Green solvents fluids , catalysis

Keywoids. Environmentally benign synthesis, Catalysis, Green solvents. Supercritical fluids. Carbon dioxide. 

The last two decades have seen an explosion of interest in ionic liquids [1]. Their use as solvents has been the subject of widespread academic study [2] and they have been applied in a number of commercial processes [3]. Much of the interest in ionic liquids has centered on their possible use as green solvents [4]. However, this has been the subject of much controversy [5], and the concept of a green solvent itself is now somewhat dated. There have been many reviews of ionic liquids. Some of these have focused on particular applications, for example, analysis [6], biocatalysis [7], catalysis [8], electrochemical devices [9], or engineering fluids [10]. Others have concentrated on particular subgroups of ionic liquids, for example, task-specific ionic liquids [11]. This chapter summarizes what is known about the physicochemical properties that are of particular interest for supported ionic hquid phases (SILPs). 

In answer to these limitations, research and development efforts of the last 20 years have tried to develop advanced liquid-liquid biphasic hydroformylation catalysis by replacing water by another catalyst solvent. As the number of organic-organic, biphasic systems with a sufficient miscibility gap in the presence of hydroformylation products is very limited, these efforts led to the application of so-called advanced fluids or green solvents in hydroformylation catalysis. Given the restricted scope of this textbook, it will be only possible to describe briefly the most important approaches and their scopes and limitations. The reader interested in the details of these dynamic research fields is referred to a series of recently published monographs (Mathison et al., 2006 Leitner and Jessop, 2010, and Stark and Wasserscheid, 2010). 

The replacement of relatively harmful volatile organic solvents with, alternative, less environmentally damaging solvent systems/approaches is generating interest from a green perspective for synthetic chemistry and catalysis. A number of these are reviewed elsewhere in this compilation. Here, we highlight some notable developments in green applications of water, supercritical (sc) fluids, ionic liquids, and fluorous solvents in organometallic chemistry. 

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