A review of ionic liquids: Applications towards catalytic organic transformations

Fourier Transform Infrared Spectroscopy: Applications to Chemical Systems Vol 1 Edited by J R Ferraro and L J Basile Pp 311 (Academic: New York, San Francisco and London, 1978) $25; £1625

Fourier transform infrared spectroscopy

Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition.

Acidic Ionic Liquids.

Recent advances in ionic liquid catalysis

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 liquid–liquid 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 liquid–liquid 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. Important concepts in catalysis with ionic liquids are reviewed, including Supported Ionic Liquid Phase (SILP) and Solid Catalyst with Ionic Liquid Layer (SCILL), along with the detailed analysis of the relevant interfaces using surface science methods.

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Ionic Liquids in Catalysis

High-quality bio-oil from one-pot catalytic hydrocracking of kraft lignin over supported noble metal catalysts in isopropanol system

In this article, a new group of SO3H-functionalized ionic liquids based on benzimidazolium cation was synthesized and used as environmentally benign catalysts for the one-pot synthesis of biscoumarin derivatives. The ionic liquids showed high catalytic activities and reusabilities with good to excellent yields of the desired products. H
 0 (Hammett function) values and the minimum-energy geometries of SO3H-functionalized ionic liquids were determined and the results revealed that the acidities and catalytic activities of ionic liquids in the synthesis of biscoumarin derivatives were related to their structures. The simple, more efficient way for synthesis of biscoumarin derivatives has been developed. This new method abandon the traditional hazardous organic liquid and is carried out by using a one-pot reaction of 4-hydroxycoumarin with aromatic aldehydes in the presence of novel SO3H-functionalized ionic liquids based on benzimidazolium cation as catalysts. The ionic liquids showed high catalytic activities and reusabilities with good to excellent yields of the desired products. H
 0 (Hammett function) values and the minimum-energy geometries of SO3H-functionalized ionic liquids were determined and the results revealed that the acidities and catalytic activities of ionic liquids in the synthesis of biscoumarin derivatives were influenced by their structures.

Novel SO3H-Functionalized Ionic Liquids Based on Benzimidazolium Cation: Efficient and Recyclable Catalysts for One-Pot Synthesis of Biscoumarin Derivatives

Novel Brønsted acidic ionic liquids based on benzimidazolium cation: Synthesis and catalyzed acetalization of aromatic aldehydes with diols

Soy protein concentrate was hydrothermally treated at isothermal temperatures of 200, 250, 300, and 350 °C for times up to 60 min to produce a crude bio-oil. Additional product fractions included water-soluble products, gases, and residual solids. We report herein the conversion of protein and gravimetric yields of the different product fractions. The biocrude yield generally increased with both time and temperature as did the yield of gaseous products. The highest biocrude yield was 34%, produced from liquefaction at 350 °C for 60 min. Chemical and physical characterization of the biocrude revealed how its composition and boiling point range changed with reaction time. Finally, we report a reaction network and the parameters for a phenomenological kinetics model that captures the influence of time and temperature on the yields of gas, solid, biocrude, and aqueous-phase products from isothermal hydrothermal liquefaction (HTL) of soy protein concentrate. The reaction network comprised a sole primary path, ...

https://pubs.acs.org/doi/pdf/10.1021/acssuschemeng.6b00226

Products and Kinetics for Isothermal Hydrothermal Liquefaction of Soy Protein Concentrate

Three-dimensional amine-terminated ionic liquid functionalized graphene/Pd composite aerogel as highly efficient and recyclable catalyst for the Suzuki cross-coupling reactions

Liyi Dai

Papers

High-quality bio-oil from one-pot catalytic hydrocracking of kraft lignin over supported noble metal catalysts in isopropanol system

Novel SO3H-Functionalized Ionic Liquids Based on Benzimidazolium Cation: Efficient and Recyclable Catalysts for One-Pot Synthesis of Biscoumarin Derivatives

Novel Brønsted acidic ionic liquids based on benzimidazolium cation: Synthesis and catalyzed acetalization of aromatic aldehydes with diols

Products and Kinetics for Isothermal Hydrothermal Liquefaction of Soy Protein Concentrate

Three-dimensional amine-terminated ionic liquid functionalized graphene/Pd composite aerogel as highly efficient and recyclable catalyst for the Suzuki cross-coupling reactions