Friedel–Crafts reactions in room temperature ionic liquids

Earle, Martyn J.; Seddon, Kenneth R.; Adams, Christopher J.; Roberts, Graham

doi:10.1039/a805599h

Cited by 106 publications

(38 citation statements)

References 15 publications

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“…Among the key applications of liquid-ionic liquid biphasic catalysis with acidic chloroaluminate ILs are Friedel-Crafts alkylation [26][27][28][29], Friedel-Crafts acylation [30][31][32] and carbonylation reactions [33][34][35]. Other important acid catalyzed reactions that have been successfully carried out in form of liquid-ionic liquid biphasic catalysis include oligomerization [36], cracking [37,38] and refinery alkylation reactions [39][40][41].…”

Section: Liquid-ionic Liquid Biphasic Catalysis Usingmentioning

confidence: 99%

Ionic Liquids in Catalysis

2014

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Ionic liquids (ILs), salts with melting points below 100°C, represent a fascinating class of liquid materials typically characterized by an extremely low vapor pressure. Besides their application as new solvents or as electrolytes for electrochemical purposes, there are two important concepts of using ILs in catalysis: Liquid-liquid biphasic catalysis and IL thin film catalysis. Liquid-liquid biphasic catalysis enables either a very efficient manner to apply catalytic ILs, e.g. in Friedel-Crafts reactions, or to apply ionic transition metal catalyst solutions. In both cases, phase separation after reaction allows an easy separation of reaction products and catalyst re-use. One problem of liquidliquid biphasic catalysis is mass transfer limitation. If the chemical reaction is much faster than the liquid-liquid mass transfer the latter limits the overall reaction rate. This problem is overcome in IL thin film catalysis where diffusion pathways and thus the characteristic time of diffusion are short. Here, Supported Ionic Liquid Phase (SILP) and Solid Catalyst with Ionic Liquid Layer (SCILL) are the two most important concepts. In both, a high surface area solid substrate is covered with a thin IL film, which contains either a homogeneously dissolved transition metal complex for SILP, or which modifies catalytically active surface sites at the support for SCILL. In each concept, interface phenomena play a very important role: These may concern the interface of an IL phase with an organic phase in the case of liquidliquid biphasic catalysis. For IL thin film catalysis, the interfaces of the IL with the gas phase and with catalytic nanoparticles and/or support materials are of critical importance. It has recently been demonstrated that these interfaces and also the bulk of ILs can be investigated in great detail using surface science studies, which greatly contributed to the fundamental understanding of the catalytic properties of ILs and supported IL materials. Exemplary results concerning the IL/vacuum or IL/gas interface, the solubility and surface enrichment of dissolved metal complexes, the IL/support interface and the in situ monitoring of chemical reactions in ILs are presented.

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Section: Liquid-ionic Liquid Biphasic Catalysis Usingmentioning

confidence: 99%

Ionic Liquids in Catalysis

2014

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“…Lewis acidic ionic liquids containing the chloroaluminate anions AlCl 4 − and Al 2 Cl 7 − have been successfully used as acid catalysts in a range of reactions including Friedel-Crafts [88][89][90] , dimerisation, cracking and isomerisation reactions [89] . Besides the chloroaluminates, ionic liquids with higher stability in the presence of water have also been used as acid catalysts [91,92] .…”

Section: Advantages As Solventsmentioning

confidence: 99%

Ionic Liquids in Biomass Processing

Tan

MacFarlane

2009

Topics in Current Chemistry

115

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Ionic liquids have been studied for their special solvent properties in a wide range of processes, including reactions involving carbohydrates such as cellulose and glucose. Biomass is a widely available and renewable resource that is likely to become an economically viable source of starting materials for chemical and fuel production, especially with the price of petroleum set to increase as supplies are diminished. Biopolymers such as cellulose, hemicellulose and lignin may be converted to useful products, either by direct functionalisation of the polymers or depolymerisation to monomers, followed by microbial or chemical conversion to useful chemicals. Major barriers to the effective conversion of biomass currently include the high crystallinity of cellulose, high reactivity of carbohydrates and lignin, insolubility of cellulose in conventional solvents, as well as heterogeneity in the native lignocellulosic materials and in lignin itself. This combination of factors often results in highly heterogeneous depolymerisation products, which make efficient separation difficult. Thus the extraction, depolymerisation and conversion of biopolymers will require novel reaction systems in order to be both economically attractive and environmentally benign. The solubility of biopolymers in ionic liquids is a major advantage of their use, allowing homogeneous reaction conditions, and this has stimulated a growing research effort in this field. This review examines current research involving the use of ionic liquids in biomass reactions, with perspectives on how it relates to green chemistry, economic viability, and conventional biomass processes.

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“…3 The conventional catalysts for the cyclotrimerization of aldehydes were protonic acid such as H 2 10 More recently, ionic liquids as an environmentally benign media for organic synthesis and catalytic reaction have been widely employed due to their properties such as negligible vapor pressure, high thermal stability, recyclability and tunable acidity. [11][12][13][14][15][16][17] To the best of our knowledge, the cyclotrimerization of aldehydes using ionic liquids as catalyst has not been reported.…”

Section: Introductionmentioning

confidence: 99%

Cyclotrimerization of Aliphatic Aldehydes Catalyzed by Ionic Liquids

Liu

Yang

et al. 2006

Chin. J. Chem.

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Aliphatic aldehydes such as ethanal, propanal, n-butanal, isobutyraldehyde, n-valeraldehyde, isovaleraldehyde, n-hexanal and n-octanal were converted into the corresponding 2,4,6-trialkyl-1,3,5-trioxanes through cyclotrimerization in the presence of the ferric chloride based ionic liquids at room temperature without solvent in high selectivity. The effects of different ionic liquids, acidity of ionic liquids and temperature on cyclotrimerization were also studied. The results showed that the ferric chloride based ionic liquids (apparent molar fraction of FeCl 3 (x(FeCl 3 )＝ 0.62)) were a kind of efficient catalysts for the cyclotrimerization of aliphatic aldehyde which could be separated conveniently from the reaction mixture and recycled without loss of catalytic activity. The conversion of isobutyraldehyde and the selectivity to 2,4,6-triisopropyl-1,3,5-trioxane were 91.1% and 99.8% respectively under optimum reaction condition (isobutyraldehyde 25.0 g, [Et 3 NH]Cl/FeCl 3 (x(FeCl 3 )＝0.62) 1.0 g, 25 ℃ for 1 h) .

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Friedel–Crafts reactions in room temperature ionic liquids

Cited by 106 publications

References 15 publications

Ionic Liquids in Catalysis

Ionic Liquids in Catalysis

Ionic Liquids in Biomass Processing

Cyclotrimerization of Aliphatic Aldehydes Catalyzed by Ionic Liquids

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