Decane, solubilization

Figure 1 shows the spectrum obtained for n-perdeutero decane solubilized in the lamellar phase of water and C E. a comparison with the spectrum of n-perdeutero hexadecane (Fig. la) from the preliminary investigations by Ward at al (3) is instructive. In both cases, the spectrum may be simulated by a number of overlapping spectra corresponding to half the number of carbon atoms in the solubilized chain. 

Figure 12.11 Decane solubilization limit in CisSE/cosurfactant/water systems. W, is the weight fraction of cosurfactant in the CisSE + cosurfactant mixture. Filled symbols ...

The insufficient disordering is illustrated by the fact that the decane solubilization is limited and by the solubility gap along the sodium dodecyl sulfate (SDS)/W-C50H axis. The latter is caused by the lamellar liquid crystal between the aqueous and pentanol solution (Figure 1.8). 

Figure 3 shows the solubilization of triolein in Newcol surfactants. Figure 4 shows the solubilization of n-decane in the same surfactant solutions. The general characteristics of the curves in Figures 3 and 4 are the same as those shown in Figure 2. 

From the lower turbidity values shown in Figures 3 and 4, one may estimate that the solubilization of oleic acid is higher than triolein or n-decane in Newcol surfactant solutions. It is difficult to make further distinction between triolein and n-decane from Figures 3 and 4. 

The phase diagram of some oil-solubilizer-water must be measured as a function of temperature in order to test the above approach. For this purpose decane (DEC) was chosen as a typical oil and 2-bu-toxyethanol (BE) as the solubilizer. We thought BE would be a good model solubilizer since the lower critical solution temperature for the BE-H2O system is 49 C this gives a good workable temperature range for our investigation. 

Two main microemulsion microstructures have been identified droplet and biconti-nuous microemulsions (54-58). In the droplet type, the microemulsion phase consists of solubilized micelles reverse micelles for w/o systems and normal micelles for the o/w counterparts. In w/o microemulsions, spherical water drops are coated by a monomolecular film of surfactant, while in w/o microemulsions, the dispersed phase is oil. In contrast, bicontinuous microemulsions occur as a continuous network of aqueous domains enmeshed in a continuous network of oil, with the surfactant molecules occupying the oil/water boundaries. Microemulsion-based materials synthesis relies on the availability of surfactant/oil/aqueous phase formulations that give stable microemulsions (54-58). As can be seen from Table 2.2.1, a variety of surfactants have been used, as further detailed in Table 2.2.2 (16). Also, various oils have been utilized, including straight-chain alkanes (e.g., n-decane, /(-hexane),... 

Caution should be exercised in evaporation of the ether, as the di tert-butoxy compounds are appreciably volatile at reduced pressure. If a rotary evaporator is used for the concentration, the water bath should be kept at or below room temperature, and the residue should not be pumped after it is clear that the bulk of the ether has been evaporated. The submitters report ca. 130 g of oily residue at this stage. Treatment of the oily residue with 105 mL of ether leads to partial crystallization. During washing of the crystals in a Buchner filter with more ether, an almost complete solubilization takes place, but eventually 0.1-0.5 g of cis-2,3,7,10-tetraoxabicyclo[4.4.0]decane remains as an insoluble residue. This compound... 

We have developed new reaction systems based on colloidal dispersions [23, 24], namely highly concentrated water-in-oil (gel) emulsions, which could overcome most of the disadvantages of the aqueoussolvent mixtures such as inactivation of the aldolase and incomplete aldehyde solubilization in the medium. These emulsions are characterized by volume fractions of dispersed phase higher than 0.73 [25] therefore, the droplets are deformed and/or polydisperse, separated by a thin film of continuous phase. Water-in-oil gel emulsions of water/Ci4E4/oil 90/4/6 wt%, where C14E4 is a technical grade poly(oxyethylene) tetradecyl ether surfactant, with an average of four moles of ethylene oxide per surfactant molecule and oil can be octane, decane, dodecane, tetradecane, hexadecane, or squalane, were typically chosen as reaction media [23, 26]. 

One of the most Illustrative example possible Is the change In water solubility when polyethyleneoxlde was added to a W/0 mlcroemulslon stabilized by a polyethyleneglycol alkyl ether surfactant (16). The maximum water solubilized by adding tetraethyleneglycol dodecyl ether to decane could be approximated by the equation... 

Again, an examination of water solubilization into micelles in various solvents helps explain the differences for this surfactant and AOT. The uptake of water into 0.1 M Cn-14 EO5 was found to increase as ACN decreased from 10 (decane) to 5 (pentane). We do not expect that this increase would continue all the way to ethane. However, we do find that the optimal ACN for water uptake into this surfactant is less than 8, the value for AOT. The lower ACN for Ci 1-14 EO5 versus AOT could be a factor in the explanation of their different behavior in ethane. 

For solutions of typical ionic surfactants with no added salts the studies of Carroll and Ward showed that solubihzation rates were much smaller than those for nonionic surfactants, presumably because the surfactant ions adsorbed at the oil-water interface repelled the micelles of like charge in the solution. Indeed, Bolsman et al. found no measurable solubilization of n-hexadecane into solutions of a pure benzene sulfonate and a commercial xylene sulfonate. They injected small oil drops into the surfactant solutions and observed whether the resulting turbidity disappeared over time due to solubilization. Similarly, Kabalnov found from Ostwald ripening experiments that the rate of solubilization of undecane into solutions of pure SDS was independent of surfactant concentration and about the same as the rate in the absence of surfactant. That is, the hydrocarbon presumably left the bulk oil phase in this system by dissolving in virtually miceUe-free water near the interface. In similar experiments TayloC and Soma and Papadopoulos observed a small increase in the solubilization rate of decane with increasing SDS concentration. De Smet et al., who used sodium dodecyl benzene sulfonate, which does not hydrolyze, found, like Kabalnov, a minimal effect of surfactant concentration. 

More recently, Pena and Miller investigated solubilzation rates of mixtures of n-decane and squalane into 2.5 wt% solutions of pure C,2Eg at 23°C using the oil drop method described above. They first measured the rate of solubilization of pure decane, confirming that the rate was controlled by interfacial phenomena as in Carroll s work, and demonstrated that pure squalane was not solubilized to any significant extent under these conditions. Next they measured solubilization rates of decane from various mixtures of the two hydrocarbons. Figure 9.7 shows results from one of these experiments together with predictions of a model based on assuming that the rate of decane... 

As shown in Figure 3.9, the L2 phase is able to solubilize a very large amount of a hydrocarbon such as decane or hexadecane. In fact, a composition containing up to 75% decane and water/surfactant/cosurfactant proportions corresponding to the L2 phase is still clear, fluid and isotropic, forms spontaneously, and is thermodynamically stable. The structure of this microemulsion can be (to some extent) regarded as a dispersion of tiny water droplets (reverse micelles) in a continuous phase of the hydrocarbon. The surfactant and cosurfactant are mainly located at the water/oil interface. This type of system is often referred to as a w/o microemulsion. 

It was stated earlier that the solubility of decane in the LI phase is almost zero. For a well-defined surfactant-to-cosurfactant ratio, very large quantities of decane (or any hydrocarbon) can be solubilized in the LI phase. A thin, snake-like singlephase domain develops toward the oil vertex of the phase diagram (Figure 3.10). This phase can be regarded as amphiphile micelles swollen with oil. 

Beilstein Handbook Reference) Amidex CP N.N-Bis(2-hydroxyethyl)decan-1-amide BRN 1785093 Capramide DEA Capric acid diethanolamide Deoanamide, N,N-bis(2-hydroxy-ethyl)- EINECS 205-234-9 Standamid CD Upamide CD, Capramide DEA (2 1) - diethanolamine detergent, foam enhancer for anionic systems solubilizes fragrances into hydroalcoholic systems ... 

Swelling effect. Oil molecules are solubilized in the aggregate s core and expand its volume. In this case, as is almost constant. Since the volume of the surfactant s hydrophobic tail is increased, the surfactant mean curvature tends to be more positive (i.e., more convex toward water) in order to maintain Us constant. Thus, for the hydrophilic Ci2(EO)7 (whose curvature tends to be positive), the swelling effect will be dominant, leading to the Hi-Ii transition. However, when an aromatic oil like w-xylene is used instead of decane, it penetrates into the surfactant palisade layer and makes the curvature negative, leading to the Hi-L, transition [296]. 

Water solubilization in AOT reverse micelles has been studied by measurements of Wq at the phase boundary, Wq at a fixed temperature [16,20,21,48]. The data are in reasonable agreement for the heavy solvents octane, nonane, and decane and for the light solvents ethane, propane, and butane, but the results are not in agreement for the intermediate solvents pentane, hexane, and heptane [20]. To determine the location of for these solvents, phase boundary plots of the type shown in Fig. 3 were constructed, and a constant-temperature line was drawn across the plot to determine This is a much more reliable technique than the alternative procedure of adding water aliquots to a reverse micelle solution at a fixed temperature, because the phase boundary can be difficult to observe in such an experiment [19]. 

Water-in-oil (W/O) microemulsions have been investigated for topically applied products using hexadecane or decane as oil with a surfactant blend of glycerol monooleate and laureth-23, with and isopropanol as a cosurfactant [7]. Up to 29% water could be solubilized in a system of 35% decane, 21% glycerol monooleate/laureth-23 (5 1), and 14% isopropanol. With hexadecane, 25% water was solubilized using 25% glycerol monooleate/laureth-23 (2 1) and 12% isopropanol. 

The investigators focused on solubilizing insulin in GMO/decane/water, GMO/ decane/glycerol/water, and GMO/phosphatidylchoUne (PC)/decane/glycerol/water... 

Aside from the coil-coil diblocks and coil-coil-coil ABA triblocks, crystalline-coU poly(ferrocenyldimethylsilane)-foZock-poly(dimethyl silox-ane) or PFS-PDMS diblock copolymers were reported by Raez, Manners, and Winnik [42] to form nanotubes readily in block-selective solvents hexane and n-decane, which solubilized the rubbery PDMS blocks and not the crystalline PFS blocks. 

Unlike the experiments carried out below the cloud point temperature, appreciable solubilization of oil was observed in the time-frame of the study, as indicated by upward movement of the oil-microemulsion interface. Similar phenomena were observed with both tetradecane and hexadecane as the oil phases. When the temperature of the system was raised to just below the phase-inversion temperatures of the hydrocarbons with C12E5 (45°C for tetradecane and 50°C for hexadecane), two intermediate phases formed when the initial dispersion of Li drops in the water contacted the oil. One of these was the lamellar liquid crystalline phase L (probably containing some dispersed water). Above this was a middle-phase microemulsion. In contrast to the studies carried out below the cloud point temperature, there was appreciable solubilization of hydrocarbon into the two intermediate phases. A similar progression of phases was found at 35 C when using / -decane as the hydrocarbon. At this temperature, which is near the phase-inversion temperature of the water-C12E5-decane system, the... 

Figure 19.19. Relative viscosity as a function of micelle volume fraction for solutions of spherical micelles. The dashed and continuous curves give theoretical predictions for two models of spherical particles, in the latter case taking into account particle-particle interactions. The system exemplified is that of C12E5 micelles with equal weights of solubilized decane. (Redrawn from M. S. Leaver and U. Olsson, Langmuiry 10 (1994) 3449)...

Rabie et al [ 122] reported similar results with heptanol, a relatively long-chain alcohol in the system AOT/decane/water and showed that by using the titration method (see Section 3.3), the value of w (around 45 in absence of heptanol) increased to about 90 with a heptanol/AOT molar ratio of about 0.35. As expected, the w value decreased drastically with further addition of heptanol. It was concluded that when in excess, the alcohol acts as a co-solvent rather than a co-surfactant. The observation of Caillet et al. [ 126] that the water solubilization capacity of different alcohols ([ 1 -alkanol]/[AOT] = 0.5, temperature 25"C) reaches a peak in the system AOT/n-decane/ water with increase of the chain length up to C7 has been already mentioned. As for benzene, not a usual co-surfactant, Rabie et al. [122] confirmed a rise of w from about 45 to a peak of 75 at a benzene/AOT molar ratio close to 10. 

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