Hydrophilicity Hydrophobic compounds

One particular feature of ionic liquids lies in their solvation properties, not only for hydrophobic compounds but also for hydrophilic compounds such as carbohydrates. Park and Kazlauskas reported the regioselective acylation of glucose in 99 % yield and with 93 % selectivity in [MOEMIM][BF4] (MOE = CH3OCH2CH2), values much higher than those obtained in the organic solvents commonly used for this purpose (Entry 18) [22] (Scheme 8.3-4). 

The synthesis of block copolymers by macromonotner RAFT polymeriza tion has been discussed in Section 9.5.2 and examples are provide in Table 9.9. RAFT polymerization with thioearbonylthio compounds has been used to make a wide variety of block copolymers and examples arc provided below in Tabic 9.28. The process of block formation is shown in Scheme 9.59. Of considerable interest is the ability to make hydrophilic-hydrophobic block copolymers directly with monomers such as AA, DMA, NIPAM and DMAEMA. Doubly hydrophilic blocks have also been prepared.476 638 The big advantage of RAFT polymerization is its tolerance of unprotected functionality. 

Compounds with high values are of low polarity and are described as being lipophilic and hydrophobic. Compounds with high values are of high polarity and are hydrophilic. Although the partition coefficient between octanol and water is... 

C-18 Sep Pak cartridges have become popular because of their ease of use and high efficiency for fractionating anthocyanins. In an aqueous phase, anthocyanins and other hydrophobic compounds are bound while more hydrophilic compounds such as acids and sugars can be washed away with water. The water can be slightly acidified with 0.01% HCl to stabilize the anthocyanins on the C18 resin. ... 

Hydrophilic ends, of surfactants, 22 725 Hydrophilic libers, 9 158 11 168 Hydrophilic flavor compounds, 11 551 Hydrophilic fumed silica, 22 368 Hydrophilic head group, 24 137 Hydrophilic-hydrophobic block copolymers, 20 485... 

Before using the ILs, it must be remembered that they can be dramatically altered by the presence of impurities. Impurities can change the nature of these compounds. The main contaminants are halide anions and organic bases, arising from unreacted starting material and water. The influence of water and chloride anion on the viscosity and density of ILs has already been extensively discussed by many authors [56]. The hydrophilic/hydrophobic behavior is important for the solvation properties of ILs as it is necessary to dissolve reactants, but it is also relevant for the separation and extraction processes and in electrochemical processes. Furthermore, the water content of ILs can affect the rates and selectivity of reaction (this problem was not discussed in this chapter) and can be taken as a cosolvent in extraction... 

It was shown that high molar mass lignosulfonate compounds can be fractionated by RPC into hydrophilic and hydrophobic compounds. It can be seen from Figures 4 and 5 that the birch lignosulfonates with low molar mass (fractions B and C in Figure 1) were also fractionated into hydrophilic and hydrophobic portions with no clearly resolved peaks. 

The figure shows that hydrophilic lignin derivatives (fraction I) elute in the retention time range 30-80 minutes, compared with 90-140 minutes for the hydrophobic compounds (fractions II-IV). Refractionation by analytical GPC of fractions I-IV (Fig. 9) shows that these fractions encompass wide molar mass ranges. 

The solute may itself be amphiphilic like a surface-active lipid (emulsifier) or just a simple hydrophilic or hydrophobic compound. 

Liquid-liquid extractions involve the separation of analytes from interferences by partitioning the sample between two immiscible solvents. In most cases, one of the liquids is an aqueous solvent and the other is an organic solvent. The selectivity and efficiency of the extraction process are governed by the choice of the solvent pair. In aqueous and organic solvent pairs, the more hydrophilic compounds prefer the aqueous phase and the more hydrophobic compounds will be found in the organic phase. 

---