Solvent, importance

A. Loupy, A. Zaparucha, Asymmetric Michael Reaction under PTC Conditions without Solvent. Importance of re Interactions for the Enantioselectivity , Tetrahedron Lett. 1993, 34, 473-476. 

PAMAM dendrimers are large (G4 is 4.5 nm in diameter) and have a hydrophilic interior and exterior accordingly, they are soluble in many convenient solvents (water, alcohols, and some polar organic solvents). Importantly, the interior void spaces are large enough to accommodate nanoscopic guests, such as metal clusters, and are sufficiently monodispersed in size so as to ensure fairly uniform particle size and shape. As we will show later, the space between the ter-... 

Solvents are substances that are liquid during application and will dissolve other substances, which can be recovered unchanged on removal of the solvent. Importantly, the solvents and the solutions involving them must be applicable for some purpose. Solvent systems must be understood before any rationale chemical process can be developed. 

In the first report about immobilization of peroxidases on mesoporous materials, Takahashi and coworkers shed light on different parameters that affect the process. Using horseradish peroxidase (HRP) as a model, the authors reported that higher stability to temperature and organic solvent, important variables on industrial processes, were obtained when the size of the pore match the size of the enzyme, in such a way that the encapsulated enzyme was located in a restricted space that slowed down its free movement, preventing its denaturation [4],... 

Organoaluminium compounds are stronger Lewis acids than organomagnesium compounds and form complexes with basic solvents. In ethers, for instance, R3AI either does not react at all with oxiranes or gives a very low yield of product and, accordingly, hydrocarbons are preferred as solvents. Important roles are played in the reaction by the molar ratio of R3AI to oxirane and the nature of the R substituents. 

A number of properties, including dielectric properties, should be considered in assessing a given polar solvent. Important bulk properties are density, vapor pressure, thermodynamic properties related to vaporization, heat capacity, viscosity, compressibility, and surface tension. Some of these are summarized in table 4.1 and are discussed briefly in this section. 

Analogous additions were later reported by Ito and co-workers (Scheme 9) (20). The enamines for these additions were prepared from the corresponding aminals using a mild base in the presence of trimethylsilyl chloride. In turn, the aminals used are available from (— )-ephedrine and (S)-prolinol. The byproduct amine hydrochloride was removed either by distillation or by precipitation from a benzene solution. Enamines prepared by this method were found to be unreactive toward unsaturated carbonyl compounds in a variety of solvents. Importantly, it was found that use of a mild Lewis acid such as anhydrous MgCl2 or ZnCl2 in THF promoted the reactions. Thus, the addition of enamines 9.1 and 9.2 to methyl acrylate is achieved. Of the two enamines, the proline-derived 9.1 is the more effective auxiliary. The... 

Solvated metal cations have exclusively been studied and frequently the solvent is water. In many cases the number of water or other solvent molecules coordinated to the cation is known. Why is solvent exchange of a solvent molecule between a coordinated solvent molecule and one of the bulk solvent important to investigate In principle, any solvated metal cation is of interest since the chemical reactivity of a solvated ion in solution is intimately coimected with its stability and lability of the coordinated solvent molecules. Thus, knowledge of the solvent exchange characteristics is of fundamental importance in... 

Successful development of a commercial-scale solvent-extraction process depends to a large degree on selection of the most appropriate solvent. Important criteria for solvent selection include price, toxicological constraints, availability, solute selectivity, recovery difficulties, physical properties (water solubility, specific gravity, viscosity, boiling point), and operational hazards (flammability, volatility). Final choice would likely be a compromise among these criteria. 

This diversity of solvent-dependent heme cooling rate and mechanism in Mb and Cyt c is a direct result of the difference in heme local environment in the two proteins. In Cyt c, all three direct energy transfer pathways between the heme and solvent, important in Mb, are missing or substantially less effective. The two isopropionate side chains of heme in Cyt c are onbedded in the protein and energy... 

Important general characteristics of mobile-phase solvents important in TLC include ... 

Kim, D.S., Nepal, D. Geckeler, K.E. (2005). Individualization of single walled carbon nanotubes is the solvent important Small, 1,1117-1124. 

Lipids Lipids are chemical components of the cell that are insoluble in water but soluble in nonpolar solvents. Important lipids include fatty acids, triglycerides, phospholipids, glycolipids, and steroids. Lipids Lipids compose many of the structural components of cells. Lipids are also used for long-term energy storage and for insulation. In the diet, saturated fats— triglycerides containing no double bonds in their carbon chains—are more likely to increase the risk of stroke and heart attack than unsaturated fats. 

As this chapter indicates water is not simply a cheap and environmentally benign solvent, important though that is. Instead, the hydrophobic effect seen in water permits chemistry otherwise not accessible. It permits the construction of enzyme mimics that use hydrophobic forces to bind the substrates to the catalysts. It permits those reactions, and others, to achieve... 

It should be noted that unlike in the EU, the US EPA uses photochemical reactivity of organic compounds as a criterion to identify an organic solvent as a VOC. The US EPA has released a list of exempt solvents that have negligible photochemical reactivity. Methyl acetate, acetone, tert-butyl acetate, dimethyl carbonate and propylene carbonate are some examples of exempt solvents important for the coating industry. Per the US EPA, VOC concentration is calculated according to the following formula and expressed as mass per unit volume ... 

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