74] Heravi, M. M., Saeedi, M., Karimi, N., Zakeri, M., Beheshtiha, Y. S., & Davoodnia, A. (2010). Brønsted acid ionic liquid [(CH2) 4SO3HMIM][HSO4] as novel catalyst for one-pot synthesis of Hantzsch polyhydroquinoline derivatives. Synthetic Communications®, 40(4), 523-529.

[75] Behjatmanesh-Ardakani, R., Safaeian, N., Oftadeh, M., & Fallah-Mehrjardi, M. (2020). Knoevenagel condensation versus Michael addition reaction in ionic-liquid-catalyzed synthesis of hexahydroquinoline: a SMD–DFT study. Theoretical Chemistry Accounts, 139(3), 1-8.

[76] Ressmann, A. K., Schneider, M., Gaertner, P., Weil, M., & Bica, K. (2017). Design and synthesis of basic ionic liquids for the esterification of triterpenic acids. Monatshefte für Chemie-Chemical Monthly, 148(1), 139-148.

[77] Xu, J. M., Liu, B. K., Wu, W. B., Qian, C., Wu, Q., & Lin, X. F. (2006). Basic ionic liquid as catalysis and reaction medium: a novel and green protocol for the Markovnikov addition of N-heterocycles to vinyl esters, using a task-specific ionic liquid,[bmIm] OH. The Journal of organic chemistry, 71(10), 3991-3993.

[78] Yang, Z. Z., He, L. N., Miao, C. X., & Chanfreau, S. (2010). Lewis basic ionic liquids‐catalyzed conversion of carbon dioxide to cyclic carbonates. Advanced Synthesis & Catalysis, 352(13), 2233-2240.

[79] Ranu, B. C., & Jana, R. (2006). 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. European journal of organic chemistry, 2006(16), 3767-3770.

[80] Shaterian, H. R., & Mohammadnia, M. (2012). Mild basic ionic liquids catalyzed new four-component synthesis of 1H-pyrazolo [1, 2-b] phthalazine-5, 10-diones. Journal of Molecular Liquids, 173, 55-61.

[81] Winkel, A., & Wilhelm, R. (2010). New chiral ionic liquids based on enantiopure sulfate and sulfonate anions for chiral recognition. European Journal of Organic Chemistry, 2010(30), 5817-5824.

[82] Huang, J. F., Luo, H., Liang, C., Jiang, D. E., & Dai, S. (2008). Advanced liquid membranes based on novel ionic liquids for selective separation of olefin/paraffin via olefin-facilitated transport. Industrial & engineering chemistry research, 47(3), 881-888.

[83] Lecocq, V., Graille, A., Santini, C. C., Baudouin, A., Chauvin, Y., Basset, J. M., ... & Fenet, B. (2005). Synthesis and characterization of ionic liquids based upon 1-butyl-2, 3-dimethylimidazolium chloride/ZnCl 2. New journal of chemistry, 29(5), 700-706.

[84] Kumar, A., & Pawar, S. S. (2005). Catalyzing Henry reactions in chloroaluminate ionic liquids. Journal of Molecular Catalysis A: Chemical, 235(1-2), 244-248.

[85] a) Stefaniak, W., Janus, E., & Milchert, E. (2011). Diels–Alder Reaction of Cyclopentadiene and Alkyl Acrylates in the Presence of Pyrrolidinium Ionic Liquids with Various Anions. Catalysis letters, 141(5), 742-747. b) Yadav, G. D., Chaudhary, P., Aalam, M. J., Meena, D. R., & Singh, S. (2020). Chiral Imidazolidin‐4‐one with catalytic amount of Dicationic ionic liquid act as a recoverable and reusable Organocatalyst for asymmetric Diels‐Alder reaction. Chirality, 32(1), 64-72.

[86] Rebeiro, G. L., & Khadilkar, B. M. (2001). Chloroaluminate ionic liquid for Fischer indole synthesis. Synthesis, 2001(03), 0370-0372.

[87] Neuhaus, W. C., Bakanas, I. J., Lizza, J. R., Boon, C. T., & Moura-Letts, G. (2016). Novel biodegradable protonic ionic liquid for the Fischer indole synthesis reaction. Green Chemistry Letters and Reviews, 9(1), 39-43.

[88] Fang, D., Zhou, X. L., Ye, Z. W., & Liu, Z. L. (2006). Brønsted acidic ionic liquids and their use as dual solvent− catalysts for Fischer esterifications. Industrial & engineering chemistry research, 45(24), 7982-7984.

[89] Reddy, P. S., Kanjilal, S., Sunitha, S., & Prasad, R. B. (2007). Reductive amination of carbonyl compounds using NaBH4 in a Brønsted acidic ionic liquid. Tetrahedron letters, 48(50), 8807-8810.

[90] Strecker, A. (1850). Ueber die künstliche Bildung der Milchsäure und einen neuen, dem Glycocoll homologen Körper. Justus Liebigs Annalen der Chemie, 75(1), 27-45.

[91] Al Otaibi, A., & McCluskey, A. (2013). Multicomponent reactions in ionic liquids. Ionic Liquids: New Aspects for the Future, 457.

[92] Zhao, G., Jiang, T., Gao, H., Han, B., Huang, J., & Sun, D. (2004). Mannich reaction using acidic ionic liquids as catalysts and solvents. Green Chemistry, 6(2), 75-77.

[93] Hantzsch, A. (1881). Condensationsprodukte aus Aldehydammoniak und ketonartigen Verbindungen. Berichte der deutschen chemischen Gesellschaft, 14(2), 1637-1638.

[94] Avalani, J. R., Patel, D. S., & Raval, D. K. (2012). 1-Methylimidazolium trifluoroacetate [Hmim] Tfa: Mild and efficient Brønsted acidic ionic liquid for Hantzsch reaction under microwave irradiation. Journal of Chemical Sciences, 124(5), 1091-1096.

[95] Tan, J., Liu, X., Yao, N., Hu, Y. L., & Li, X. H. (2019). Novel and Effective Strategy of Multifunctional Titanium Incorporated Mesoporous Material Supported Ionic Liquid Mediated Reusable Hantzsch Reaction. ChemistrySelect, 4(8), 2475-2479.

[96] Larsen, S. D., & Grieco, P. A. (1985). Aza Diels-Alder reactions in aqueous solution: cyclocondensation of dienes with simple iminium salts generated under Mannich conditions. Journal of the American Chemical Society, 107(6), 1768-1769.

[97] Grieco, P. A., & Bahsas, A. (1988). Role reversal in the cyclocondensation of cyclopentadiene with heterodienophiles derived from aryl amines and aldehydes: Synthesis of novel tetrahydroquinolines. Tetrahedron letters, 29(46), 5855-5858.

[98] Dubois, P., Marchand, G., Gmouh, S., & Vaultier, M. (2007). Reaction Rates as a Function of Scale within Ionic Liquids: Microscale in Droplet Microreactors versus Macroscale Reactions in the Case of the Grieco Three‐Component Condensation Reaction. ChemistryA European Journal, 13(19), 5642-5648.

[99] Biginelli, P. (1891). Ueber aldehyduramide des acetessigäthers. Berichte der deutschen chemischen Gesellschaft, 24(1), 1317-1319.

[100] Peng, J., & Deng, Y. (2001). Ionic liquids catalyzed Biginelli reaction under solvent-free conditions. Tetrahedron Letters, 42(34), 5917-5919.

[101] Yao, N., Lu, M., Liu, X. B., Tan, J., & Hu, Y. L. (2018). Copper-doped mesoporous silica supported dual acidic ionic liquid as an efficient and cooperative reusability catalyst for Biginelli reaction. Journal of Molecular Liquids, 262, 328-335.