Ionic liquids -2-octanol

Aqueous solutions are not suitable solvents for esterifications and transesterifications, and these reactions are carried out in organic solvents of low polarity [9-12]. However, enzymes are surrounded by a hydration shell or bound water that is required for the retention of structure and catalytic activity [13]. Polar hydrophilic solvents such as DMF, DMSO, acetone, and alcohols (log P<0, where P is the partition coefficient between octanol and water) are incompatible and lead to rapid denaturation. Common solvents for esterifications and transesterifications include alkanes (hexane/log P=3.5), aromatics (toluene/2.5, benzene/2), haloalkanes (CHCI3/2, CH2CI2/I.4), and ethers (diisopropyl ether/1.9, terf-butylmethyl ether/ 0.94, diethyl ether/0.85). Exceptionally stable enzymes such as Candida antarctica lipase B (CAL-B) have been used in more polar solvents (tetrahydrofuran/0.49, acetonitrile/—0.33). Room-temperature ionic liquids [14—17] and supercritical fluids [18] are also good media for a wide range of biotransformations. 

Figure 1.6 Solid-liquid equilibria diagrams for different ionic liquids (1) in 1-octanol are [C4CjIm]Cl ( ) and [CjoCjIm]Cl ( ). (Adapted from Domariska, U. and Bogel-Lukasik, E., Fluid Phase Equilib., 218, 123, 2004 Domariska, U. and Bogel-Lukasik, E., Ind. Eng. Chem. Res., 42,6986,2003.)...

Ropel, L. et al., Octanol-water partition coefficients of imidazolium-based ionic liquids. Green. Chem., 7, 83, 2005. 

Choua, Ch-H. et al., 1-Octanol/water partition coefficient of ionic liquids, 15th Symposium of Thermophysical Properties, Boulder, CO, USA, June, 22-27, 2003. 

It is clear that the water activity is of crucial importance for the equilibrium yield in a reversed hydrolysis reaction. As expected, the equilibrium yield increases with decreasing water activity. This has been shown, for example, for the condensation of glucose and octanol [62], esterification of lysophospholipids with fatty acids [29, 63], and in normal lipase-catalyzed esterification reactions [64, 65]. The same situation is observed in ionic liquids [66]. 

The ionic liquids as the green solvents for the 0-acylation of 2-octanol with succinic anhydride brought good results for the reactions [122], Water-tolerant ionic liquid [BMlM][PFg] as the clean reaction medium was appUed to the acylation of... 

Auge and Sizun showed that octanol can be glycosylated in ionic liquids and in the presence of Sc(OTf)3 as catalyst. In the case of o-xylose, the yield of glycoconjugation is good without the necessity to use ionic liquids (Scheme 2, Table 3) [26]. 

Esterification reactions readily occur in ionic liquids. A simple example is the reaction of acetic, decanoic and octadecanoic acid with alcohols such as methanol, 1-butanol or 1-octanol. Here, Tang et al. used the ionic liquid [H-MIM][BF4] (this is a simple mixture of 1-methylimidazole and tetrafluoroboric acid) as a solvent and catalyst for the reaction [189]. Singer and coworkers have shown that benzoyl chloride reacts with ethers to give alkyl benzoates [190] in chloroaluminate(iii) ionic liquids. This reaction results in the acylative cleavage of ethers, and a number of reactions with cyclic and acyclic ethers were investigated in the ionic liquid [EMIMjl-AICI3 (X = 0.67). Two examples are shown in Scheme 5.2-79. 

Thus it has been demonstrated that typically hard anions such as NOj", Cl", and 804 associated with Sr complexed by crown ethers are only partly, if at all, extracted from 1-octanol into l-methyl-3-pentylimidazolium bis[(trifluoromethyl)-sulfonyljamide ionic liquid [17]. As a consequence, ligands containing a -SOjNa hard moiety or similar hard anions could be not really soluble in a soft ionic liquid and could form a secondary phase (microdomains). 

Figure 21.7 Novel ionic liquids for CC column coating, (a) l-Benzyl-3-methylimidazolium trifluoromethanesulfonate [BzMIM][OTf]. (b) l-(4-Methoxyphenyl)-3-methylimidazolium trifluoromethanesulfonate [MeO-PhMIM][OTf], (c) Separation of polar/nonpolar mixture CHjClj (1), methyl caproate (2), octyl aldehyde (3), dodecane (4), octanol (5), tridecane (5), naphthalene (7), nitrobenzene (8), tetradecane (9), pentadecane (10), and octanoic acid (11). Conditions 80°C for 3min, 10°Cmin" to...

Electrochemistry at liquid/liquid interfaces has progressed markedly in the past 30 years. Excellent work on modified liquid/liquid interface with lipids and nanoparticles have been reported (75, 78, 124-127). Droplet electrodes and three-phase jnnctions have made this field more popular and versatile (102, 103, 128). The ET induced IT reactions at three-phase junction have been employed to obtain the log P of different drugs at W/n-octanol interfaces (102, 129, 130). New and less toxic solvents, such as room tanperature ionic liquids (RTILs) have replaced organic solvents to form W/RTIL interfaces (131, 132). However, from a theoretical point of view, the key aspects of potential distribution remain the major challenge. Only a few biological applications have been so far reported based on the techniques developed from this field. 

Lipophilicity of a molecule is measured by its distribution behavior in a biphasic system either liquid-liquid (partition coefficient in 1-octanol-water) or solid-liquid (retention in RP-TLC or RP-HPLC) systems. According to definition suggested by lUPAC lipophilicity expresses the affinity of a molecule for a lipophilic environment. A reference scale representing lipophilicity appears to be the solute distribution between octanol and water. Berthod Carda-Broch (Berthod Carda-Broch) proposed another lipophilicity scale measuring ionic liquid BMIM PFg-water distribution constants. Relationship between the obtained values and respective octanol-water coefficients for a series of aromatic compounds differing in acid-base properties revealed that only the neutral compounds or ionizable ones with zwitterionic properties showed similar distribution behavior in the... 

Fig. 1. Ionic liquid/water distribution coefficients compared to the octanol/water values (log scale). Crosses amino-aromatic compoimds, open triangles neutral compounds or compounds with both acidic and basic substituents, filled-diamond acidic and/or phenolic compounds ( http //www.mariecurie.org/annals/volumeS/berthod.pdf).

Table 16.2.2. Compilation of octanol-water partition coefficients (Kqw) for ionic liquids.

Chapeaux A, Simini LD, Stadtherr MA, Breimecke J (2007) Liquid phase behavior of ionic liquids with water and 1-octanol and modeling of 1-octanolwater partition coeflicients. J Chem Eng Data 52 2462—2467... 

Lee SH, Lee SB (2009) Octanol/water partition coefficients of ionic liquids. J Chem Technol Biotechnol 84 202-207... 

Lee B-S, Lin S-T (2014) A priori prediction of the octanol-water partition coefficient (KOW) of ionic liquids. Fluid Phase Equilib 363 233-238... 

Journal of Organic Chemistry, 62,3,669-672, ISSN 0022-3263 Bender, J., Jepkens, D. Hiisken, H. (2010). Ionic liquids as phase-transfer catalysts Etherification reaction of 1-Octanol with 1-Chlorobutane. Organic Process Research Development, 14,3, 716-721, ISSN 1083-6160... 

Figure 9 shows that tryptophan can be solubilized with the addition of AOT, octanol, and water. At lower pressures, the surfactant partitions mostly into the liquid phase, and tryptophan is only sparingly soluble. At pressures above 140 bar, the liquid phase disappears as the AOT, octanol, and water form micelles in the fluid phase. The micelles cause the solubility of tryptophan to increase dramatically. The solubility becomes well above 0.1 wt.%, which is quite sufficient for practical applications. At pressures above 200 bar in the solid-fluid region, solubilities vary little with pressure, which is consistent with the relatively constant polarities shown in Figure 7 for similar values of Wq. This ability to adjust solubilities of ionic species at modest temperatures and pressures opens up the possibility of interesting new practical applications. 

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