Abstract
This chapter is dedicated to hydrogenation procedures of (poly)-alkenes or unsaturated ketones in various biobased and not-biobased ionic liquids. The first part of this chapter defines the concept of biobased ionic liquids and their preparation. In the second part, hydrogenation processes performed in non-biobased ionic liquids are described. Finally, in the last part, the two themes are mixed and recent examples of hydrogenation procedures of alkenes, polyalkenes or unsaturated ketones in biobased ionic liquids are developed.
Keywords
- ionic liquids
- biomass
- hydrogenation
- transition metal-based catalysts
- alkenes
- (poly)-unsaturated alkenes
- α
- β-unsaturated ketones
- mild conditions
1. Introduction
Hydrogenation reactions of unsaturated compounds have been among the most extensively studied processes in catalysis for many years [1, 2]. To process, generally metallic catalysts are required. Nevertheless, one of the principal challenges facing the field of transition metal catalysis is the efficient recycling and the possibility to reuse the catalytic species.
Ionic liquids (ILs) were rapidly considered as very promising solvents for this purpose, due to their tunable physicochemical properties and capacity to immobilise catalysts. As their name indicates, ILs are ionic species containing an organic cation and presenting usually low melting points below 100°C [3, 4]. ILs have a negligible vapour pressure, are not so viscous over a wide temperature range and many are non-flammable [5]. Chemical and physical properties of ILs can be also refined through proper choice of cation and anion. For these reasons, ILs have been intensively investigated for the last three decades as green alternatives to conventional organic solvents [6–8]. Indeed, their numerous properties confer to these compounds the opportunity to replace classical organic solvents and their fields of applications are numerous: electrochemistry, organic synthesis, catalysis, complexation, extraction, etc. [4]. However, their low biodegradability or the toxicity of their degradation products and their high (eco)toxicity led the scientific community to reduce their use or to find other greener alternatives [9–13]. Considering this aspect, biobased ionic liquids could be a good alternative to classical ionic liquids but their preparation remains relative long and costly [14].
This chapter will be dedicated to the description of hydrogenation procedures of (poly)-alkenes or unsaturated ketones in biobased ionic liquids (ILs). In order to present this specific topic, the first part of the chapter will present the preparation of various biobased ionic liquids. Next, general procedures of hydrogenation in “classical” ILs will be developed according to recently published reviews. Finally, we will show that hydrogenation processes could be performed in biobased ILs with few examples.
2. Biobased ionic liquids
Due to their biodegradability and non-toxicity, the use of renewable resources could improve the green character of ILs. Among biobased precursors, building blocks such as amino acids [15] and amino alcohols from proteins, sugars from cellulose, chitin, starch and other polysaccharides, aromatic aldehydes from lignin and other compounds like fatty acids from vegetable or algae-derived oils can be used.
Amino acids or esters have been commonly used for the preparation of cations through classical acidification reaction or esterification/anionic metathesis sequences [16, 17]. The syntheses of all these ILs are summarised in Scheme 1. Protic or aprotics ILs could also be prepared, but their stability under acidic conditions was not suitable. One interesting example of such IL was presented by Trivedi et al. in which the counter anion was a sodium lauryl sulphate [18].
N-Heterocyclic amino acid-derived [19] chiral imidazolium based on valine, leucine and alanine [20], 4,5-dihydrothiazolium derived from biobased amino alcohol [21] and chiral pyrrolidine-based ILs from proline [22, 23] have been also prepared by synthetic ways involving more than four reaction steps. Gathergood et al. proposed some ILs with a neutral amino acid side chain that showed improvement on biodegradability [24]; they described also very recently L-phenylalanine ethyl ester ILs and non-ionic derivatives [25], and a series of amino acid derived ionic liquids showing microbial toxicity and biodegradation [26]. In addition, one of these last ILs presented the advantage to have antimicrobial properties. Betaine or betaine derivatives (Scheme 2) could be also transformed into ionic liquids, which can be used in extraction processes [27] or as herbicidal compounds [28]. Recently, de Almeida Meirelles et al. reviewed the use of ILs for food and bioproducts Industries; the authors suggested that biobased ILs could be use in food processes, especially when derived from amino acids or choline, and that moreover, their biocompatibility could even improve the methods [29].
Aminoacids could as well be used to build the anionic part of the ILs. They are commonly associated with imidazolium, ammonium or phosphonium cations (Scheme 2) [30, 31].
In our group, an acido-basic method was used to form various ILs with anion from natural acids (L-lactic, L-tartaric, pyruvic, malic, malonic, succinic and osidic acids), but also L-proline and its derivatives. Even they were not readily biodegradable, these compounds showed in general lower toxicity towards various organisms than usual chlorinated and commercial ILs (Scheme 3) [32].
Concerning the sugar family, these starting materials were essentially used to build cations. Fructose [33], glucose [34, 35], arabinose [36], isomannide [37] or isosorbide [38] have been transformed through multistep reactionnal pathways (Scheme 4). The resulting ILs were mainly used as chiral agents and presented in general low decomposition temperatures.
Our group developed particularly xylose-derived ILs wearing a triazolium group. They were obtained by click chemistry between alcynated xylose and azido alkyls or benzyl, followed by methylation [39] (Scheme 5). Positive glass transition and low decomposition temperatures were observed, which seemed to be in relation with the presence of sugar moieties. Considering these temperatures, these ILs could only be used under mild conditions as solvents or chiral agents for chemical transformations or catalysis.
Lipids represent also biosourced compounds, which could generate both cations and anions for ILs. Even if imidazolium-wearing oleic and stearic chain were easily prepared [40], the major utilisation of these lipids concerned the formation of anions, which were next associated with ammonium or phosphonium cations (Figure 1) [41].
Hulsbosch et al. described more exotic examples of bioresources for ILs as ephedrine or ampicillin in a recent and quite complete review dedicated to biobased ionic liquids for industry processing (Scheme 6) [14].
3. Hydrogenation in ionic liquids
Research into catalytic hydrogenations in ILs began in 1995 with the almost simultaneous work of Chauvin [42] and Dupont [43]. Since, catalytic reactions involving metal complexes in ILs have been actively investigated. Around 300 ILs have been screened and have led to the production of useful products and intermediates [44–46]. The majority of these ILs contained heterocyclic cations, such as pyridinium, imidazolium and polyalkylammonium and recently, synthesized guanidinium, piperidinium, pyrrolium, pyrrolidinium, morpholinium, cholinium, piperazinium and thiazolium. Other ILs had bridged structures, binuclear or polynuclear, zwitterionic, hydrophobic (fluorinated) and chiral derivatives [47].
Gathergood et al. wrote, in 2011, a big chapter entirely dedicated to hydrogenation processes in ILs [48]. This chapter is quite complete. For each hydrogenation reaction reviewed, catalysts and ILs are noted, together associated with the nature of the substrate. A section describing kinetic and thermodynamic studies of hydrogenations in ILs is also presented, as well as the solubility of H2 in many solvents and ILs under 1 atm. Some relevant examples have been identified from this chapter exclusively based on the use of H2 and catalysts (metal complexes or nanoparticles) in ILs.
Concerning the use of transition metal-based catalyst, various Ru- or Rh-based catalysts were used for the hydrogenation of halonitrobenzenes [49], cinnamaldehyde [50], cyclohexanone [51] or hexane [52] in 1-butyl-3-methylimidazolium hexafluorophosphate (bmim PF6) (Scheme 7).
For these last compounds, Pt- or Pd-based complexes could also be used [53] as well as for the hydrogenation of benzene [54] or benzene derivatives [55] pyridinium ILs (Scheme 8).
PdCl2 was also used by Gathergood et al. [56] in imidazolium ILs, including a readily biodegradable IL [(3-methyl-1-pentoxycarbonylmethyl)imidazolium octylsulphate], for the selective hydrogenation of phenoxyocta-2,7-diene under mild conditions (Scheme 9).
Concerning the asymmetric hydrogenation leading to enantiomerically pure products [57], the source of chiral induction was generally due to the presence of chiral ligands (BINAP or BINAP derivatives) coordinated to a metal catalyst [58–61], Rh- and Ru-based catalysts being generally the favourite candidates [48].
Metallic nanoparticles (NPs) could also be very useful for the hydrogenation processes. However, the knowledge about their formation and stabilisation for hydrogenation reactions in ILs is relatively new [62]. Pd [63, 64], Pt [65], Ir [66, 67], but also mixed Pd/Au NPs [68] were commonly used for (selective) hydrogenation of (poly)alkenes, while Ru-[69] and Ni-NPs [70] remained quite rare and were used for selective or complete hydrogenation of alkenes or arenes in imidazolium ILs (Scheme 10).
Scheeren et al. showed the formation of stable and isolable Pt(0)-NPs by reacting Pt2(dba)3 in 1-n-butyl-3-methylimidazolium hexafluorophosphate Bmim PF6 with molecular hydrogen (4 atm) at 75°C [65]. These NPs were very efficient for the hydrogenation of diphenylacetylene in Si-functionalised ILs (Scheme 11).
4. Hydrogenation in biobased ionic liquids
In 2013, Ferlin et al. prepared easily and with good yields, biobased ionic liquids from natural organic-derived anions (L-lactate, L-tartrate, malonate, succinate, L-malate, pyruvate, D-glucuronate and D-galacturonate) by reaction between tetrabutylammonium hydroxide (TBA⋅OH) and an excess of the corresponding acid (Scheme 3) [32]. Toxicity assays towards a large panel of bacterial and fungal strains were performed. ILs containing D-glucuronate or D-galacturonate anions were the less toxic whereas TBA L-tartrate and TBA L-malate were the most toxic biomass derivatives. All ILs were less toxic to
These biobased ILs showed good performance and recyclability (until 10 runs without loss of activity) in catalytic selective hydrogenation of 1,5-cyclooctadiene into cyclooctene at room temperature under atmospheric H2 pressure. In these mild conditions, they were more suitable for selective hydrogenation than commercial imidazoliums or ammonium ILs, which gave cyclooctane as major product (Scheme 12) [32].
Proline was also used to prepare easily chiral ionic liquids (CILs) tetrabutylammonium-(S)-prolinate, tetrabutylammonium-(R)-prolinate and tetrabutylammonium trans-4-hydroxy-(S)-prolinate from aminoacid, still by acido-basic reaction with tetrabutylammonium hydroxide (TBA⋅OH). While all three CILs have low antimicrobial toxicity to a wide range of bacteria and fungi, they did not pass the closed Bottle biodegradation test (Scheme 13) [71].
The hydrogenation of double carbon-carbon bonds of α,β-unsaturated ketones was processed under mild conditions with PdCl2 as catalyst in the presence of a CIL and a co-solvent (Scheme 14) [71]. The best performance was achieved when isopropanol was used in a co-solvent/CIL ratio equal to 5. Total conversion of isophorone with an enantiomeric excess (ee) up to 47% was obtained, and recyclability of the system was observed for five cycles without loss of reactivity.
Enantioselective hydrogenation of others α,β-unsaturated ketones was studied in the same mild conditions. Considering the particularly mild conditions, it was found that the method was very effective and competitive by comparison with previous works. Total conversion of pulegone was obtained with a good diastereoisomeric excess (de). Conversion was also complete for (R)-carvone with a very high selectivity of 90%. Hydrogenation occurred in the two carbon-carbon double bonds and an important de of 73% was observed. In the case of progesterone and 4-cholest-3-one, reaction occurred with very good yields and de, especially for 4-cholest-3-one.
Finally, concerning the field of transfer hydrogenation (so without the use of metallic species), γ-valerolactone-based ionic liquids (GVL-ILs) containing hydroxyvalerate anion were prepared according acid base reaction (Scheme 15) [72]. Theses ILs were successfully applied as alternative solvents for homogenous catalytic transfer hydrogenation of acetophenone and its substituted forms, but also of functionalised ketones and alkenes.
A series of GVL-based ILs associated with tetraalkylammonium cations were tested. Structure of the cation had negligible influence on the catalytic activity. The potential recyclability of the catalytic system was demonstrated in four consecutive cycles, especially for the reduction of acetophenone. The highest conversions were achieved by using [Rh(cod)2]+[BF4]− as catalyst precursor and formic acid as hydrogen donor. The optimal reaction conditions were 80°C and a molar ratio of HCOOH/substrate between 5:1 and 6:1 (Scheme 16) [73].
5. Conclusion
ILs are good solvents or co-solvent for metallic induced hydrogenation reactions. At first, their physical-chemical properties can be tunable depending on the anion-cation association. Consequently, the appropriate IL has to be simply chosen/found for the studied reaction. In addition, ILs are highly thermically stable, which is an advantage in the case of high-temperature hydrogenation reactions. The more important points are that they present good solubility of hydrogen and they are able to solubilise and stabilise metallic catalysts. As a consequence, they can promote hydrogenation reactions in mild conditions, sometimes the selectivity of the reaction, and/or they can allow the recyclability of the catalyst.
Hydrogenation in “usual” ILs has been performed on various unsaturated and aromatic substrates with various metallic catalysts or nanoparticles. In general, satisfying conversions and/or yields were observed. These reactions mainly used imidazoliums derivatives. They are the more common ILs, but also present (eco)toxicity and are not biodegradable.
To contour this problem, biobased and green ILs can be used. These compounds can be easily obtained from different biomass, such as amino acid, acids from bioprocess, carbohydrates or fatty oils. Despite their low biodegradability at the moment, they present in general lower (eco)toxicity than the commercials ILs. Similar to the “usual” ILs, biobased ILs are ideal solvent for hydrogenation reaction and can even bring improvements. When used as co-solvent, ammonium biobased ILs showed better selectivity and recyclability for 1,5-cyclooctadiene hydrogenation into cyclooctene in mild conditions than commercial ILs. Also biobased ILs can be chiral, brought by the chirality of their biobased building blocks, and be used for enantioselective hydrogenation reactions. With prolinate ILs, isophorone and carvone were hydrogenated in mild conditions with a good enantiomeric and diastereoisomeric excess, respectively. Transfer hydrogenation reactions were also recently investigated with biobased ILs. High conversion of acetophenone was achieved in the presence of γ-valerolactone-derived ILs, and the systems were reused four times without loss of reactivity.
Even if improvement needs to be made, especially for biodegradability of the compounds and simplification of their synthesis, biobased ILs seem to be good solvents, not only for hydrogenation reaction, but also for a wide range of chemical transformations (coupling reactions, oxidation, etc.). Moreover, with the increasing interest of valorisation of the biomass and the need to replace compounds derived from oil, new structures and applications of biobased ILs are expected for a near future.
Acknowledgments
This work was supported by the Fondation du Site Paris Reims (post doctoral fellowship for Nadège Ferlin) and the FEDER for material funds. We thank also the Tunisian Ministry of Education and Research for financial support for the cotutoring PhD of Safa Hayouni.
References
- 1.
Chaloner PA, Esteruleas MA, Joó F, Oro L. Homogeneous Hydrogenation, Catalysis by Metal Complexes, vol 15, Springer, Netherlands, 1994. 290 p. doi:10.1007/978-94-017-1791-5 - 2.
Oro L. Hydrogenation–Homogeneous, in Encyclopedia of Catalysis, Horváth IT editor. John Wiley & Sons, Hoboken, New Jersey, 2002. doi:10.1002/0471227617.eoc113 - 3.
Holbrey JD, Seddon KR. Ionic Liquids. Clean Prod Process 1999; 1: 223-236. DOI: 10.1007/s100980050036 - 4.
Wassercheid P, Welton T. Ionic Liquids in Synthesis. 2nd edition, Wiley-VCH, Weinheim, 2008. 721 p. doi:10.1002/9783527621194. - 5.
Stark A, Seddon KR. Ionic liquids. Kirk-Othmer Encyclopedia of Chemical Technology. Seidel A editor. John Wiley & Sons, Inc., New York. 2007; 26 :836–920. doi:10.1002/0471238961.ionisedd.a01. - 6.
Plechkova NV, Seddon KR. Applications of ionic liquids in the chemical industry. Chem Soc Rev. 2008; 37 (1):123–150. doi:10.1039/B006677J - 7.
Welton T. Room-temperature ionic liquids. Solvents for synthesis and catalysis. Chem Rev. 1999; 99 (8):2071–2084. doi:10.1021/cr9800032t - 8.
Endres F, Zein El Abedin S. Air and water stable ionic liquids in physical chemistry. Phys Chem Chem Phys. 2006; 8 (18):2101–2116. doi:10.1039/B600519P - 9.
Deng Y, Beadham I, Ghavre M, Costa Gomes MF, Gathergood N, Husson P, Legeret B, Quilty B, Sancelme M, Besse-Hoggan P. When can ionic liquids be considered readily biodegradable? Biodegradation pathways of pyridinium, pyrrolidinium and ammonium-based ionic liquids. Green Chem. 2015; 17 (3):1479–1491. doi:10.1039/C4GC01904K - 10.
Jordan A, Gathergood N. Biodegradation of ionic liquids—a critical review. Chem Soc Rev. 2015; 44 :8200–8237. doi:10.1039/C5CS00444F - 11.
Docherty KM, Kulpa Jr CF. Toxicity and antimicrobial activity of imidazolium and pyridinium ionic liquids. Green Chem. 2005; 7 (4):185–189. doi:10.1039/B419172B - 12.
Stolte S, Arning J, Bottin-Weber U, Matzke M, Stock F, Thiele K, Uerdingen M, Welz-Biermann U, Jastorff B, Ranke J. Anion effects on the cytotoxicity of ionic liquids. Green Chem. 2006; 8 :621–629. doi:10.1039/B602161A - 13.
Pretti C, Chiappe C, Pieraccini D, Gregori M, Abramo F, Monni G, Intorre L. Acute toxicity of ionic liquids to the zebrafish ( Danio rerio ). Green Chem. 2006;8 :238–240. doi:10.1039/B511554J - 14.
Hulsbosch J, De Vos DE, Binnemans K, Ameloot R. Bio-based ionic liquids: solvents for a green processing industry? ACS Sustain Chem Eng. 2016; 4 (6):2917–2931. doi:10.1021/acssuschemeng.6b00553 - 15.
Plaquevent JC, Levillain J, Guillen F, Malhiac C, Gaumont AC. Ionic liquids: new targets and media for alpha-amino acid and peptide chemistry. Chem Rev. 2008; 108 (12):5035–5060. doi:10.1021/cr068218c - 16.
Tao G, He L, Sun N, Kou Y. New generation ionic liquids: cations derived from amino acids. Chem Commun. 2005; 28 :3562–3564. doi:10.1039/c0cc00028k - 17.
He L, Tao GH, Parrish DA, Shreeve JM. Slightly viscous amino acid ionic liquids: synthesis, properties, and calculations. J Phys Chem B. 2009; 113 (46):15162–15169. doi:10.1021/jp905079e - 18.
Trivedi TJ, Rao KS, Singh T, Mandal SK, Sutradhar N, Panda AB, Kumar A. Task‐specific, biodegradable amino acid ionic liquid surfactants. ChemSusChem. 2011; 4 (5):604–608. doi:10.1002/adsc.201401010 - 19.
Wasserscheid P, Bösmann A, Bolm C. Synthesis and properties of ionic liquids derived from the chiral pool. Chem Commun. 2002; 3 :200–201. doi:10.1039/B109493A - 20.
Clavier H, Boulanger L, Audic N, Toupet L, Mauduit M, Guillemin JC. Design and synthesis of imidazolinium salts derived from (L)-valine. Investigation of their potential in chiral molecular recognition. Chem Commun. 2004:1224–1225. doi:10.1039/B402368D - 21.
González L, Altava B, Bolte M, Burguete MI, García-Verdugo E, Luis SV. Synthesis of chiral room temperature ionic liquids from amino acids – application in chiral molecular recognition. Eur J Org Chem. 2012;2 6 :4996–5009. doi:10.1002/ejoc.201200607 - 22.
Bao W, Wang Z, Li Y. Synthesis of chiral ionic liquids from natural amino acids. J Org Chem. 2003; 68 (2):591–593. doi:10.1021/jo020503 - 23.
Luo S, Mi X, Zhang L, Liu S, Xu H, Cheng JP. Functionalized chiral ionic liquids as highly efficient asymmetric organocatalysts for Michael addition to nitroolefins. Angew Chem Int Ed. 2006; 45 :3093–3097.doi:10.1002/anie.200600048 - 24.
Coleman D, Špulák M, Garcia MT, Gathergood N. Antimicrobial toxicity studies of ionic liquids leading to a ‘hit’ MRSA selective antibacterial imidazolium salt. Green Chem. 2012; 14 :1350–1356. doi:10.1039/C2GC16090K - 25.
Haiß A, Jordan A, Westphal J, Evgenia Logunova E, Gathergood N, Kümmerer K. On the way to greener ionic liquids: identification of a fully mineralizable phenylalanine-based ionic liquid. Green Chem. 2016; 18 :4361–4373. doi:10.1039/c6gc00417b - 26.
Jordan A, Haiß A, Spulak M, Karpichev Y, Kümmerer K, Gathergood N. Synthesis of a series of amino acid derived ionic liquids and tertiary amines: green chemistry metrics including microbial toxicity and preliminary biodegradation data analysis. Green Chem. 2016; 18 :4374–4392. doi:10.1039/c6gc00415f - 27.
De Gaetano Y, Hubert J, Mohamadou A, Boudesocque S, Plantier-Royon R, Renault JH, Dupont L. Removal of pesticides from wastewater by ion pair centrifugal partition extraction using betaine-derived ionic liquids as extractants. Chem Eng J. 2016; 285 :596–604. doi:10.1016/j.cej.2015.10.012 - 28.
Pernak J, Niemczak M, Chrzanowski L, Ławniczak L, Fochtman P, Marcinkowska K, Praczyk T. Betaine and carnitine derivatives as herbicidal ionic liquids. Chem Eur J. 2016; 22 :12012–12021. doi:10.1002/chem.201683462 - 29.
Campos Toledo Hijo AA, Maximo GJ, Costa MC, Caldas Batista EA, de Almeida Meirelles AJ. Applications of ionic liquids in the food and bioproducts industries. ACS Sustain Chem Eng. 2016.doi:10.1021/acssuschemeng.6b00560 - 30.
Kagimoto J, Fukumoto K, Ohno H. Effect of tetrabutylphosphonium cation on the physico-chemical properties of amino-acid ionic liquids. Chem Commun. 2006; 4 ;(21):2254–2256. doi:10.1039/b600771f - 31.
Fukumoto K, Ohno H. Design and synthesis of hydrophobic and chiral anions from amino acids as precursor for functional ionic liquids. Chem Commun. 2006:3081–3083. doi:10.1039/B606613E - 32.
Ferlin N, Courty M, Gatard S, Spulak M, Quilty B, Beadham I, Ghavre M, Haiß A, Kümmerer K, Gathergood N, Bouquillon S. Biomass derived ionic liquids: synthesis from natural organic acids, characterization, toxicity, biodegradation and use as solvents for catalytic hydrogenation processes. Tetrahedron. 2013; 30 :6150–6161. doi:10.1016/j.tet.2013.05.054 - 33.
Handy ST, Okello M, Dickenson G. Solvents from biorenewable sources: ionic liquids based on fructose. Org Lett. 2003; 5 (14):2513–2515. doi:10.1021/ol034778b - 34.
Jha AK, Jain N. Synthesis of glucose-tagged triazolium ionic liquids and their application as solvent and ligand for copper(I) catalyzed amination. Tetrahedron Lett. 2013; 54 (35):4738–4741. doi:10.1016/j.tetlet.2013.06.114 - 35.
Poletti L, Chiappe C, Lay L, Pieraccini D, Polito L, Russo G. Glucose-derived ionic liquids: exploring low-cost sources for novel chiral solvents. Green Chem. 2007; 9 :337–341. doi:10.1039/B615650A - 36.
Chiappe C, Marra A, Mele A. Synthesis and applications of ionic liquids derived from natural sugars. Top Curr Chem. 2010; 295 :177–195. doi:10.1007/128_2010_47 - 37.
Kumar V, Pei C, Olsen CE, Schäffer SJC, Parmar V, Malhotra SV. Novel carbohydrate-based chiral ammonium ionic liquids derived from isomannide. Tetrahedron: Asymmetry. 2008; 19 (6);2008 :664–671. doi:10.1016/j.tetasy.2008.02.009 - 38.
Nguyen Van Buu O, Aupoix A, Doan Thi Hong N, Vo-Thanh G. Chiral ionic liquids derived from isosorbide: synthesis, properties and applications in asymmetric synthesis. New J Chem. 2009; 33 :2060–2072. doi:10.1039/B902956G - 39.
Ferlin N, Gatard S, Nguyen Van Nhien A, Courty M, Bouquillon S. Click reactions as a key step for an efficient and selective synthesis of D -xylose-based ILs. Molecules. 2013;18 (9):11512–11525. doi:10.3390/molecules180911512 - 40.
Kwan ML, Mirjafari A, McCabe JR, O’Brien RJ, Essi IV DF, Baum L, West KN, Davis Jr JH. Synthesis and thermophysical properties of ionic liquids: cyclopropyl moieties versus olefins as Tm-reducing elements in lipid-inspired ionic liquids. Tetrahedron Lett. 2013; 54 (1):12–14. doi:10.1016/j.tetlet.2012.09.101 - 41.
Parmentier D, Metz SJ, Kroon MC. Tetraalkylammonium oleate and linoleate based ionic liquids: promising extractants for metal salts. Green Chem. 2013; 15 :205–209. doi:10.1039/C2GC36458A - 42.
Chauvin Y, Mussmann L, Olivier H. A novel class of versatile solvents for two-phase catalysis: hydrogenation, isomerization, and hydroformylation of alkenes catalyzed by rhodium complexes in liquid 1,3-dialkylimidazolium salt. Angew Chem Int Ed. 1995; 34 :2698–2700. doi:10.1002/anie.199526981 - 43.
Suarez AZP, Dullius ELJ, Einloft S, De Souza FR, Dupont J. The use of new ionic liquids in two-phase catalytic hydrogenation reaction by rhodium complexes. Polyhedron. 1996; 15 :1217–1219. doi:10.1016/0277-5387(95)00365-7 - 44.
Sheldon RA, Arends I, Hanefeld U, editors. Green chemistry and catalysis. John Wiley & Sons, Wiley-VCH Verlag GmbH & Co, Weinheim, 2007. 448 p. DOI: 10.1002/9783527611003 - 45.
Augustine RL: Heterogeneous catalysis for the synthetic chemist. CRC Press, Marcel Dekker, Inc., New York. 1995.672 p. ISBN 0-8247-9021-9. - 46.
Beletskaya IP, Kustov LM. Catalysis as an important tool of green chemistry. Russ Chem Rev. 2010; 79 (6):441–461. doi:10.1070/RC2010v079n06ABEH004137 - 47.
Wasserscheid P, Keim W. Ionic liquids—new “solutions” for transition metal catalysis. Angew Chem Int Ed. 2000; 39 :3772–3789. doi:10.1002/1521-3773(20001103)39:21<3772::AID-ANIE3772>3.0.CO;2-5. - 48.
Ghavre M, Morrissey S, Gathergood N. Hydrogenation in Ionic Liquids, Ionic Liquids: Applications and Perspectives. Kokorin A editor. CC BY-NC-SA 3.0 license. InTech; 2011. 331-392. DOI: 10.5772/14315 - 49.
Xu D, Hu Z, Li W, Luo S, Xu Z. Hydrogenation in ionic liquids: an alternative methodology toward highly selective catalysis of halonitrobenzenes to corresponding haloanilines. J Mol Catal A. 2005; 235 :137–142. doi:10.1016/j.molcata.2005.04.004 - 50.
Arras J, Steffan M, Shayeghi Y, Claus P. The promoting effect of a dicyanamide based ionic liquid in the selective hydrogenation of citral. Chem Commun. 2008;4058–4060. doi:10.1039/B810291K - 51.
Wolfson A, Vankelecom I, Jacobs P. Beneficial effect of water as second solvent in ionic liquid biphasic catalytic hydrogenations. Tetrahedron Lett. 2005; 46 :2513–2516. doi:10.1016/j.tetlet.2005.01.179 - 52.
Suarez T, Fontal B, Reyes M, Bellandi F, Contreras R, Ortega J, Leon G, Cancines P, Castillo B. Catalytic Hydrogenation of 1-Hexene with RuCI2 (TPPMS)3(DMSO). Part II: ionic liquid biphasic system. React Kinet Catal Lett. 2004; 82 :325–331. doi:10.1023/B%3AREAC.0000034844.21731.7f - 53.
Arras J, Steffan M, Shayeghi Y, Ruppert D, Claus P. Regioselective catalytic hydrogenation of citral with ionic liquids as reaction modifiers. Green Chem. 2009; 11 :716–723. doi:10.1039/B822992A - 54.
Geldbach T, Dyson P. Searching for molecular arene hydrogenation catalysis in ionic liquids. J Organomet Chem. 2005; 690 :3552–3557. doi:10.1016/j.jorganchem.2005.03.006 - 55.
Hardacre C, Mullan E, Rooney D, Thompson J, Yablonsky G. Comparison of mass transfer effects in the heterogeneously catalysed hydrogenation of phenyl acetylene in heptane and an ionic liquid. Chem Eng Sci. 2006; 61 :6995–7006. doi:10.1016/j.ces.2006.07.020 - 56.
Bouquillon S, Courant T, Dean D, Gathergood N, Morrissey S, Pegot B, Scammells PJ, Singer R. Biodegradable ionic liquids: selected synthetic applications. Aust J Chem. 2007; 60 :843–847. doi:10.1071/CH07257. - 57.
Blaser HU, Malan C, Pugin B, Spindler F, Steiner H, Studer M. Selective hydrogenation for fine chemicals: recent trends and new developments. Adv Synth Catal. 2003; 345 :103–151. doi:10.1002/adsc.200390000 - 58.
Noyori R, Kitamura M, Ohkuma T. Toward efficient asymmetric hydrogenation: architectural and functional engineering of chiral molecular catalysts. PNAS. 2004; 101 :5356–5362. doi:10.1073/pnas.0307928100 - 59.
Bautista F, Caballero V, Campelo J, Luna D, Marinas J, Romero A, Romero I, Serrano I, Llobet A. Heterogeneization of a new Ru(II) homogeneous asymmetric hydrogenation catalyst containing BINAP and the N-tridentate bpea ligand, through covalent attachment on amorphous AlPO4 support. Top Catal. 2006; 40 :193–205. doi:10.1038/nchem.216 - 60.
Chan SA, Laneman SA, Day C. Preparation and structural characterization of bis(acetylacetonato)ruthenium(II)-BINAP: an efficient route to an effective asymmetric hydrogenation catalyst precursor. Inorg Chim Acta. 1995; 228 :159–163. doi:10.1016/0020-1693(94)04167-T - 61.
Wan DK, Davis M. Ruthenium (II)-sulfonated BINAP. A novel water-soluble asymmetric hydrogenation catalyst. Tetrahedron: Asymmetry. 1993; 4 :2461–2468. doi:10.1016/S0957-4166(00)82224-7 - 62.
Scheeren CW, Domingos JB, Machado G, Dupont J. Hydrogen reduction of Adams’ catalyst in ionic liquids: formation and stabilization of Pt(0) nanoparticles. J Phys Chem C. 2008; 112 :16463–16469. doi:10.1021/jp804870j - 63.
Umpierre A, Machado G, Fecher G, Morais J, Dupont J. Selective hydrogenation of 1,3-butadiene to 1-butene by Pd(0) nanoparticles embedded in imidazolium ionic liquids. Adv Synth Catal. 2005; 347 :1404–1412. doi:10.1002/adsc.200404313 - 64.
Huang J, Jiang T, Han B, Gao H, Chang Y, Zhao G, Wu W. Hydrogenation of olefins using ligand-stabilized palladium nanoparticles in an ionic liquid. Chem Commun. 2003:1654–1655. doi:10.1039/B302750C - 65.
Scheeren C, Machado G, Dupont J, Fichtner P, Texeira S. Nanoscale Pt(0) particles prepared in imidazolium room temperature ionic liquids: synthesis from an organometallic precursor, characterization, and catalytic properties in hydrogenation reactions. Inorg Chem. 2003; 42 :4738–4742. doi:10.1021/ic034453r - 66.
Fonseca G, Domingos J, Nome F, Dupont J. On the kinetics of iridium nanoparticles formation in ionic liquids and olefin hydrogenation. J Mol Catal A. 2006; 248 :10–16. doi:10.1016/j.molcata.2005.12.002 - 67.
Dupont J, Fonseca G, Umpierre A, Fichtner P, Teixeira S. Transition-metal nanoparticles in imidazolium ionic liquids: recycable catalysts for biphasic hydrogenation reactions. J Am Chem Soc. 2002; 124 :4228–4229. doi:10.1021/ja025818u - 68.
Dash P, Dehm N, Scott R. Bimetallic PdAu nanoparticles as hydrogenation catalysts in imidazolium ionic liquids. J Mol Catal A: Chem. 2008; 286 :114–119. doi:10.1016/j.molcata.2008.02.003 - 69.
Prechtl M, Scariot M, Scholten J, Machado G, Teixeira S, Dupont J. Nanoscale Ru(0) particles: arene hydrogenation catalysts in imidazolium ionic liquids. Inorg Chem. 2008; 47 :8995–9001. doi:10.1021/ic801014f - 70.
Migowski P, Machado G, Texeira S, Alves M, Morais J, Traverse A, Dupont J. Synthesis and characterization of nickel nanoparticles dispersed in imidazolium ionic liquids. Phys Chem. 2007; 9 :4814–4821. doi:10.1039/B703979D - 71.
Ferlin N, Courty M, Nguyen Van Nhien A, Gatard S, Pour M, Quilty B, Ghavre M, Haiß A, Kümmerer K, Gathergood N, Bouquillon S. Tetrabutylammonium prolinate-based ionic liquids: a combined asymmetric catalysis, antimicrobial toxicity and biodegradation assessment. RSC Adv. 2013; 3 :26241–26251. doi:10.1039/C3RA43785J - 72.
Strádi A, Molnár M, Óvári M, Dibó G, Richter FU, Mika L. Rhodium-catalyzed hydrogenation of olefins in γ-valerolactone-based ionic liquids. Green Chem. 2013; 15 (7):1857–1862. doi:10.1039/C3GC40360B - 73.
Strádi A, Molnár M, Szakál P, Dibó G, Gáspár D, Mika LT. Catalytic transfer hydrogenation in γ-valerolactone-based ionic liquids. RSC Adv. 2015; 5 (89):72529–72535. doi:10.1039/C5RA12657F