Designer solvent

Ionic liquids have been described as designer solvents [11]. Properties such as solubility, density, refractive index, and viscosity can be adjusted to suit requirements simply by making changes to the structure of either the anion, or the cation, or both [12, 13]. This degree of control can be of substantial benefit when carrying out solvent extractions or product separations, as the relative solubilities of the ionic and extraction phases can be adjusted to assist with the separation [14]. Also, separation of the products can be achieved by other means such as, distillation (usually under vacuum), steam distillation, and supercritical fluid extraction (CO2). 

Room-temperature ionic liquids have received much attention as green designer solvents. We first demonstrated that ionic liquids acted as good medium for lipase-catalyzed production of polyesters. The polycondensation of diethyl adipate and 1,4-butanediol using lipase CA as catalyst efficiently proceeded in l-butyl-3-methylimidazolinium tetrafluoroborate or hexafluorophosphate under reduced pressure. The polymerization of diethyl sebacate and 1,4-butanediol in l-butyl-3-methylimidazolinium hexafluorophosphate took place even at room temperature in the presence of lipase BC. ... 

The above findings are quite significant since they indicate a clear way to design solvent evaporation in the bed when the binder is a solution or the cooling time when the binder is a melt. One has to stress, however, that the above estimates are probably not very general and may require corrections for different pairs of powders and binders. Since the experimental procedure and the instrument are quite simple and straightforward to use, such measurements should be easy to perform for each specific case. 

Toxicity. The following constraint is imposed on the designed solvent to ensure low toxicity (-Log LC50) of the organic solvent. 

Viscosity of the solvent An upper limit of 1 Cp is placed on the viscosity of the designed solvent. 

In this section the performance of the designed solvent with regards to crystal morphology is verified experimentally. For verification by experiments, 2-ethoxy ethyl acetate was selected since it is an already existing solvent, and since it is one among the top 10 compounds, its properties are bound to be very similar to the properties of the optimal compound. However if we can synthesis the optimal solvent molecule, then it could also have been used in the experimental verification. 

This CAMD mixture design (solvent/anti-solvent) problem is formulated as an MINLP model as shown below. The objective function and the various property constraints in the model are discussed subsequently... 

Solvents play an important role in organic synthesis. Choice of solvent is important in improving and deciding the chemical process. Selection of solvents should be such that it has minimal effect on the environment. Today chemists are interested in designing solvents which does not pose any risk to human health and the environment. The reason why solvents are of great environmental concern is that... 

IONIC LIQUIDS DESIGNER SOLVENTS FOR GREEN CHEMISTRY... 

In conclusion, we must concur with both Shakespeare and Haldane. There are more things (a trillion more) in heaven and earth than are dreamt of in our philosophy, and, yes, the universe is not only queerer than we suppose, but queerer than we can suppose. To place the preceding observations in context, there are only about 600 molecular solvents commonly in use in industry today. So the reasons for discussing ionic liquids as designer solvents are valid with a trillion solvents to select from, an optimum solvent for any given reaction will exist. The only problem will be findiug it. Thus, we believe that the future of ionic liquids will. 

Ereemantle, M. Designer solvents—ionic liquids may boost clean technology development, Chem. Eng. News, 1998, 76(13), 32-37. 

Polarity and hydrophilicity/lipophilicity can be readily adjusted by a suitable choice of cation/anion (see earlier) and ionic liquids have been referred to as designer solvents . ... 

Because the properties (melting point, density, viscosity) and behavior of the ILs can be adjusted to suit an individual synthesis type, extraction, heat transfer, or electrochemistry problems, they can truly be described as designer solvents. 

As is seen from the presented data, ILs are true designer solvents. The modification of their constituents gives solvents with very different properties, namely, efficiency and selectivity of extraction of various solutes. In the near future, it should have important implications, as more and more finely tuned solvents are likely to appear for a variety of tasks. 

Ionic liquids are potentially Green solvents and offer interesting properties as designer solvents and can act as liquid clathrates, including neutral guest molecules. 

Index Entries Monolaurin immobilized lipase esterification experimental design solvent-free medium. 

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