Water 1-hexanol, 210 Table

The values obtained for n-hexanol-water were = 24.6 and = 1.9 dynes/cm and for water-hexanol, = 22 and yf = 12.4 dynes/cm. As regards the contact angle results obtained with n-hexanol, values of Oow obtained from Equations 14 and 15 and by experiment show a wide disparity. See Tables IV-VII. For paraffin wax, both equations predict zero contact angle for n-hexanol whereas the experimental values are 45° 6a) and 37°C Or), As discussed earlier, adsorption of alcohols at the solid/liquid interface may affect the wetting behavior of substrates. These effects are not accounted for by the Fowkes or Wu treatment, and hence it is not unexpected that these equations do not correlate with experimental Oow values for hexanol/water. 

The cryofracture measurements showed individual spherical forms for the Triton X-lOO-decanol-water microemulsion, whereas the spherical forms were tightly packed together for the CTAB-hexanol-water microemulsion (Table 3) [20]. 

As seen in Scheme 8.55, alcohols react,reversibly, with carboxylic acids to produce esters and water. As will be discussed later (Chapter 10), but should be clear from the scheme, the hydrolysis (reaction with water) of esters produces carboxylic acids and alcohols. In a similar vein, if an ester (such as methyl ethanoate [methyl acetate, CH3CO2CH3],Table 8.6, item 17) is treated with an excess of alcohol (such as cyclo-hexanol,Table 8.6, item 17) in the presence of an acid catalyst and (generally) heated at a temperature above the distillation temperature of the alcohol with which the acid is esterilied, ester interchange can be effected (Scheme 8.58) through the addition of the higher boiling alcohol to the carbon of the carbonyl followed by expulsion of the lower boiling one. 

When considering bipolar solutes (e.g., aniline, 1-hexanol, phenol, hexanoic acid), we can see that depending on the relative magnitudes of the solvent s at and /3, values, solute solvent interactions may become quite attractive. For example, for aniline, for which j6 trichloromethane is still the most favorable solvent, whereas for phenol (a, > j6,), diethylether wins over the others. Finally, due to the lack of polar interactions in hexane, bipolar solutes partition rather poorly from water into such apolar solvents (Table 7.1). 

Turning now to the solid/water/oil measurements, we compare the predicted Ooic values according to Equations 14 and 15 with experimental values in Tables IV-VII for the substrates investigated. In the case of Teflon, where it is possible to test Equation 11, values are given for heptane and n-hexanol. The dispersion and polar components of the surface tension of water-n-hexanol, i.e. water saturated with n-hexanol, and hexanol-water were obtained by measuring the contact angle of liquid drops on paraflSn wax (ys = 25.5 dynes/cm), which served as a... 

Table I shows the effect of various systems such as micelles, swollen micelles (achieved by adding hexanol to CTAB), microemulsion systems, vesicles formed from a double-chain CTAB surfactant, and reversed micelles with water cores formed with benzyl dimethylcetylammonium bromide in benzene. Hie active chromophore exists either as pyrene, pyrene sulfonic acid or pyrene tetrasulfonlc acid. Essentially the concept here is that the polar derivatives of pyrene will always locate pyrene at the surface of the micelle as these anionic species of pyrene complex with the positively charged surface. Dimethylaniline is used as an electron donor in each case, it can be seen that for pyrene, a continual decrease in the yield of the pyrene anion (ion yield of unity in the micelle) is observed on going from micelle to swollen micelle, to microemulsion, and no yield of ions is observed in a reversed micelle system. With pyrene tetrasulfonic acid the yield of ions over the different systems is fairly constant, even across to the reverse micellar system. However, the lifetime of the ions is extremely short in the reversed micellar system. An explanation for such behavior can be given as follows as we transverse across the...

Salter (l8 divides the alcohols into three main groups on the basis of their oil/water solubility. Isopropyl alcohol is of the water soluble group, isobutyl alcohol is of the intermediate group, and 2-hexanol is of the oil soluble group. Table IV gives some results for alcohols of each class. No strong effect was seen. We have previously reported (15,) on the ability of alcohols to reduce the viscosity of sodium oleate gels. 

The fluorescence decay rate constants, k , of several fluorescent probes in various systems (Table I) provide further evidence for hydrophobic microdomains in PA-I8K2 aqueous solutions. All the decays are single exponential decays except for C PN in aqueous solutions of PMA at pH 8. All the values in PA-I8K2 aqueous solutions at pH 4, 8, and 10 are similar to those found in hexanol and much smaller than those in water and aqueous solutions of PMA at pH 8. In summary, PA-I8K2 readily solubilizes pyrene and some positively and negatively charged derivatives of pyrene, especially long-chain derivatives. 

Behl et al. studied the effect of prolonged contact of hairless mouse skin with water on permeability coefficients. The authors showed that permeability coefficients increase after extended periods of hydration. Because other permeability coefficients in the database we have assembled were measured on previously unhydrated skins or skins that were hydrated for short periods, the permeability coefficients with the shortest hydration time (0.3 to 0.8 h) from Table 1 were selected for the validated database. Permeability coefficients were determined with either water or ethanol as a copenetrant. The concentrations were dilute (alcohol concentrations less than 10 M) and probably were not damaging. Six reported measurements were averaged for methanol, two for ethanol, and two for butanol, and permeability coefficients were reported singly for hexanol, heptanol, and octanol. Although this article did not specify the diffusion cell temperature, subsequent articles by the same authors describing similar data indicated that the temperature was 37°C (e.g., Behl and Barrett, 1981 Behl, El-Sayed, et al., 1983 Behl, Linn, et al., 1983). It seems hkely that the temperature was also 37°C in the experiments described in this article. 

Table 6 Correlation Times Microemulsions Tj. (s) for Spin Probes I and II in CTAB- 1-Hexanol-Water ...

Tables Electron-Nitrogen Hyperfine Coupling Constants for Spin Probes I and II Dissolved in CTAB-Hexanol-Water Microemulsion...

Finally, the nitrogen hyperfine coupling (4, in gauss) is highly dependent on the medium polarity. The A values can therefore be used to characterize the local polarity in the microemulsions [66,68]. The A values of spin probes I and II (Table 8) show clearly that they are close to the hexanol value and are quite different from that obtained in water. The interface can therefore be assumed to be nonpolar, and no water penetration can be detected in our system. Note that even the nitroxyl group of spin probe II, although close to the polar headgroup, is not in direct interaction with the more polar interface. 

Table 11 Kinetic Data Obtained int the CTAB 18 /o-Hexanol 70%-Water 12% Microemulsion at 25 C, pH 6.5, and [Mu ] = 2.5 x lO w...

The results obtained in the CTAB-hexanol-water microemulsion are reported in Table 11. The second-order rate constants are not dependent on either the nature or the concentration of the metal ions. It can thus be accepted that these values, 9.4 ( 0.2) X 10- dmV(mol s), represent the rate of rearrangement of the microemulsion droplets. These values are not very dependent on the R values. Only some 10% increase is observed from R = 6 to / = 24. 

Table 12a Composition and Size of Microemulsion Aggregates in the CTAB-Hexanol-Water Microemulsion Containing NiCb...

Yields for several alcohols were determined for the reaction of particle board at 190°C for 40 min reaction time (2% sulfuric acid catalyst). The results for the various alcohols are given in Table II. Methanol and ethanol are essentially equivalent in forming the alkyl levulinate on a weight percent basis. For longer-chain alcohols, the yields drop off substantially with size. In the case of the aminoethanol, methoxyethanol, and hexanol, the solid material is recovered as brown granules and cannot be dried easily. No alkyl levulinate is found in the solvent phase. By comparison with water as the solvent, the charcoal yield was 46 wt% and the levulinic acid was 18% as determined by gas chromatography. 

Table 1 shows the effect of the addition of isobutanol on various properties of oil/brine/surfactant systems for TRS 10-410 and TRS 10-80. Because the same IFT values were obtained for the systems with and without IBA (Table 1), the observed differences in oil recovery cannot be explained in terms of any change in IFT. The presence of alcohol did not significantly influence the partition coefficient of surfactant in n-dodecane or n-octane. It is important to emphasize that the partition coefficient changes sharply near the ultralow IFT region (19). Thus, the partition coefficient does not appear to correlate with the oil displacement efficiency. However, the presence of isobutanol decreases the interfacial viscosity and markedly influences the flattening time of the oil droplets. It has been suggested (18) that a rigid potassium oleate film at the oil/water interface can be liquefied by the penetration of the hexanol molecules in order to produce spherical microemulsion droplets. It has been shown (14) also that for a commercial petroleum sulfonate-crude oil system, the oil droplets with the alcohol coalesce much faster than the ones without alcohol. For the systems studied here, IBA is believed to have penetrated the petroleum sulfonate film as seen by the decrease in IFV. The decrease in interfacial viscosity would presumably promote the coalescence in porous media. 

As shown in Table 7, of the two alkanols relative to that in pure water is significantly greater in 2 M NaCl solution than in 2 M solutions of LiSCN and NaSCN, which is in accord with the effect of the respective salts on the aqueous solubility of 1-octanol (ref. 22). In 2 M NaCl solution AF of 1-octanol is more negative than that of 1-hexanol, but it is reversed, as reflected in K , in... 

Table A1-5 (Solubility) is sorted first based on the type of each solvent in alphabetical order (acids, alcohols, aromatics...spedals) and then second, based on the name of each solvent in alphabetical order within type (1-hexanol, amyl alcohol, benzyl alcohol...texanol). One uses Table A 1-5 to obtain information about solubility parameters and water solubility for and of a solvent based on its name within type.

TABLE 1 Thermal Characteristics of W/O Microemulsions in the System Water-Hexadecane-K-Oleate-Hexanol... 

FIG. 9 The effect of different thermal rates on the DSC spectra recorded upon the melting of a previously frozen sample. First-order phase transitions are rate-independent. However, the smaller the final step from the dynamic to the isothermal part of the measurement (iso.T in time units), the lower wiU be the difference between the sample and reference temperatures. Water-hexadecane sample with C = 0.25. (a)-(d), dTIdt = 1, 2, 4, and 8 K/min. Composition is given in Table 2. Symbols A//, w i,x are used to identify the thermal peaks due to the melting of hexadecane (h), water (w), K-oleate-hexanol-water mixture (b), and hexanol (x). (From Ref. 13.)... 

FIG. 15 Water-hexadecane system (Table 2). DSC-ENDO spectra of the upper isotropic phase of biphasic samples with increasing water concentration of the sample as a whole. Curve 1 Ctoi = 0.372, the first appearance of a birefiingent liquid crystalline lens. Curve 2 Ct = 0.388. Curve 3 Ct = 0.419. Curve 4 Melting endotherms of the Uquid crystalline bottom mesophase of a sample with Ct , = 0.419. AH and AHb are the thermal contributions of the n-hexanol and the water-K-oleate-hexanol mixture, respectively. (From Ref. 23.) Curve 5 DSC-ENDO spectrum of the ternary mixture n-hexanol-K-oleate-water. The proportions between surfactant and cosurfactant are the same as those used to formulate the four-component W/O microemulsions. 

TABLE 8.8 Optimized UNIQUAC binary aij for the system [water (1), ethanol (2), 2-etyl-l-hexanol (3)] at different temperatures (aij is expressed in Kelvin). 

The LLE measurements for the ternary system were made at atmospheric pressure in the temperature range at (298.2, 303.2, and 305.2 2) K. The experimental and correlated LLE data of water, 1-hexanol and TEA at each temperature are obtained. Experimental tie line data for (water + 1-heaxol + TEA) at each temperature were reported in Table 15.1. 

TABLE 15.1 Experimental tie line data for (water + 1-hexanol + TEA) at each temperature ... 

TABLE 18.1 Experimental and predicted LLE data at each temperature, together with the RMSD% values for [water (1) + acetic acid (2) + 2-ethyl-1-hexanol (3)]. 

The experimental and HYSYS-UNIQUAC LLE data for (water + acetic acid + 2-ethyl-l-hexanol) at different temperatnre of (298.2 to 313.2) K, are presented in Table 18.1. The estimated uncertainties in the mole fraction were about 0.0005. From the LLE phase diagrams (Figures 18.1-18.4), (2-ethyl-l-hexanol + water) mixture is the only pair that is partially miscible and two liquid pairs (acetic acid + water) and (acetic acid + 2-ethyl-l-hexanol) are completely miscible. The mutual solubility of 2-ethyl-l-hexanol and water is very low and therefore, the high boiling point solvent (2-ethyl-l-hexanol) can be used as a reliable organic solvent for extraction of acetic acid from dilute aqueous solutions. 

TABLE 18.4 Othmer-Tobias equation constants for (water + acetic acid + 2-etliyl-l-hexanol). 

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