Reactions novel media

Some potential applications of dispersions of nanodroplets of such highly viscous solvents as novel reaction media for controlled synthesis have been investigated [236]. 

The Mizoroki-Heck reaction in liquid imidazolium salts as the solvent is a special case of an in situ system Under the reaction conditions NHC complexes of palladium are formed as the active catalyst from the solvent and the ligand-free palladium precursor. In general, ionic liquids are novel reaction media for homogeneous catalysis. They allow easy separation of product and catalyst after the reaction. ... 

Novel Reaction Media for Biocata lytic Tranformations I 363... 

This chapter focuses on the application of transition metal catalysts and enzymes for the formation of carbon-carbon bonds. Transition metal-catalyzed carbon-carbon bond formations are not always very green but they often replace even less favorable conventional approaches. The key to making them really green is that they have to be easily separable and reusable. Several of these reactions, such as the hydroformylation, oligomerisation, carbonylation of alcohols and the metathesis, are therefore also treated in Chapter 1, Section 1.8 and Chapter 7, since their greener variations are performed in novel reaction media. 

A number of very interesting applications namely chromatographic stationary phase, adsorbent, catalytic support, or mineral membrane can be achieved using ultrafine metal-oxide particles. Supercritical fluids have been investigated as suitable and novel reaction media for the synthesis of such particles starting from titanium alkoxide precursors [55]. 

Microemulsions provide ultralow interfacial tensions and large interfacial areas as well as the ability to concentrate and localize significant amounts of both oil-and water-soluble materials within the same isotropic medium. Over the years, attention has been focused on their potential use as novel reaction media for a wide range of chemical, biochemical, and photochemical reactions, and as carriers for chemicals and small particles, reviewed by Eccleston. Inverse microemulsions of the w/o type are the subject of particular interest because of the rapidly emerging range of... 

Abstract Room temperature ionic liquids (ILs) have attracted considerable attention as novel reaction media over the last decade. By virtue of their unique properties, ILs have been proposed as alternative solvents. Structurally, most of the ILs that have been investigated to date are based on imidazolium, pyridinium and ammonium cations, associated with polyatomic anions such as chloroaluminates, tetrafluoroborate, hexafluorophoshate and bis-triflimide. Although these salts have positive properties, imidazole, pyridine and halogenoalkanes come from petroleum feedstocks that are neither green nor sustainable. Renewable resources may represent a valid alternative to synthesized new ILs an alternative able to take into accounts both the ecological and economic requirements. 

Room temperatures ionic liquids (ILs)- salts with melting points below 100°C- have attracted considerable attention as novel reaction media over the last decade. By virtue of their nonflammability, thermal stability and non-volatility ionic liquids have been proposed as alternative solvents receiving serious consideration with the promise of both environmental and technological benefits. Really, recent data showing that commonly used ILs have very low but not null vapour pressures (they can distilled at low pressure), that a large group of ILs is combustible" and some commercially available ionic compoimds are toxic for some aquatic species, have cast a shadow on the "green character of ILs. The instinctive skepticism toward... 

Sheldon, R.A., Arends, l.W.C.E. and Hanefeld, U. (2007) Catalysis in novel reaction media, in Green Chemistry and Catalysis (eds R.A. Sheldon, 1. Arends and U. Hanefeld), Wiley-VCH Verlag, Weinheim. 

In view of the rapidly increasing importance of imidazolium-based ionic liquids as novel reaction media, use of 1 -butyl-3 -methylimidazolium tetrafluoroborate ([bmim] [BF ]) as a recyclable solvent and promoter for greener organic synthesis is attracted the attention of many organic chemists. 

In view of the emerging importance of the ionic liquids as novel reaction media, Yadav and his coworkers explored the use of ionic liquids as promoters for the synthesis of c -quinolonic acids. The reactions of various aldehydes, amines, and homophthalic anhydride were studied in different ionic hquids (Fig. 12.5) [4], Among these ionic liquids, [bmim][BF ] was found to be superior in terms of yields, reaction rates, and reusability. 

The simple experimental and product isolation procedures combined with ease of recovery and reuse of this novel reaction media contribute to the development of green strategy for the preparation of isoxazolidines. Furthermore, the use of [bmim] [PFg] solvent system for this transformation avoids the use of toxic or corrosive reagents and high temperature reaction conditions, and thus, it provides convenient procedure to carry out the reactions at ambient temperature. 

Li S, Lin Y, Xie H, Zhang S, Xu J (2006) Bronsted guanidine acid-base ionic liquids novel reaction media for the paUadium-cateilyzed heck reaction. Oig Lett 8 391-392... 

Clapes P, Caminal G, FeUu JA et al. (2000) Peptide synthesis in non-aqueous media. In Gupta MN (ed). Methods in non-aqueous enzymology. Birkhauser, Bassel, pp 110-132 Clapes P, Espelt L, Navarro M et al. (2001) Highly concentrated water-in-oil emulsions as novel reaction media for protease-catalysed kinetically controUed peptide synthesis. J Chem Soc Perk T 2 1394-1399... 

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