Cosolvents for

Methacrylate monomers do not generally polymerize by a cationic mechanism. In fact, methacrylate functionaUty is often utilized as a passive pendent group for cationicaHy polymerizable monomers. Methacrylate monomers also have been used as solvents or cosolvents for cationic polymerizations (90,91). 

A partial solution to the problem of producing sharp peaks at low elution temperatures is to add a small amount of a higher-boiling co-solvent to the main solvent. As suggested by Grob and Muller (23, 24), butoxyethanol can be used as a suitable cosolvent for aqueous mixtures in such cases. 

D. F. Lowe, C. L. Oubre, and C. H. Ward, Reuse of surfactants and cosolvents for NAPL remediation, Lewis Publishers, 1999. 

Surfactants. The use of surfactants is greatly restricted in formulating ophthalmic solutions. The order of surfactant toxicity is anionic > cationic >> nonionic. Several nonionic surfactants are used in relatively low concentrations to aid in dispersing steroids in suspensions and to achieve or to improve solution clarity. Those principally used are the sorbitan ether esters of oleic acid (Polysorbate or Tween 20 and 80), polymers of oxyethylated octyl phenol (Tyloxapol), and polyoxyl 40 stearate. The lowest concentration possible is used to perform the desired function. Their effect on preservative efficacy and their possible binding by macromolecules must be taken into account, as well as their effect on ocular irritation. The use of surfactants as cosolvents for an ophthalmic solution of chloramphenicol has been described [271]. This com-... 

Use of cosolvent. Various cosolvents, such as acetone, ethanol, methanol, hexane, dichloromethane, and water, have been used for the removal of carotenoids using SC-CO2 extraction (Ollanketo and others 2001). All these cosolvents except water (only 2% of recovery) increased the carotenoid recovery. The use of vegetable oils such as hazelnut and canola oil as a cosolvent for the recovery of carotenoids from carrots and tomatoes have been reported (Sun and Temelli, 2006 Shi, 2001 Vasapollo and others 2004). For the extraction without cosolvent addition, the lycopene yield was below 10% for 2- to 5-hr extraction time, whereas in the presence of hazelnut oil, the lycopene yield increased to about 20% and 30% in 5 and 8 hr, respectively. The advantages of using vegetable oils as cosolvents are the higher extraction yield the elimination of organic solvent addition, which needs to be removed later and the enrichment of the oil with carotenoids that can be potentially used in a variety of product applications. 

Moisture. Moisture increased the extraction yield of some alkaloids as demonstrated for black tea and mat6 tea leaves (Saldana and others 1999). This can be explained considering that water can act as a cosolvent for the extraction of slightly polar compounds, whereas the presence of water is favorable at about 10-15% to increase extraction yield. 

EC was considered as an electrolyte cosolvent for the first time by Elliot in 1964, who noted that, due to the high dielectric constant and low viscosity of EC, the addition of it to electrolyte solutions would favor ion conductivity. The findings did not attract particular attention from the battery community... 

When the poor anodic stability of DMC or EMC alone on a similar cathode surface is considered, the role of EC in stabilizing the solvent system becomes obvious. A conclusion that could be extracted from these studies is that the existence of EC not only renders the electrolyte system with superior cathodic stability by forming an effective SEI on the carbonaceous anode but also acts as a key component in forming a surface layer on the cathode surface that is of high breakdown potential. It is for its unique abilities at both electrodes that EC has become an indispensable cosolvent for the electrolyte used in lithium ion cells. 

On the other hand, the presence of these esters in the electrolyte solutions raised concern over the longterm performance at room temperatures, because EIS studies indicated that the resistance associated with the SEI film increased at a much higher rate for ester-based electrolytes as compared with the compositions that were merely based on carbonates. The authors attributed this rising cell impedance to the reactivity of these esters toward the electrode active material, which resulted in the continued growth of the SEI film in the long term and suggested that alkyl esters, especially those of acetic acid, might not be appropriate cosolvents for low-temperature application electrolytes. ... 

Crystallization is often used as a method of product isolation. Crystallization of the reaction product may be induced if, to the reaction medium, in which it is well soluble, a cosolvent is added in which the product is insoluble. Because for the latter purification method the solubility should be high at high temperatures but much lower at low temperatures, the temperature coefficient of the solubility becomes an important criterion for the employment of a solvent. A further guide is the fact that substances tend to dissolve in solvents with similar polarities, so that a solvent and cosolvent for the recrystallization of a given product can be selected according to the polarities. 

Ethanol, cosolvent for supercritical fluid extraction of cholesterol from beef tallow, 125,126/... 

The second approach that has been rather popular with mixed aqueous solvents is to assume that the mixture is more or less structured than that of pure water. There is much evidence to show that the particular hydrogen-bonded structure of water influences many of the properties of electrolytes in water (15). If nonelectrolytes can modify the structure of water (15), they can have an indirect effect on the properties of electrolytes. This explanation has been particularly successful in the case of U + W mixtures (1,2). Such a simple approach is not as successful with hydrophobic cosolvents. For example, AHe°(W — W + TBA) are positive for both alkali halides (16) and tetraalkylammonium bro-... 

Equation (3.46a) indicates that the solubility of the solute in a mixed solvent system increases as the volume fraction of the cosolvent increases. Figure 3.6 shows the solubilization of hydrocortisone butyrate in a water/propylene glycol system. From the plot of Equation (3.46a), In x2m vs. solubilizing power, o, of the cosolvent for the solute. The solubilizing power is related to the partition coefficient of the solute in a water/octanol system, Kwo, as follows ... 

The total solubility of weak acid in a water/cosolvent system [HA] ot can be determined by the solubility of the un-ionized species in water, the solubilizing powers, the hydrogen ion concentration, and the dissociation constant of the weak acid. Equation (3.49d) illustrates that the total solubility of the weak acid will increase exponentially with respect to the volume fraction of the cosolvent. Even though the solubilizing power of the cosolvent for the un-ionized species is usually larger than that of the ionized species, the solubilization of the ionized species is very important in determining the total solubility when pH - pKa > oIIA - oa. ... 

Having served their purpose as masked carbonyl functionalities in the preceding 4 steps of the synthesis, the benzylidene groups in fused terpyridyl 11 are cleaved by ozonolysis in Protocol 7. As shown in Scheme 6.10, the reaction solvent is a mixture of methanol and dichloromethane. Reactant 11 is insoluble in methanol, so dichloromethane is used as a cosolvent to enhance its concentration in the cold (-78°C) reaction mixture. Methanol is a convenient cosolvent for conducting ozonolysis reactions safely because it cleaves ozonides in situ to carbonyl compounds and peroxyhemiacetals or... 

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